Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: BDA on Wednesday,July 24, 2019, 04:05:55 PM
-
On other threads I've mentioned that I'm not satisfied with the handling of my car. This will be an ongoing (until I'm either satisfied or I give up) thread of my attempts to make it handle the way I think it should.
Mainly, my complaints have been that it feels like will go into severe oversteer going into a turn at speed, fast highway driving (>60mph) requires intense concentration partially because minute steering inputs seem to generate outsized results and also because the car feels a little twitchy.
Here's a bit of what I'm working with. It probably isn't exactly what you have but it might be close enough for you to gain from my experience or I might gain from yours.
What follows is my "starting point." I have a TCS, Richard's twin link rear suspension. Richard's upper front A-arms adjustable for camber. I have SPAX adjustable shocks. SPAX is not sure how many adjustment clicks mine have because they changed the design years ago but it is expected my shocks have 14 clicks.
Tires: Front: 195/50-15, Rear: 205/50-15
Pressure: Front: 15 - 18 psi, Rear: 24 - 26 psi (Richard's suggestion)
Springs: Front: 250#, Rear: 130# (also Richard's suggestion)
Shocks: Front: 3 clicks, Rear: 3 clicks
Alignment: (D = driver's side, P = passenger side)
Front toe: .20' degrees
Front camber: D: -3/8°, P: -1/4°
Front caster: D: +2 1/2°, P: +1 7/8°
Rear toe: .20' degrees
Rear camber: D: -1/2°, P: -1/2°
In general, the idea was to have as little rear toe-in as I felt comfortable with to hopefully give my rear tires a few more miles. I also thought that with wide tires, camber maybe should be on the bottom side of the spec.
This is not the beginning of my attempts but this seems like a good time to start. I've decided to put it on a rack to get a good baseline. Also, the shop owner, Gerry, suggested he had some insights into suspension tuning and I was interested in what he had to say. I can also compare what my alignment gear reads and what the big rack reads. To that end, I brought my car to him this morning.
The first thing Gerry told me is that my tire pressure was too low. I have to say that I was a bit surprised by the pressures Richard told me but I figured he knew a lot more about Europas and how to set them up than I. Gerry inflated the tires to 30 psi and that I might want to go to 35 psi in the rear. The next thing he thought was that my camber should be about -1° all around.
The result of Gerry's alignment was:
Front toe: .32' degrees
Front camber: D: -0.9°, P: -0.6°
Front caster: D: 2 .7°, P: 1.5°
Rear toe: .51' degrees
Rear camber: D: -1.0°, P: -0.9°
None of that is particularly noteworthy. Everything is pretty much within specs except for the passenger side front caster. I'm going to try adding a couple of washers to see if I can bring that up. I doubt it will make that much difference though. When Gerry was adjusting the camber on the driver's side front, the passenger front camber was -1.0° so that changed "on it's own". When I got home and checked on my camber gauge, I got about -0.6°. I will put in a little more negative camber on the passenger side. One thing I note is the rear toe equates to 0.20" which is within specs but on the high side (1/8" to 1/4"). I may try reducing that to aid tire wear.
So what was the result? It was a significant improvement. It's not near to where I want it but it is definitely in the correct direction. Going into a turn, the backend still feels loose but the overall stability is improved. Going near 80 mph did not require nearly the concentration that it used to. The steering was still lighter than I would prefer and I expect the rear toe was probably the biggest contributor to the highway stability and I think the higher tire pressures gave an improvement across the board.
Before I try any alignment changes, I will see if adding 5 psi to the rear tires helps the oversteer situation, then I'll try stiffening up the front shocks a click or two. I think the lightness of the steering on the highway could be adressed by taking a thin shim from under the cap nut on the pinion housing.
Stay tuned...
-
My car has stock alignment. I found this is best for urban/highway travel. My first “belief” is that zero camber in the front increases stability on the highway by reducing side thrust on the front wheels. The rear camber is -1deg. I have also installed front wheel bearing spacers based upon the recommendation of Richard Hill, who is on the yahoo forum. I also installed alloy steel front axles
I also have SJS front and rear springs and Protech dampers. Finally, I have a 3/4” rear Addco sway bar with spring links which reduce the bar’s affect. Without these spring links, the car would oversteer excessively when letting off the throttle. I also have a 3/4” front Addco front bar. I have adjustable rear links to set the rear camber.
So, I did not take a scientific approach and do one thing at a time. However, the bearing spacer and alloy axles combined with adjustable A arms to allow setting the front camber to zero vastly improved the stability at speed. Front height is set to 6.5” (measured from the lower a arm pivot bolt) and 7” (measured from the bottom of the transmission lower link mount bracket).
My tires are Achilles 185-70/13 rear and 175-70/13 front. Pressures are 18 front, 28 rear.
I am very pleased with the stability on on the highway above 90mph ( I don’t have white knuckles afterward) and the cornering is very predictable. I have not raced it though.
I hope this helps.
-
Good information, Pfreen!
I'm hoping that beyond my experiences and any suggestions I might receive, that this thread might be a collection of owner's configurations and how they work (or don't) so we can all learn from them.
-
When it was up on the rack, what was the included angle (sometimes called KPI)?
That will tell you if anything is bent up front.
What is your rear thrust angle?
I can't compare my settings to yours as I'm running an S1, narrower tires and stock spring rates though also with the twin link. Mine drives very well. It's a bit nervous at the limit. By limit I mean when the car is trying to decide which end to let go first. Up to the limit it likes to be under power through a corner. Power really settles the car. Off throttle, the reverse.
To me, your tire pressures sounds too high. I do run higher than original spec. I run 20/28 on 175/13s.
Ride height? Mine is 1/2" lower at the front and a 1/2" higher at the rear.
-
Hi BDA,
The extra stability could be down to the amount of toe-in you've got there. In the early days of ownership I ran mine with high rear toe-in because I didn't realise/hadn't checked, and that was rock steady at motorway speeds which in those days was 80/90 (before the cops got speed cameras in their cars ;) ). Did the set-up give a toe setting per side or the overall toe ? If the latter, and based on my car shims, I'd want to check both sides had equal toe.
Can't comment on the castor because I've never measured mine and the front camber isn't adjustable so that's "stock" ;)
Those tyre pressures seem high to me. When I had my tyres fitted the guy had pumped them to 35psi because with low profiles that's what he'd done for previously on our modern cars. I drove the car but didn't like the steering on bumpy roads even at low speeds and as the only thing that had changed was the tyres, I checked the numbers. Depending on which tyre gauge I use (the foot pump reads higher) I now get 18/20 front and 28/30 rear but I suspect the lower figures are closer to reality. I would have expected 30 psi at the front to make it very light so I'm a bit surprised it feels so much better. Toe in again ?
Finally, the very crude mechanic in me set the dampers to zero for the first "round the block" runs. After a few short runs and the first spanner check I set them to half way which seemed quite firm but better. I do remember tinkering with front & rear damper settings and I'd need to check notes but IIRC they are within +/- one click from that half way setting now. If yours are the Spax with 14 clicks, I'd try 7 and see what it feels like then alter F/R to see what difference it makes.
Brian
-
When it was up on the rack, what was the included angle (sometimes called KPI)?
That will tell you if anything is bent up front.
What is your rear thrust angle?
I can't compare my settings to yours as I'm running an S1, narrower tires and stock spring rates though also with the twin link. Mine drives very well. It's a bit nervous at the limit. By limit I mean when the car is trying to decide which end to let go first. Up to the limit it likes to be under power through a corner. Power really settles the car. Off throttle, the reverse.
To me, your tire pressures sounds too high. I do run higher than original spec. I run 20/28 on 175/13s.
Ride height? Mine is 1/2" lower at the front and a 1/2" higher at the rear.
Thanks for reminding me about my ride height! Measured at the body behind the front wheel, it's 4 1/2" and at the body in front of the rear wheel, it's about 5 3/4". I was looking to get more of the S2 stance. In my notes I have that Richard suggested a difference of 1/2" between front and rear. This is obviously an area that might deserve some attention. This is lower than I've had it in the past. So far speed bumps haven't been a problem. I also seem to remember someone suggesting to me to make the lower rear link and the line between the lower front wishbone pivot and trunnion paralles to the ground. That wasn't really the aim, but that's pretty much how they ended up by my uncalibrated eyeball.
I've attached the printout of the results from the alignment rack below. Gerry didn't take the starting alignment so I've just posted the "after." Also, the colors are probably wrong because the alignment rack computer didn't have a listing for a Europa so we chose the Elan which was the closest it had.
I don't see anything about KPI or included on the printout. There is something called "Steer Ahead" which is 0. I'm not sure if that's the same.
The thrust angle is listed on the printout at 0.03°.
I recently worried that one of my front wishbone halfs on the passenger side was bent. I took them off and measured them and one was not in spec but it didn't appear to be bent (a straight edge didn't problems and the measurement from the hole for the trunnion to the pivot was correct - see attached measurement dia.) but the tube to accept the lower shock bolt was not in line with the face of the arm that is bolted against the trunnion. They should line up. When I put a washer under the tube, everything measured up correctly. Now obviously it's still not quite right or my caster would be correct but both lower arms measured (after adding the thickness of the washer) up the best I could tell. In order to get my caster, I added a washer behind the trunnion and under the leading lower wishbone half pivot to move the bottom of the upright forward. My plan is to see if I can get it closer with some more washers.
It's been a LONG time since I drove my car when it was stock but I do remember that driving 90 mph all day was not difficult. I don't remember the finer points of how it felt going into a corner or the reaction to power but it was stable enough that a nutty kid like me didn't get himself into a lot of trouble. As for now, mine seems to react similarly to yours in the turn - though I haven't tried lifting. It does tend to squat down and bite the road when you add power in the turn. Going into the turn quickly feels like it wants to swap ends. I THINK that tire pressures and/or shock adjustments might help here. I found a pretty decent article on adjusting shocks here (https://nasaspeed.news/tech/suspension/damper-tuning/).
As for tire pressures: I will say that I normally add 4 psi the the recommended tire pressures of all my cars and when I raced Showroom Stock (cars with no modifications other than safety equipment), I ran 40+ psi and as I remember it, I liked it so much that I drove the car on the street that way. I never noticed any tire wear anomalies. However, several have suggested that 30 psi is too high so lowering them will be added to future tests.
-
looking at my conversion chart (I can't think in degrees or minutes !) then I get roughly 1.5-2mm on a 15" wheel, so that doesn't seem too bad when you get the Lotus figures of 3-6mm and the rear camber looks mid range as well. I've no idea what's going on at the front, I think that's "experiment time".
I just checked the manual to see what it says on pressures and basically it's 16/24 normally with 22/32 above 100mph, both measured cold. There's even a statement about "no other reason to increase pressures" which did make me smile. 16 feels a bit low to me with low profile tyres, I've no logic behind that feeling if I'm honest other than we have potholes over here and I'd be concerned over pinching a low profile wall.
Brian
-
Reading with interest...
-
Brian,
I didn't get a chance to reply to your previous post after I wrote my last post so now I have two of your posts to reply to! :)
I think you're right that the toe-in on the rear is a major contributor to the highway stability. As I said, it's on the high side (i.e. more toe-in) of the spec. I may lighten up on the toe-in down the line to get to the least amount of toe-in I'm comfortable with.
As for converting degrees to inches in toe measurements, I use this website (https://robrobinette.com/ConvertToeDegreesToInches.htm).
The tire pressure discussion is interesting. My Honda CR-V tire pressures are 32/30 and Mercedes C230 are 28/32. Admittedly, those cars and their are VERY different from my Europa and its tires, but 30 psi doesn't seem like it would be that much out of line - which is not to say that a bit lower or even higher pressure might not be better. In any case, tire pressures, like everything else are subject to change.
I agree that 16 seems awfully low (which is what my fronts had when I drove to the shop!) and on a modern steel belted radial, where the sidewall stiffness is enhanced by the tire pressure, it would seem low pressure would contribute to "squishy" handling. Of course, lower profile tires would be less susceptible to that than the original 70 series tires.
-
Next test: I increased the rear tire pressure to 35 psi. This gave a slight improvement but wasn't confidence inspiring enough to increase my speed through a set of twisty roads near my house.
Then I increased the stiffness on the front shocks by one click. This was a good improvement. It handled better through the twisties and was very evident by the speed through them. I wasn't able to get a clean run through them but it was much more stable and confidence inspiring. The feeling the car was trying to swap ends was greatly reduced and feel through the curve was more stable.
In spite of the fact (maybe because of it) that I rebuilt my steering rack, the steering is too light.
Next test: tighten the steering by taking out a 0.004" shim from the cap nut on the pinion housing.
-
Lotus Owners manual says 18/28 psi. Generally, lowering pressure increases grip until it rolls over too much (chalk the edge to see), increasing pressure reduces grip.
-
Hi again....
From what I can see modern cars do have much higher tyre pressures than our old Europas and there's a certain logic in linking the higher pressures with lower profile/smaller sidewall tyres. I'll preface the next comment by saying "it's vague opinion, no supporting facts", so here goes;
Modern cars are mostly heavier than virtually any old Lotus from the 60s/early 70s and so when they go for lower profile tyres they need higher pressures to prevent pinch flats on severe bumps or potholed roads, and that's why my tyre guy shoved 35psi or whatever in my Europa wheels. But because our cars are so light, I've not been convinced that we need such high pressures and that's why I've stuck with close to factory spec. At one time I used to put 30psi in the rears all the time but I can't say I've driven with much more than that.
Before pulling your steering apart, I'd suggest it's easier to put a couple more clicks on those dampers. If they are ranged to 14 then you've got plenty to go at; try 7 each and see what it feels like >:D
Brian
ps - you can always click them back down very easily if you don't like it, but messing with the steering means getting dirty hands !
-
Lotus Owners manual says 18/28 psi. Generally, lowering pressure increases grip until it rolls over too much (chalk the edge to see), increasing pressure reduces grip.
Thanks Clifton. So far I haven't used anything more than feel to determine any improvement or lack of improvement. I will be testing lower tire pressures in the future. I haven't worried too much about the original Lotus documentation because I think tire construction is a lot different from when the car was stock (e.g. it didn't come with steel belted radials) and my tires have a much lower profile. My pressures were much lower for many years and I've always had handling issues. Certainly alignment differences could have contributed to them, but I started with a rear alignment done on a rack. This leads me to think that my increased tire pressure is a contributor to my better handling but so many have said 30 psi seemed high that I'm compelled to test lower pressures. When I do, I'll use white shoe polish or chalk to get a measure of it.
-
...
Modern cars are mostly heavier than virtually any old Lotus from the 60s/early 70s and so when they go for lower profile tyres they need higher pressures to prevent pinch flats on severe bumps or potholed roads, and that's why my tyre guy shoved 35psi or whatever in my Europa wheels. But because our cars are so light, I've not been convinced that we need such high pressures and that's why I've stuck with close to factory spec. At one time I used to put 30psi in the rears all the time but I can't say I've driven with much more than that.
Before pulling your steering apart, I'd suggest it's easier to put a couple more clicks on those dampers. If they are ranged to 14 then you've got plenty to go at; try 7 each and see what it feels like >:D
Brian
ps - you can always click them back down very easily if you don't like it, but messing with the steering means getting dirty hands !
I think the difference is tire construction and car weights makes comparing tire pressures on modern cars a bit problematic! :) I think trial and error with the advice of experienced people like those on this forum and local racers makes the most sense. I remind myself and readers of this thread that Richard advised me to use the following pressures F: 15-18, R: 24-26.
As for shock adjustment, so far, it seems to have made the most improvement. At the moment, I'm at 4 clicks on the front and three on the rear. That seems like fertile ground for experimentation.
The steering has very little resistance to it so it requires a lot of concentration to keep from putting more steering input in than I intend. I followed the manual when I rebuilt the rack but there was one place that seemed contradictory and that was the setting of the cap nut. The manual gives a gap between the housing and the cap nut. This impacts the resistance to turning the pinion. It also gives a resistance to turning the pinion. However the proper cap nut/housing gap does not give the proper resistance. I don't remember if I chose the proper gap or the proper resistance - I think I took something in between. I don't think I have to take the rack out to play with the cap nut. It's accessible from under the car (maybe after taking off the chassis to body closing plate).
Stay tuned...
-
Something is bent on the right front. I suspect the upright itself.
-
I hadn't suspected that - obviously - but it makes sense... What was your clue, JB? Thanks for pointing it out!
-
The fact that I had a bent one as well!
Strange there is no included angle read-out. That's how would know for sure if it is an upright or something else bent. Ask the alignment shop if they have the info and it just doesn't show up on the customer read-out.
-
Since you've been here before, where did you get your replacement and what should I expect to pay?
I'll ask them about the included angle.
-
I’m book marking this topic as I will need to reference shortly.
-
Most of the British car suppliers carry them. I got my last set from Rimmer Bros.
-
I'm a slow learner so it took me many years, and other people talking about it, for me to actually realize that with stiffer springs, you need stiffer shocks. If your springs are a little stiffer than stock, you might only need minor changes in your shocks. If you read the article I mentioned earlier, you learn that when going into a turn especially, stiffening the front shocks acts like a stiffer front roll bar - less oversteer. I am positive I am missing a lot of the finer points of shock tuning but so far it's working pretty well for me. Keep in mind that my springs are about double the stock spring rate. I think not realizing the implications to that is what caused me a lot of grief. Having springs that are not as drastically different might make life a bit easier for you. I think that the stiffer springs will ultimately yield better handling if properly tuned and hopefully that can be achieved so that I don't shake my eyeballs out of my head. So far, I'm optimistic.
-
Most of the British car suppliers carry them. I got my last set from Rimmer Bros.
Thanks, JB. I'll look them up.
-
Here are PSI manufacturer recommendations from Toyo for their tires. Tire pressures change based on the weight of the vehicle. There are suggestions how to help oversteer and understeer. Of course PSI ratios should be altered for mid-engine cars. But the Europa is definitely in the under 800 kilos and those PSI numbers are low.
-
Thanks for posting those details, I've not seen that detail about pressures/weights written down before. It does explain why 30-35psi seems to be the norm these days with a lot of modern cars being over a ton and heavier.
Brian
-
Great post, L'madness! It appears I and some of my friends had it backward on pretty much every point back in the day! I'll adjust accordingly.
-
Thanks! BDA, I would definitely A/B your TCS mechanically to Pfreen's car who generously posted his specs on this thread. I've ridden with him in his car at +80 mph speeds and his car is incredibly stable. I've also observed his car from my car on the road while driving in several local rallies and caravans. It is solid and stable. Pfreen won't dote praises on himself, but he is a retired automotive engineer who worked for both Chrysler Corp. and BMW (and almost worked for Lotus). He holds several automotive patents while working for BMW. He has helped me make several improvements on my car that substantially improved my car's handling.
-
My next concern was the lightness of the steering. It felt so light that when going down the highway, it took a bit of concentration not to move t he wheel which was very sensitive. A small steering input at speed gave the feeling that disastrous results were imminent. I thought this was a good time to try to tighten up the steering.
I have recently rebuilt the rack from (lightly) used Spitfire parts. The manual gives a procedure for getting the proper stack of shims under the cap nut to give the correct resistance for turning the pinion. Then they give the spec for how much turning resistance you want (2# on an 8" arm on the pinion). In my case, doing the first did not give me the resistance I was supposed to want. In the end, I think I went with the resistance regardless of the shims required.
Last night, I fooled around with shims to get more resistance. In the morning, I went to the local MG club breakfast and found that the steering was way too stiff. I reshuffled the shims to get to the next taller increment in shim height to loosen it a bit. I can't be sure, but I suspect that I'm back where I was after I rebuilt the rack but I'm not positive. While I did that, I gave the front shocks one more click (F: 5 clicks, R: 3 clicks).
The result was more improvement in all aspects. My speed and comfort in a twisty section were increased. Highway driving at 80 mph or more was a bit more stable. The surprising thing is that the steering seemed to be a little heavier also. The steering was less nervous and twitchy. I should also say that on normal roads, the stiffness in the suspension is noticeable but not bad at all. As you might bumps that are a "problem" are starting to get smaller. Also as I say, I can't be sure my changes to the shims under the rack cap nut but this effort really began when I read some posts on the yahoo group that cured their highway stability issues on their car with stiffer springs by stiffening the shocks so I don't discount it.
Future plans: There are some alignment issues I may address soon. Pfreen's earlier post saying he runs 0 camber in the front intrigued me. Clifton and I have been discussing things via email and his front has less camber than mine but more than Pfreen's. I'll probably try splitting the difference. As JB said, it's likely that I have a bent passenger side upright. I wouldn't dispute that (and I haven't gotten around to asking the shop that did my alignment if their rack measures included angle) but one of the benefits of having the car since new is that you know the history and while there was a hit on the driver's side front, there was never anything on the passenger side front so it seems unlikely. I wonder if I could possibly have the uprights switched and the original driver's side upright is now on the passenger side. In the mean time, I may see if I can get more caster on the passenger side without replacing the upright. At some point, I will go back to lower tire pressures but more immediately, I will experiment more with stiffening the shocks. I'm thinking my strategy might be to stiffen the front till I get some understeer (or it's just too stiff) and then I might experiment with the relative stiffness between the front and rear as well as the absolute stiffness. Another thing I'll be doing is setting less toe-in for the rear.
Don't touch that dial!
-
I think you could go more on the dampers although it's a long time since I had any Spax dampers so I'm not familiar with the total damping forces available, I'm just guessing based on the 14-click range.
If the primary job of the damper is to reduce the spring oscillation then it seems to follow that a stiffer spring will need more stopping power and hence stiffer dampers.
I don't think there's anything wrong with starting at zero and working your way up but I'm less patient. I drove mine with nothing on the Protechs and then took them half way with the intention of the next drive being full stiffness. After the second run I decided it wasn't bad for the roads I drive on and didn't feel I needed more so I never bothered with the final setting.
The principle of getting three points on the graph at zero, middle and top so you know the full range available and how it relates to driving doesn't seem unreasonable even if the full setting shakes your fillings out.... (at least you'll know not to go there again ;) )
Brian
ps I'm also intrigued by the zero front camber comment and would like to understand why it's beneficial. I could see how it might make the steering lighter but I was hooked by the comment that it improved stability at speed. Simple explanations please !
-
Yeah, the old binary search principle! One of the fastest ways of searching an ordered list is to go to the middle and test. If your target is lower, go to the middle of the lower part of the list or the higher part if higher and test and repeat till you find it. I don't really have a good reason not to do it that way but I think I want the lowest dampening that works. I think I want to sneak up on it, too. And then I don't KNOW there are 14 clicks. The Spax guy wasn't sure.
I'm familiar with the idea of what dampers are for and it should have occurred to me earlier but the car didn't bounce or otherwise give me any of the standard reasons to suspect the shocks, and then In spite of the fact I did some racing in my past I never explored monkeying around with suspension settings and then the shocks I used were not adjustable.
I think you're going to have to ask Pfreen about his 0 front camber setting. He mentions it in a previous post on this thread. Clifton said he uses 3/4 degree all around and he says his car is stable at 125.
-
I didn't invent 0 degrees of front camber.. It’s in the manual. 0 deg+-30’.
Camber is good for cornering since the goal is to maximize the tire contact patch area. I know others set their cars up with at least 1 deg negative for autocross. I believe them. That doesn’t necessarily make it good for expressways. I used to have mine set up with 1 to 1.5 deg negative front camber and per spec front toe. High speed stability was terrible.
Also, tcs Europas, at least Literary’ s and mine, required almost a 1/4 “ of washers per side to bring the rear toe into spec.
Handling is not my expertise, in spite of what Literary man said. I only wrote what worked for my car.
I basically set the car up as standard alignment, but lowered, with hopefully consistent , solid bearings and suspension.
The book, “How to make your car Handle” by Fred Puhn by hp books is a great reference, if you all are interested
-
G’day BDA,
Looks like you’re making some inroads (pardon the pun) on this.
Front camber can be tricky, I reckon, but it’s also needed less with stiffer springs.
I’d set front camber to 0º.
Reduce front toe to a poofteenth (engineering term).
Raise the front ride height perhaps 1/2”.
Go up another two clicks on the front dampers and leave the rears alone for now (though I do like EuropaTC’s method of taking big handfulls of clicks to establish a pattern).
All those should help the car to wash off some of the corner entry oversteer and make it easier to drive as well. And all within specs too, if I recall.
I’ve lost track but what tyre pressures are you currently at?
-
Hmm, you rebuilt the rack... did you shim the inner tie-rods correctly? If they are not under proper tension, they will "steer" the car as they load and unload.
-
Thanks Gavin. I think I'll do my posts after a few tests. I guess after a while it seems silly to say that I made one small change and here are the results. I forgot to say in my replay to EuropaTC that the other reason I'm sneaking up on it is I am sort of feeling my way in my darkness here! :)
JB. Yes I did rebuild my rack - more than once! The first time (they all weren't complete rebuilds), I didn't pay attention to the tension on the tie rods you note and you didn't have to go very fast before it would try to jump into the next lane on the slightest steering input! It was diabolical! The second time, I estimated the tie rod tension and when it still didn't feel right (actually, some of that feeling was probably due to the shock/spring situation), I rebuilt the entire rack. I got a 40,000 mile old Spitfire rack basically adding the Lotus bits to it because it was in such good shape. This time, I used a trigger gauge (basically a spring scale) to test the tension on the tie rods and I made an 8" lever to press on the pinion splines to test the tension on it. Old racks end up being compromises when you set up the pinion resistance because the center ends up being a little too loose and the ends end up being a little too tight. I think what I have now is about as good as it's going to get.
-
Oh, I dunno, BDA.
Sneaking up in the darkness never worked on the girls I went out with. :D
Just on the off chance, when swapping over to the Spitfire rack, presumably you also swapped the correct TCS tie rod sleeve nuts to the rack as well?
-
Yep! The tie rod nuts, the tie rods, the tube to limit the amount of steering input, and the extension for the rack housing.
We went out with similar girls! ;D
Edit: I forgot to mention the tie rods!
-
Hey DBA,
I've been working on tuning my suspension for a while, so I'll pass on what I've learned so for, keeping in mind my car is used almost exclusively for autocross and track days.
Bit about my car:
Tires - 185/60/13 Hoosiers
Shocks/Springs - AVO adjustable
Adjustable front sway bar (had an adjustable rear as well but removed it)
Front toe - 1/16"
Rear toe - 1/8"
Front camber -2.4 deg
Rear camber -2.2 deg
Front pressure - 22lbs
Rear pressure - 24lbs
After each run I use a Longacre probe pyrometer to take tire temps which has been invaluable for tuning setups.
Like you have had people recommend higher tire pressures, and I've tried on multiple occasions (clear up to 35lbs). Though in my experience there's a lot less grip at higher pressure. Also when I've tried lower pressures the tire tend to roll too much and heat up the outsides. I also bleed off pressure right before running so that I always start 22/24 (unless I make adjustments based on the pyrometer readings, though usually not more than 1.5 lbs up or down).
The toe is going to make the biggest difference as far a how stable the car feels. Running 1/16" in front does make the car a bit darty, though that works out great for autocross (for street use I'd probably bring it up to 1/8"). I've also found that running less than 1/8" rear makes the car a bit unstable at high speeds or very hard braking.
As far as shocks, start on the softer side and work up as needed. Currently I probably have my car stiffer than ideal, though I've been trying to reduce the amount the front inside tire lifts when accelerating out of a tight corner.
Anyway, best of luck (and highly recommend a good probe pyrometer)
-
Great information to chew on, JPS! You wouldn't know your spring rates would you? Any notes on shock tuning?
I've been concentrating on tuning the shocks lately. So far that has had the biggest change. Currently the front is at 9 clicks and the rear at 3. On the highway, its better than it's ever been but in small steering inputs make the car feel like the front is very stable and the rear seems to pivot from the front. I'm thinking that some more stiffness in the rear shocks might be in order.
I'm not sure I'm going to go as far as taking tire temps as I don't expect to track or autocross my car. I just want it to feel comfortable when I push it in a corner or drive on the highway.
There are lots of things I want to try but I haven't been able to devote the time to it I would like. I'm also on the lookout for a twisty road to test on. The one I use now is very handy and near my house but if I loose it on one side, I got into woods and maybe into a ditch. If I loose it the other way, I'm in oncoming traffic!
-
BDA Good luck with dialing in your TCS. Can't wait to hear the details. Here is an interesting cross-reference chart on understeer and oversteer.
-
Thanks, 'Madness! That's a nice chart to keep handy!
-
Lotusjps What spring rates do you recommend for autocross?
-
I did some more experimenting over the last several days. As I mentioned in an earlier post, I set my front shocks up four more clicks to 9. That helped a lot with oversteer - though there is still a lot more than I want. Highway driving was better again but still sensitive to small steering inputs, though not as much as it had been. Small steering inputs made the car feel somewhat like a pendulum. The front was the pivot and the rear wanted to step out a little. 80 mph required your attention but was a lot more relaxing than it had been - especially before I had started monkeying with the shocks.
I added 2 clicks to the rear shocks and that was an improvement everywhere. I don't know that I was faster through the twisty road I was testing on, but it feel a lot more stable. On the highway, it was a big improvement again. It was more stable and again less sensitive to small steering inputs. When I turned the wheel a little, it was much more comfortable and the pendulum feeling seem to be pretty much gone. I still had more oversteer in sweepers, such as highway on ramp, than I liked.
The latest test was to lower tire pressures. I have forced myself to only change one thing at a time and I figured that tire pressures would probably produce less change so I waited till the car was pretty good before changing them. I was running 30 in the front and 35 in the rear. I lowered them to 22 in the front and 24 in the rear. Everything was better still. There was a bit less oversteer on the on ramp but still more than I wanted.
It's a lot more fun to drive now. There's still room for a fair amount of improvement - especially in reducing oversteer. I'm not excited about stiffening the front shocks any further because it's starting to impact the ride quality.
-
When you say oversteer. Are you saying the rear is loosing traction and sliding to where you have to steer it back straight? I ask because they understeer from the factory as most cars, especially mid engine ones for safety reasons.
-
Yeah, the normal thing is to default to under steer but then I don't have a normal Europa, at least in terms of springs, ride height, wheel & tire size, and shocks.
Well, I didn't let it get as far as having to correct but you can feel the rear end try to swing around. I didn't want to push it that hard and potentially lose it entering a freeway! It is definitely not under steering. I wish I had a place to test that wasn't on city streets!
I'm open to any suggestions. This is what I'm thinking about at the moment:
I could reduce rear tire pressures a little, increase rear negative camber, lower the rear, or reduce rear spring rates. However, my tire pressures are 22/24 so reducing the rear would bring it equal to the front or lower, increasing rear negative camber would make it greater than -1°. Both of those seem out norm from what I've been reading. My ride heights are F: 4 1/2", R: 5 3/4". That's lower than most TCs I've heard of and the rear is higher than the "1/2" higher than the front" Richard suggested to me. Playing with ride heights may be something to look at. As for changing the rear springs, I do have a pair of 100# rear springs I could swap for my 130# springs...
-
My ride heights are F: 4 1/2", R: 5 3/4". That's lower than most TCs I've heard of and the rear is higher than the "1/2" higher than the front" Richard suggested to me. Playing with ride heights may be something to look at. As for changing the rear springs, I do have a pair of 100# rear springs I could swap for my 130# springs...
I don't think it's the springs at fault, our cars are fairly similar and I'm running 160lb rears which gives wheel frequencies of 1.8/2.0 (F/R). On the same spreadsheet assumptions the S2 has OEM values of 1.1/1.4, the TC 1.2/1.4 so they also had a lower front ratio.
I started off with 1.8/1.8 and that didn't feel right so I increased the rear springs, aiming for similar balance to the OEM cars. I can't say the improvement was only down to the springs because I also moved the ride heights as the front was very low and I felt there was too much rake on the car. I also changed damper settings so again, it might not be just a spring thing.
If you change to 100lb springs then it will certainly alter the rear grip but on the same basis as the previous calcs I get 1.8/1.6 F/R ratios which sounds contrary to what Lotus did.
Next - where are you measuring ride height from ? If it's chassis based then that sounds like a lot of rake but to be fair I've no experience of such an angle.
Measuring under the front chassis cross member I have 5.875", at the rear of the central spine just before the "V" I have 6.125" and the rear hoop is 8.625". The latter might not be relevant to yourself because we have different gearboxes and presumably different rear hoops ? I have a garage pit so can measure from the chassis easily but it's also possible with old fashioned external calipers, lying down & stretching your arm underneath to get a rough idea of where you are.
Unfortunately I didn't record the initial settings (no idea why not :confused: ) but the earliest numbers I have for the three locations above are 5"/6.5"/10". I went through several permutations up to 6"/6.5"/9" before ending up at the ones I have now.
I've never successfully figured out where the F/R roll centers are on the car but I'm wondering if because there's 1.25" higher at the rear (4.5"/5.75") then the rear roll is too high compared with the front. Don't know and I've no idea how critical that aspect is on our cars so that last sentence is just me rambling..... ;)
Brian
-
BDA: Based on the chart I posted, raising the front-end height would reduce oversteer. I think getting closer to that recommended 1/2 inch differential between your front and rear height might reduce the oversteer. It is certainly worth a try.
-
"I wish I had a place to test that wasn't on city streets!"
http://virnow.com/experience/club/ (http://virnow.com/experience/club/)
Not far!
-
My ride heights are F: 4 1/2", R: 5 3/4". That's lower than most TCs I've heard of and the rear is higher than the "1/2" higher than the front" Richard suggested to me. Playing with ride heights may be something to look at. As for changing the rear springs, I do have a pair of 100# rear springs I could swap for my 130# springs...
I'm inclined to agree with 'madness' but go a little further to ensure the difference is noticeable and also significant.
So . . I'd set both F and R ride height to be the same.
You can always retreat back to the usually recommended 1/2" difference, but as you say, your car is different and that may not apply as readily.
-
Brian, you're way ahead of me on wheel frequencies. Other than possibly using them to guestimate damper settings, I'm not sure what their significance is. I did a little bit of poking and found how to calculate it but nothing that explained much more than that! I did see that it requires you to know your unsprung weight. I'm not about to take my rear suspension apart (again) and weigh all that stuff! As analytical as you are, I guess I shouldn't be surprised that you figured that out! :) I did calculate the rear spring rate that would be the same multiple as 250 is to the stock front spring rage and it came to 160# so I guess that is another way of getting to the same thing. I think you're right that the 100# springs are not the way to go.
I'm not sure I can measure the ride height at the frame. Reaching under that small a space and operating a tape seems impossible - or I'm too lazy to try - so I went the easy route and measured at the body behind the front wheels and in front of the rear wheels.
I think everybody is right (and it seems so obvious now!) that the next move would be to work on ride height. I really like the way the front looks now - It was such a shame that head light regulations required the TC's nose to be set so high! - so I think I'll try lowering the rear a bit. I've intended to measure the camber change of the rear through it's travel. Determining the roll center would also be a nice project.
Andy, I've thought about taking my car to VIR or even an autocross. I'd have to borrow a helmet and then I'd have to get head and helmet into the car in such a position that I could drive! Even with the bump in the roof, that may be a tall (I couldn't help myself) order, but might look further into that.
Thank you, everybody, for your input!
-
When we talk about ride height, I think we need to be consistent. BDA, you referenced in back of front wheel and in front of rear wheel. I use the front lower A arm pivot bolt and the transmission lower link bolt for the rear.
I just measured what my car is set to for all four points.
Front A arm bolt 6”. Behind front wheel 4.25”
Trans Lower link bolt 6.5”. In front of rear wheel 6.25”
So, I think my ride height is close to BDA’s, and slightly lower than the ride height referenced in http://www.lotuseuropa.org/LotusForum/index.php?topic=1104.msg19964#msg19964
I personally think the lower link and A arm pivot bolts is the most consistent since we know the fiberglass bodies could be slightly different.
-
I couldn't agree more. Brian has made the same point at least to me. Using the body is OK when you're comparing heights on your car but Lotus quality control being what it was and the fact that we jack the car where we're measuring and that could cause problems, measuring at a hard point is a better reference when it might refer to other cars. I'll try to remeasure using your points and post the results.
-
Brian, you're way ahead of me on wheel frequencies. Other than possibly using them to guestimate damper settings, I'm not sure what their significance is. I did a little bit of poking and found how to calculate it but nothing that explained much more than that! I did see that it requires you to know your unsprung weight. I'm not about to take my rear suspension apart (again) and weigh all that stuff! As analytical as you are, I guess I shouldn't be surprised that you figured that out!
I know very little about frequencies other than how to do the sums and a very rough guide as to what the numbers feel like in practice on my own cars. For example, the original Elan was 1.18/1.34 and that was noted for it's soft suspension whilst still handling well. When I modified mine I spoke with Pat Thomas, a UK long time Lotus dealer who has raced Elans and he asked about how & where I wanted to use the car. The end result was that he recommended a set of springs/adjustable dampers which gave 1.8/1.93 rates which gave me my second rung on the ladder of how the numbers feel in practice. (as an aside, the Elan is now absolutely brilliant, I love it all over again !)
So my take is - up to 1.5, soft, comfort. 2-2.5 feels like a modern sporty car and is probably as far as I'd want to go on the road because the springs & dampers are going to get harsh on potholes, uneven surfaces. Above that you're looking track cars and I've no idea what the upper limits are or do.
Second thing is the F/R ratios. There's internet opinions that you should have them identical and others that say you should have different rates. When you hit a bump at speed then the F will bounce first and be in a cycle when the rear hits the bump and starts it's own cycle. If they are slightly different the theory is that the car stabilises better than with F/R identical rates, whereas I've seen plenty of views saying when you're on high rates it doesn't matter.
I decided initially to follow the "same both ends" and went for 1.8 all round. I didn't like it and hence where I am now, 1.8/2.0 which (doh) is a similar relationship to both the OEM Elan & Europa and Pat's modified Elan settings. Sometimes you have to stick your hand in the fire to see if it's hot.
I'm not sure I can measure the ride height at the frame. Reaching under that small a space and operating a tape seems impossible - or I'm too lazy to try - so I went the easy route and measured at the body behind the front wheels and in front of the rear wheels.
As I said, I can get into the workshop pit and roll the car over me to measure heights but mostly I use internal calipers, photo attached. It's very easy to get them roughly right, lie down and reach under the car to the chassis central spine and adjust the screw thread to take a reading.
Brian
-
Thanks Brian! That helps me understand some of the frequency business. As you Brits say, everyday is a school day!
When you said you had a pit, it became obvious how and why you chose the center of the frame for your ride height reference point. I am jealous of people like you who have a pit and Certified who has a lift! Both are pretty much impossible in my garage. :(
-
This is all quite interesting to me. I haven't driven my car in a coon's age (or longer), but I will. My recollection is of a lot of understeer; feeling like maybe there's no weight in the front of the car keeping the tires on the road. But I haven't checked-out anything, not even tire pressures, so lots of good food for thought here.
Brian: do you have a suggested place to get instructed about how to estimate the natural frequencies of the suspension? In other words, "how to do the sums".
Also:
When we talk about ride height, I think we need to be consistent. BDA, you referenced in back of front wheel and in front of rear wheel. I use the front lower A arm pivot bolt and the transmission lower link bolt for the rear.
So I understand clearly, is this to the centerline of the bolt?
-
The centerline of the bolt would probably be the best reference point. I haven't been able to measure mine yet so I'll see what's practical. I might even try using my inside calipers like Brian!
-
Centerline of the bolt. Again, look at europaTC’s post in http://www.lotuseuropa.org/LotusForum/index.php?topic=1104.msg9212#msg9212. It shows where he measures from. This is where I also measure from.
-
Well I gave my inside calipers to a buddy but I was able to measure my ride heights with a scale. I'm at 6.5" in the front and 6" at the rear (measured to middle of the inside suspension pivot bolt).
Brian, what were you unsprung weights? Did you actually measure your unsprung weight or did you use a value that you found?
-
Brian: do you have a suggested place to get instructed about how to estimate the natural frequencies of the suspension? In other words, "how to do the sums".
There's quite a few websites around these days which cover suspension calcs and it wouldn't surprise me to find an online calculator now. I started with a book by Alan Staniforth on "Competition Car Suspension" but there are many others and these days they tend to be easier going for someone starting out. You can even get the basic maths from the internet with some google searching - just try "suspension calculations" and you'll be inundated ! example: https://eibach.com/us/p-101-suspension-worksheet.html (https://eibach.com/us/p-101-suspension-worksheet.html)
I've added a cut down version of my spreadsheet as an upload because the last sheet contains all the maths formula you'll need for a basic stab at it. This isn't complete because you should consider the antiroll/sway bars but for what I was doing I wasn't bothered. The other caveat is that it contains assumptions which may/may not apply to your car. As I wanted to compare OEM with new setups it didn't really matter because I was looking at differences in rates with the same car, not trying to get an absolute number.
A rider on the measurement points. Yep, I have used bolt centres but the dimensions given earlier on this thread refer to the floor/chassis spine distances. The reason I moved to that was because I wanted to get a feel for the downward angle of the chassis and felt the chassis measurements over a few feet were more reliable than trying to work it out from bolt centers. (I don't know the relative heights of the lower wishbone bolts and the inboard rear lower link bolts)
Whatever you use doesn't matter as long as you are consistent because you've got relative numbers directly relating to your car.
-
Thanks, Brian! I think you sent me the full version of that spreadsheet a while ago so I'll be looking closer at that.
Was the value for "Wheel Weight (per axle)", row 7, observed? If I add the last three values in the "Unsprung Weight Data", I get less than the 72# found on row 7 so I'm assuming they are observed.
I agree that all the ride height references points are valuable if we're talking about the same car. I think that Pfreen's suggestion to use the center of the inboard lower suspension bolt as a reference is a good idea when talking about this on the forum because it is pretty easy to measure and eliminates a lot of manufacturing variables. Measuring at the center of the frame 'T' is not a simple operation for those of us without a pit! :)
Serge posted this link that looks like a nice calculator several years ago (http://farnorthracing.com/autocross_secrets16.html). I haven't tried it yet but it looks interesting.
-
Was the value for "Wheel Weight (per axle)", row 7, observed? If I add the last three values in the "Unsprung Weight Data", I get less than the 72# found on row 7 so I'm assuming they are observed.
:-\ hmmm, it was a long time ago, which is another way of saying I can't remember :)
I do remember weighing all the wheels on bathroom scales and also the latest discs/calipers. I can't be sure but I think I guessed the weight of the rear calipers and said "about the same as the front". I don't think I weighed the rear hubs because I'd have had to dismantle & don't remember doing that. The angle for the front springs I do remember measuring but the rear I just said "90deg" and didn't bother checking if it was 90 or 88, at that point it doesn't make much difference.
Vehicle weights and F/R balance came from road test data, I went through a couple of Brookland's books and took an average.
As I said in the disclaimer, there's some assumptions in there so don't take it as absolute truth in the calculated numbers.
Specifically on Row 7, I guess you're looking at HTU's columns and that's 2x36lbs for the MGF alloy wheels. I ran the 56lb in Row8 (2x (13+15)) across the lot, accepting that the OEM car wouldn't have had those front discs and would have used rear drums so there's another assumption/inaccuracy.
If you accept that you're looking for comparisons, being a few lb out doesn't make that much difference, you'd need 50lb or so to notice. For some reason I didn't weigh the 205/50x15 on the rear tyres but used the weight for the 195's. It's probably 2/3lb heavier per wheel but if you change the 72lb for 80lb it won't make any significant difference.
Brian
-
It's been a long time since I've updated this thread. The short of it is that I've increased my shock stiffness quite a lot. Without being able to find the settings I last mentioned, I'm up to 11 clicks in the front and 9 in the rear. You would be forgiven for not remembering that the SPAX tech guy told me that I may have only 14 points of adjustment. I'm thinking that I actually have 24. Turning the adjustment screw is pretty easy and when I made my first adjustments, I could hardly detect the "click." That leads me to believe that the clicks will get harder to make and that at the top of the adjustment, the tension on those clicks would be pretty stout. If you have experience in this, please feel free to chime in. Anyway, I will be going stiffer yet (after I get my turn signal situation squared away). The increased shock stiffness has made my car more stable at highway speeds and not uncomfortable to drive. However I think there is more to be gained. One day, I will do a study of the suspension geometry and wheel rates and all that fun stuff but that will have to wait for a while.
The real reason I'm making this post is to attach a table of handling characteristics, causes, and effects I shamelessly transcribed from Carroll Smith's book, Tune to Win. Of course the emphasis is on race cars so there is a lot that most of us wouldn't car about but then there are some of us who do race. I hope it's useful to someone.
-
BDA: I don't know if you have the same Spax as me, but I have the krypton gas ones from R&D which actually have 28 clicks. According to the brief two page manual from the Spax website, you adjust in increments of four. Maybe the tech guy was thinking in terms of double click adjustments and that is why he said 14 levels. I have my front set at 16 clicks. I have Protechs on the rear set halfway. And thanks for posting that chart.
-
I got mine back sometime in the later '90s and I don't think I have the documentation that came with them anymore (but maybe I should look through my papers because I wouldn't have thrown them away on purpose). I have emailed with SPAX tech support and he wasn't sure if I had the older shocks with 14 clicks or the more modern ones with 28. In case you don't remember from earlier in this thread, I have 250/130 springs. It sounds like your springs are similar.
-
BDA: I just recently replaced my rear shocks and had them sent pre-loaded from Barry Spencer from Spencer Motor Sports. Barry is a factory-trained Lotus Technician who worked in their engineering department. He is SCCA Solo 2 champion and he one it in a highly modified Europa. He sets up any older model Lotus for racing. I went for his Autocross suggestion of 150 lbs in the front and 120 lbs in the rear. Paul (Pfreen) uses 250 lbs. in the front and loves them. I lowered my rear to 6 inches. My front is 5 1/2 inches. It handles fairly neutral. I think this thread you started has been one of the most useful for guys who want to really dial in their Europas.
-
Well, that's very encouraging news and it sounds like there's more to come. My dampers are relatively stiff with similar springs so if you are 11/24 & 9/24 (or 28 ?) then I'd bet there's a few more clicks to go before you start to become unhappy with the ride.
I haven't had Spax dampers in a long while, in fact it probably dates back to the late 70s/early 80s so memory is definitely hazy but I do recall that adjusting the screws felt like there was no real resistance. I can also remember getting confused where I was with them, which probably explains why I've never had any since !
Great post on the chart. I haven't read that book, what's your overall opinion because from that chart it sounds like something I ought to get ?
Brian
-
Things are definitely going in the right direction.
You can do a search for "Carroll Smith" and see the books he's written. They are all still in print. I only have three of them and I have to admit that I have not taken nearly full advantage of the information in them (that's obvious by the fact that it took so long to get where I am with my car's handling!). They have a wealth of practical information but, of course, it is centered on race cars but there are lots of intersections with street cars.
Prepare To Win is about preparing a race car. It goes into topics as plumbing, basic metal work, welding, suspension bearings and bearing installations, suspension alignment, electrics, instruments, and fuel cells and more. It's a practical primer on putting together a race car so it discusses safety wiring, aircraft hardware, throttle linkages, etc. and even discusses records, paperwork, and organization.
Tune To Win was more about tuning what you built in Prepare To Win. There are chapters about the racing tires; weight, mas load and load transfer; suspension geometry; steering geometry; rates and rate control - springs and anti-roll bars; cooling; handling; and several other topics. The chapter that analyses suspension walks you through slip angles and their effects and goes into cutting out paper dolls (paper representations of the suspension) to graphically show you what happens at different roll scenarios. At some point, I plan to get more into that.
Nuts, Bolts, Fasteners, and Plumbing Handbook is really more than what it sounds like. In Prepare To Win, Smith discusses different aircraft bolt and nuts and when to use them, but in Nuts, Bolts, Fasteners... he is more analytical and discusses the characteristics of metal; stress, strain, load, and fatigue; thread physics; bolts and bolted joints; female threads; locking devices; washers; high performance plumbing; and more. There is stuff about different bolt and nut specs, information on some pretty fancy bolt/washer/nuts, failure analysis, threaded inserts... It's more analytical than his previous two books but there is some practical information. Interestingly, he says that he wanted to name this book Screw To Win but I think his publisher talked him out of it!
As I say he has other books that sound interesting to me and maybe to you too. He has a wealth of knowledge and his style is informal and easy to read. I wouldn't sell myself as any example, but I try to follow his general advice when I can. For example, I try to safety wire any bolt that does not have a lock nut on it (I readily admit that some are just too hard to get to so I fall short sometimes!), but I like aircraft bolts and I use them whenever possible. I was about to say it's overkill - and I guess the cost is - but I like the fact that they have a grip length meaning that the threaded portion is not in shear if sized correctly. They are made of steel that is similarly strong as a grade 5 bolt but because you don't have the extra stress risers and reduced diameters from all the threads in SAE bolts, they are actually stronger in practice.
If you're just interested in exploring the handling and analyzing your suspension (and it seems you've already done some work in that regard), I would advise Tune To Win. Prepare To Win is a great reference on building a car. The Nuts, Bolts, Fasteners... book is probably more information than a hobbyist car enthusiast would need.
-
BDA: Just ordered Tune to Win. Gratitude for the info. I am an information junkie. His Engineering to Win has a Lotus Formula 1 on the cover. Once again, this has been a tremendously insightful thread.
-
Now that is what I call a book review, you ought to be on commission !
I don't think I'd go for the "Prepare" book because I'm not about to start building anything and I doubt that I'll need the high tech approach of "Nuts, Bolts, etc" but the "Tune to Win" sounds very much up my street. I have a few books on suspension design and realise that they all cover the same basics but there's something about reading a different author which often gives me a slightly different or deeper understanding and always reinforces what I've already learnt.
That's something else on the "to buy" list.... :)
Brian
-
If you're just interested in exploring the handling and analyzing your suspension (and it seems you've already done some work in that regard), I would advise Tune To Win. Prepare To Win is a great reference on building a car. The Nuts, Bolts, Fasteners... book is probably more information than a hobbyist car enthusiast would need.
Regarding the nuts, bolts and fasteners book, I have a question that is going to expose me as a total newbie at auto repair: When do you use Never-Seez/Copaslip type anti seize goop and when do you use Loctite type thread locker? I'm thinking mostly suspension components, since that is my next project, but also high and low temp engine components and basically everywhere. Does anti-sieze diminish the holding power of Ny-loc nuts? Would Loctite be unnecessarily redundant with Ny-loc nuts? The two products would seem to be at cross purposes to each other, but I want my parts to come apart easily in a few years, but I also don't want them to shake loose. Thoughts?
Tom
-
Hi Tom,
It's always better to ask what you might think is a dumb question than to make an even dumber mistake !
Personally I don't use thread lock or even anti-seize compounds on nuts/bolts and I know that might be a controversial statement to make. Nothing wrong with either compound, I've just not considered it needed on my cars. One thing that irks in my mind is how much (if any) an additional compound makes to the torque loading on a critical item. I know we did tests with dry bolts and various lubricants when I was working and some made a significant difference although it's probably down to the amount you use.
I use nylock nuts on either new or wire-brushed dry bolts and when tightened up correctly they've been fine. If it's something I consider very critical and where I know I won't see the assembly under normal conditions (like the front of the trailing arms) then I've added a split pin outside of the nylock, drilled after tightening. Whenever I've checked the pin is still "loose" so ostensibly it's been a waste of time, but that bolt slackening off could easily go into toe out which you really don't want, so I feel happier with a pin there.
I do put grease or waxoyl (a waxy underseal) all over the final assembly and don't normally have problems undoing things later.
Brian
-
I don't think anti-seize will seriously degrade the nylon locking but I would expect that that it would diminish it a bit. Some people use anti-seize on every bolt and nut (IIRC, Certified is in that camp). I don't. It's not that it's not a good idea, but for a car kept in a garage and gets very limited exposure to rain, I don't think it's really necessary. That will ensure that the two won't get rusted together - something most people who wrench on old cars has cursed. Anti-seize is also very good to use on spark plugs in an aluminum head. One place I've used it recently is on the conical face of my lug nuts. I have conical lug nuts that mate with steel inserts in my wheels. When I was torquing them I felt the nut grab or drag against the insert which would give me a false torque reading. I did not put it on the threads. Torque values are usually assumed to be taken on dry fasteners, putting anti-seize on the threads and torquing to the same value would impart more tensile stress on the stud than a dry reading (part of any torque reading is the torque required to overcome the friction of the threads sliding against each other). For that reason, unless a wet torque spec is listed, I would not use anti-seize or other lubricant on a torqued fastener, but I would ensure the threads are clean.
It makes no sense to use loctite and anti-seize together. I use blue loctite when there is no other locking mechanism such as a lock nut or safety wire and I will want to be able to take that joint apart without a lot of drama. I know lock washers can work but Mr. Smith has convinced me not to rely on them unless I have no choice. I use red loctite on things I never want to come apart. It will require heat to undo red loctite. I think I read in Prepare To Win that there is actually a primer or a preparation product that is supposed to be used before using loctite, but I just use lacquer thinner when I'm motivated and a clean rag when I'm not. I advise using lacquer thinner, not the dry rag.
Prepare To Win is a good reference for things like this. Of course, he is writing for people wrenching on race cars so they don't normally have to contend with rust, but Mr. Smith explains a lot of assembly practices that are applicable to our situation. I probably should reread it.
-
If a bolt slides through a bore, you should use anti-seize on the shank of the bolt. Especially if the bore is a dissimilar metal. A good example would be the long bolts through the rear uprights. Also the upper pivot pin in the front suspension.
You should always use ant-seize with SS fasteners to prevent the threads from galling. As an aside, never use ungraded SS fasteners as anything but ballast.
Thread locking compound only works on clean, dry threads do you can’t mix anti-seize and thread lockers.
Whether you should use anti-seize on “everything” depends on your local climate. Wet climates result in significant corrosion issues while dry climates may have practically none.
-
I'm reviving this thread since I have continued to experiment (at a leisurely pace, unfortunately). Maybe everybody has gotten all they need or want from the thread up till now. I'll post this in case anybody might find it useful or entertaining.
If you go back to the beginning of this thread, you'll see my spring rates are F:250#/R:130# and that there was some question about how many adjustment steps my SPAX shocks had. One tech support guy I emailed wasn't sure if it was 14 or 28. Another said it was 14. Well, I got the front shocks up to 13 and still felt I had too much tendency for the car to try to swap ends (colorful term for oversteer), so I adjusted it another two clicks stiffer. It didn't feel any different going from 13 to 14 than from 14 to 15 so I'm guessing I have more adjustment than 14 clicks! I adjusted the fronts to 15 clicks. I had adjusted the rears up to 12 clicks because I theorized that what I felt was an oversteer might actually be a symptom of the same thing that causes the car to "wander" at highway speeds. This seemed to make it marginally worse in the turns so figuring that was caused by the greater roll resistance, I back down on the rear shocks to 9 clicks which was better.
Since the easiest adjustments I can make are shock adjustments and alignment (changing roll stiffness would require either different springs are fabricating and fitting a new anti-roll bar), I felt like I'd gotten pretty much at the end of my shock adjustments. I had a pair of 100# 13" springs lying around so I figured I'd replace my 130s with them. I raised the spring perches a half inch (I should have calculated it because to keep the same ride height in the rear required a 1.1" rise in the spring perches), and figuring the softer springs would allow softer shock settings, I went down another two clicks to 7. I expected this to have noticeable understeer but it didn't. I liked it better and thought I might like softer springs all around but until I got them, I would experiment with what I had.
The next iteration was to raise the rear spring perches another .6" (which should have put the rear ride height at about where it was before I changed the springs - I didn't measure it though) and check the camber. In spite of the fact that I hadn't fooled with it since the shop aligned the car, the camber was messed up. I set the camber to about -1.4°. It was a good improvement but occasionally, at about 80 mph, it would feel as though the car was being pushed around as though in a strong wind. Otherwise, it was pretty stable most places with a bit less of the feeling that the rear wants to swing around in a hard turn.
A couple of takeaways - first, writing this makes me realize that I'm really not attacking this in a very organized manner. For example, I should re-measure the important things before each test such as alignment. Second, I wasn't surprised that a 30# difference in the rear springs made a substantial difference but I was surprised that the balance (at least as I could feel it - and I wouldn't argue that my but is less sensitive than when I was young but then it might never have been very sensitive!) was not more screwed up. I know have F:250#/R:100# springs. I think Certified Lotus said that Dave Bean sold fast road springs that were F150#/R:115#. I'm anxious to try that. Third, it's interesting how there are such a wide range of setups depending on how people like it and I suspect how they drive. Driving around town with F:250#/R:130# was never a problem. It was firm but not jarring. With the shocks stiffened, it was pretty stable on the highway but I didn't feel it was neutral enough for my taste. I know others like that setup pretty well. I think I gave it a good chance of working. I had a very helpful conversation with JR73 awhile back and his rates seemed crazy to me. It expect he is a much better driver than I and that could be why he liked his setup. We're all different!
-
Thanks, Tom! I'm thinking mine are a bit more modern because when I got past 14 clicks, the 15th felt like the 14th, 13th, 12th, etc. In fact I found a note I made where I went to the 16th click. Also, I think I got mine in '90s. I took a closer look at my rear shocks and saw a number stamped on the shock so I thought I might call the SPAX folks and see if that number meant anything to them.
-
I know have F:250#/R:100# springs. I think Certified Lotus said that Dave Bean sold fast road springs that were F150#/R:115#. I'm anxious to try that.
If you think you have oversteer with a 250 f / 130 r, you will definitely have oversteer softening the front that much. Are you testing oversteer limit on the street or track/autocross?
-
Well, that is a thought. I assume that Dave Bean or somebody there who knew has ass from a hole on a ground devised their suggested rates (F:150#/R:115#). It seems reasonable since they are both a similar multiple from the stock rates which I know to work pretty well. Of course my original rates (F:250#/R:130#) are also similar multiples of the stock rates and I wasn't able to get comfortable with them. I wish I had a lot more springs to try!
I haven't tried any autocrosses (I'm not sure I could get a helmet on but I ought to give it a try). I have a look I drive that has some S-type series of corners, a long sort of a sweeper on to a highway, some straight highway, and a rater tight exit off the highway. I think it can tell me what I want to know but there is traffic to deal with so it's not ideal.
-
BDA. I was looking online and there are a number of articles talking about low profile tires making their cars twitchy to drive. That is, every bump tends to steer the car. Is that what you are talking about? Some claim they grip better but are more difficult to drive on the street.
Do you still have your old standard size wheels and tires to try?
-
I don't think that's it, Pfreen. After I posted that I found one of my front hub's bearings were a little loose. I suspect that was my problem. If it drys up and I get a chance today, I'll see if that cured it.
-
Fingers crossed😊
-
This is a really old thread but I'm posting to it for a couple of reasons.
First, I want to warn anybody who might be using MY experiences up till now in this thread to help them sort out their handling that my experiences are not likely to be very useful since I had been dealing with bad shocks the entire time. This became obvious to me when I installed a set of Protech shocks. I expect that posted documents and other people's experience might be useful.
Second, since I am finally using good shocks, I'll be experimenting with them (and probably also spring changes) and someone may find my experiences useful.
To bring those who are interested/curious/not bored yet, let me bring you up to date. My TCS is running 250# front springs and 130# rear springs. I have only the stock front anti roll bar (~3/4"). A couple of posts ago, I mentioned that my front end bearings were a little loose. That's been fixed. I've been experimenting a bit with different shocks settings. Protech advised that I start with setting about 1/2 stiffness. There are 13 clicks of adjustment so I set them all to 7 clicks. The interesting thing to me is that they didn't ask me what my spring rates were! That felt pretty good but the rear felt like it wanted to swing out on sweepers. Twisty roads were no problem, in fact they were great! A twisty section that I could do at about 60 mph holding on for dear life was now fun! I haven't been able to get faster than 60 but that was because I chickened out. It was A LOT more stable. The other thing is that I felt the highway stability could be improved a bit.
Remembering that the Spax tech guy suggested making changes two clicks at a time until you needed fine adjustments, I stiffened the front and rear by two clicks - to nine clicks. I wouldn't call the ride rough but it was very bouncy. I think that was because I may not have hit any real bumps but I felt every undulation in the road. It was not very comfortable. It handled the twisty bits about the same and the highway stability was maybe a little better.
I went down to eight clicks in the front and seven in the rear. The twisty stuff was still about as good and the highway stability was pretty good but it still felt like it was trying to swap ends in the sweepers. It might have been a little better. (note: at one point I inadvertently set one rear to six clicks with the other at 7. This made for some odd highway feelings!)
That's where I am now. It handles twisty stuff and a pretty tight clover-leaf really well. It feels a little loose in a sweeper (my sweeper is an on ramp and I wonder if it might be a bit off camber...). Highway stability is pretty good. I would feel comfortable driving it under just about every condition I'm likely to have but I feel the highway stability could be improved. I don't believe this is alignment (see attached last alignment printout). For whatever reason I am "light" on the caster on the passenger side - maybe a bent upright? Maybe that might contribute to some instability. In any case, my memory was that when I was young and stupider and my car was new, on a road trip I drove 90 mph all day with little effort. Now driving 80 for a little while requires a little effort so I think there is some improvement to be had there.
-
0.9 is pretty darn close to 1.0 so I think your camber is fine on the LF.
The upright is bent for sure on the RF. I would fix that before changing anymore settings.
-
So you expect that caster differential to be noticeable... I have adjustable upper A-arms so that's why my camber is good.
-
If the objective is street driving, why not soften the fronts instead of hardening up the rear?
That should make it more comfortable and more forgiving as well.
If you can find a local track that has 'free practice' days, that would be brilliant (and usually cheap). I've taken advantage of a few of those - a lot better than doing this on an off ramp.
You can happily lose it (ahem, I mean find the limits) multiple times in quick succession and not hit anything (usually).
-
I’m really only interested in street driving. I’ve been associating highway instability or a wandering tendency with shocks that are too soft for their springs. Since I was feeling a little bit of that wandering sensation, I figured that I was at a bit of a floor on shock adjustment. But I will try some softer settings and see how they turn out.
There’s a track not too far from me. Last weekend, I was in a car show there in conjunction with a vintage race. They lead us car show participants on a few laps around the track - it was the first time I’d driven on a race track in over forty years! A lot of fun even with reduced speeds and no passing. I found I hit every apex way too early! I might look into a track day if I can find a helmet. Hopefully it will fit in the car with my additional headroom!
-
I would do an autocross before a track day in a Europa. Much easier and safer to find the limit. Our SCCA region autocross even has free loaner helmets. FWIW, A shocks main purpose is to control the spring. On flat ground, you can have dead or really soft shocks. I think your instability is the 1.5* caster. A degree from side to side is one thing but 1.5* total isn't much. If you've ever driven a car in reverse fast, it doesn't take much to get out of control as the caster is negative. You need caster for stability.
-
It’s been even longer since I’ve autocrossed than racing but that was something I was considering as a less expensive, more available, and safer option for testing.
You’re confirming JB’s recommendation so taking care of that will be my priority.
Thanks, everyone, for your comments. I’ll report back when I get my caster squared away.
-
Ive been following this thread with huge interest and would like to add my (unscientific) experiences to the mix. I ran Spax back in the nineties with mixed results, i could never get the car to feel good ie. a car you have absolute confidence in at any speed. I ran Avon CR38's then Yokohama AO32R's which were slightly better but still not right. It wasnt until I went to AVO shox and a twinlink with my current tire of choice Toyo R888R's at low pressures 16/26 that the car felt really good. Predictable and excellent grip with a small amount of understeer as default with oversteer easily provoked by throttle input. I run 7 clicks front and 5 rear on standard Geo settings.
Yes it still needs caution at high speed bends when lifting off as JB says...Small price to pay for the agility on cross country roads I think.
The biggest surprise to me was how low the tyre pressures needed to go to dial out any front end twitchyness. I was lucky as a friend here in the UK runs a TC with these tyres and recommended trying lower presures, previously 30/20 and it was twitchy!
As I said unscientific but the car handles the best it has ever done and perfectly stable at speeds over 100MPH.
Sadly the tyres dont appear to last long on the rears!
-
Thanks for your experience. When I get my caster sorted out, I’ll consider more experiments with tire pressure.
Europas normally eat rear tires. When mine was new, the rears didn’t last much over 10,000 miles while the fronts seemed to last forever!
-
Spinning lots of donuts in parking lots? I have 15k on mine and it’s like there is no wear at all.
-
Thank you very much for resurrecting this thread….it’s a fascinating subject and I have been interested in adjusting my suspension to see what the results would be. I'll measure where I am now and slowly make recorded adjustments.
From memory I seem to remember that if you have an oversteering car you soften the rear or harden the front….and vice versa
Makes it sound easy….clearly there are so many subtleties like caster toe in and out that need to be addressed….and this thread will be a useful resource…..thanks
-
Spinning lots of donuts in parking lots? I have 15k on mine and it%u2019s like there is no wear at all.
That's interesting, JB. When my current Europa was new, my rear tires lasted about 10,000 miles. I owned another Europa previous to this one and I believe I had a similar experience with it but that is really stretching my memory. My foggy memory is that it was accepted as normal by those at the Lotus distributor where I bought my current car. I had also heard that cars came from the factory sometimes had very excessive rear toe in (that MIGHT have been recounted by somebody at the distributor). I did not ever get confirmation of that.
My impression about rear tire wear is driven by my memory of long ago. If the rumor about the rear toe from the factory is true, that might be the reason for the short tire wear and paying attention to your toe in would be the solution. I seem to remember hearing more recently that rear tire wear was a problem for other mid-engined cars like Ferraris.
I had to replace my rear tires a few years ago with less than 10,000 miles. It's possible that I had too much rear toe in then.
This brings me something I remember you posted about setting rear toe in. I made a note that you said that 0.060" washers on both sides would change the total toe in by 20'. Did I get that right?
-
Thank you very much for resurrecting this thread….it’s a fascinating subject and I have been interested in adjusting my suspension to see what the results would be. I'll measure where I am now and slowly make recorded adjustments.
From memory I seem to remember that if you have an oversteering car you soften the rear or harden the front….and vice versa
Makes it sound easy….clearly there are so many subtleties like caster toe in and out that need to be addressed….and this thread will be a useful resource…..thanks
That's right. Increasing the roll resistance at the rear will tend to increase oversteer. You can increase the roll resistance with an antiroll bar, stiffer springs, or stiffer shocks. I found this article that might be helpful (https://nasaspeed.news/tech/suspension/damper-tuning/). I think a shock change would be less quantifiable than changing springs or rear anti roll bar. As you suggest, it is a balance. Less stiffness in the front will change the balance in the same way. And as you also noted, caster, camber, and toe in also play a role. I would also add that ride height does too. Lowering your car may but may not enhance your handling. The benefit of lowering of the center of gravity may be overridden by a poorer camber change curve.
Keep in mind that I am a rank amateur at this so verifying anything I say that seems odd would be advisable and hopefully if I'm wrong about something somebody will correct me. :)
-
Thanks BDA, good article
-
Spinning lots of donuts in parking lots? I have 15k on mine and it’s like there is no wear at all.
Haha....You got me!
Seriously though the Toyo R888r's are semi slick track tires and even on the road wont get much more than 2000 miles on the rears especially if driven enthusiastically. I may have to find an alternative or have a set just for track days.
-
Ah, slicks. The equivalent of the vibrator in the sexual world: amazing performance but addictive and needs constant charging/changing ;-)
-
Ah, slicks. The equivalent of the vibrator in the sexual world: amazing performance but addictive and needs constant charging/changing ;-)
:FUNNY: best analogy of slicks i've ever heard ;D
-
I like this thread as it has alot of info. Just thought I would add my latest experience with my TCS. I have gone through a few iterations of spring/shocks. I have a great situation, in that I have access to a private track that has many tight turns (L&R) and allows one to find the limits of a car very fast. There is no way to duplicate this on the road.
My car came with the usual "fast road" set up that the normal vendors seem to offer - the 250lb front springs and stock rear springs. Then I moved to rear uprated around 130lbs. I was on 15" 50 series tires. It was hard to tell on the road, but on the track this was horrible. Actually a bit dangerous. I even called Banks and asked for advice. He said get rid of the low profile tires. So, those went and I moved to 60 series 13". Still horrible.
I next moved back to stock springs with Konis that PFreen gave me. Very happy, but a bit slow around the track.
I called Barry Spencer to see what he recommended and he sent me 160lb front and 120 lb rear. Tire pressure is 17f / 23r for track on Toyo R888R. This is spectacular. I also just did a day at Watkins Glen and was worried that I was a bit soft for that track, but it exceeded expectations.
So, there is my set up for now.
-
I don't know if I've said this already but the initial reason for this thread was that my car handled horribly. Going 90 mph was a white knuckle experience. It felt that if I moved the steering wheel a quarter of an inch, I would be in the ditch on the side of the highway. Uneven or bumpy pavement was freighting. It felt like I could be thrown into the next lane on either side without warning.
I tried alignments and different springs (softer springs were marginally better). I changed everything else but I hadn't changed the shocks. I ordered some Protech shocks which are much too pretty to put under a car. I believe there is a thread somewhere of my experience with Protech but in case you're not motivated to find it, the stiffness of all the shocks were not the same side to side. Protech made it right for me and gave me shock diyno sheets on them. It turned out that the Spax were completely worn out (they weren't old in miles but in years. With the Protech shocks, I had a different car. It was a blast and much more stable than it was! I would pay more attention to the "data" and experiences offered by posters in this thread rather than my experimenting.
Recently, I swapped out my 250/130 springs for 160/115. They are certainly a bit less tiring on trips and handle great but at the same time, I don't want to pooh pooh the stiffer springs because they were not as harsh as one would expect. The only problem with the springs I have not is that I have all the spring perches screwed all the way down and the car is still a bit higher than I'd prefer. My front springs are 10" and the rear are 14" long. If I do change them, I'd got to 8" 160# or 150# and 12" 115# springs.
The idea for 150/115 came from CertifiedLotus (see and index of his build here: https://www.lotuseuropa.org/LotusForum/index.php?topic=4871.0). I got my springs from Dave Bean and they didn't have 150s so I settled for 160. He loved them. I like them too.
-
I like this thread as it has alot of info. Just thought I would add my latest experience with my TCS. I have gone through a few iterations of spring/shocks. I have a great situation, in that I have access to a private track that has many tight turns (L&R) and allows one to find the limits of a car very fast. There is no way to duplicate this on the road.
My car came with the usual "fast road" set up that the normal vendors seem to offer - the 250lb front springs and stock rear springs. Then I moved to rear uprated around 130lbs. I was on 15" 50 series tires. It was hard to tell on the road, but on the track this was horrible. Actually a bit dangerous. I even called Banks and asked for advice. He said get rid of the low profile tires. So, those went and I moved to 60 series 13". Still horrible.
I next moved back to stock springs with Konis that PFreen gave me. Very happy, but a bit slow around the track.
I called Barry Spencer to see what he recommended and he sent me 160lb front and 120 lb rear. Tire pressure is 17f / 23r for track on Toyo R888R. This is spectacular. I also just did a day at Watkins Glen and was worried that I was a bit soft for that track, but it exceeded expectations.
So, there is my set up for now.
You should try the stiffer springs with the R888R's. The better the tire, the stiffer you will need to be to limit the extra roll and camber loss from the tires.
FWIW, I started with 250 F then 350 F, now 400 F with a 7/8" bar soon, 3/4" hollow. I won't know if the 400's will balance it better until fall season starts. With 1* front camber and more caster than a Europa can have, I still murder the outer edge with 24 psi. Next outing will be 26 psi.
-
Clifton - As I get faster with the car, I will keep moving stiffer. What rear are you using with the 400#?
-
Clifton - As I get faster with the car, I will keep moving stiffer. What rear are you using with the 400#?
I'm running 450's in the rear. My rear is a lot different. I have a 40/60 weight dist and my rear suspension is a custom SLA and without looking, I think the motion ratio is around .65. I don't know how that compares to a stock Europa. I know Europa's run pretty soft rear springs compared to the front so I think the rear ratio or the roll center is higher to run such a soft spring. You wouldn't like a 450 in the rear, it would spin like a top. My front is the same though.
-
I have 250# front springs and 115# rear springs. I also have a 3/4" front sway bar and a 3/4" rear sway bar. I set ride height to the level I thought looked good. I have 175/70-13 front and 185/70-13 in the rear. I have not track tested.
When I first installed the 250# springs and protech shocks, the car would way oversteer. Scary. If you let off the gas in a corner, it wanted to spin.
I installed spring links on the rear sway bar to reduce the rear roll stiffness and oversteer. This is a way to moderate a sway bar. Another method would be to adjust the sway bar lever arm length.
Anyway, the rear sway bar spring link made the handling neutral.
The handling characteristics are determined by tires, setup (camber, toe, etc) and front and rear spring/damper combinations. There are a number of other contributing factors too numerous to list. Put together, it is the difference between winning and losing for every race car and it takes a lot of experimenting. Even specific to the track.
I am sure in my case, if I put the Toyo tires on, I would have to retune the handling.
So, I guess there is no optimum for all Lotus Europas and drivers. However, these posts are very interesting.