Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: LotusJoe on Monday,June 24, 2013, 04:37:10 PM
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(http://www.lotuseuropa.org/gallery/albums/album13/TCSpecialUprights.jpg)
If you were making new uprights would you change the bearing landing to accommodate a different type of bearing?
Maybe leave the material inside the upright so you don't need the bearing spacer any longer?
(http://www.lotuseuropa.org/gallery/albums/album13/Bearing_spacer.jpg)
Or maybe make an upright that would fit the S-2, Twin Cam and the Special, if that is possible. :confused:
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I'm guessing you're all about to start designing & fabricating then Joe ? Well, as you asked, here's my (possibly controversial ?) 2c worth.
Yep, I'd certainly change the bearings. Despite the theories stated about low loading and the way some folks claim the bearings last well, that's not been my experience. When I used my car daily it wasn't unusual for me to have to change the rear bearings at 2yrs because I had an MoT garage that was very strict about wheel play and any play would get a fail on the annual test.
So, in an ideal world with machine shop facilities my first step would be to fit a modern and better sealed design of bearing, which would probably mean a complete new casting. My first thoughts would be to try to use something like Lotus have used on the Elise, which is a double row taper roller bearing. (picture attached) That would do away with the spacer as well, but be aware that the Elise has an entirely different design of rear suspension using CV joints and twin links.
The steel spacer is an interesting one. I can see why it's present in the OEM design, but given how Chapman was ever trying to lose weight (and costs) it did make me wonder why he didn't do away with it and rely on an internal shoulder in the housing to support the bearings. I can only think that he decided it wasn't strong enough or perhaps might wear in service, making the infamous "hub falling off" sequence a bit more likely ?
Finally, why not incorporate a small lug on the top of the bearing carrier itself to allow an optional upper link to be added ? There's quite a few folks with twin link suspensions these days and it might increase the potential market for any future production run ? I would have thought that as long as the critical external/suspension dimensions are the same for S2 & TC's then anything you design should be applicable to both markets.
Brian
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Very interesting question, Joe, and Brian has some equally interesting suggestions. A bit of thought would be required on my part if I were to suggest a significant design change. I have yet to change my rear bearings ( a job I'll likely be tackling next year) so I have yet to get intimate with that part of the car, at which point I would probably have thought out some ideas (... why the hell did they do it that way? It would have been much better if they did it this way...).
Anyway, right off the top of my head, I think the current design could be improved if it were altered to include a steel sleeve in the bearing bore. This would require more material around the exterior portion of the housing to maintain a suitable robust assembly. An aluminum bearing housing is always a bad idea in a long term assembly. The steel suffers wear & tear much better, is more dimensionally stable, is easier to install bearings (allows better 'feel'), and, when worse comes to worse, a steel sleeve can be replaced. Comments and critisims on this idea accepted.
That's one quick though for the moment. If anything else comes to mind I'll post it. I'm sure discussion will ensue.
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The inside of the upright is hollow as I'm sure most of you know. I suspect this was a product of the casting process. My thought would be to leave the upright solid with a hole slightly bigger than the stub axle to eliminate the need for the steel spacer. Taking Trevor's idea a step further, maybe pressing in a steel spacer on the inner bore and a steel sleeve for the outer bore. This would make the landing for the back side of the bearings larger and help eliminate movement in the upright. I also like the addition of the circlips. An update on the bearings I think would be in order. I'm not an expert on what that would be, so more research is needed. I am thinking of having them made in 6061 aluminum which would be far superior to the aluminum cast. Being able to accommodate all the models would help eliminate the need for multiple designs. But it would have to be done in such a way that didn't require a bunch of additional modifications to any of the ancillary parts. It looks to me that the main difference, aside from the bearings is the attachment of the lower link. The S-2s lower link looks to be offset so it can attach to the upright on the same side as the shock, where the TC Special is straight and attaches to the opposite side. That may be a simple as boring both attachment holes. I haven't measured the different uprights so I'm not sure if it is that simple.
(http://www.lotuseuropa.org/gallery/albums/album13/S_2_Upright.jpg) (http://www.lotuseuropa.org/gallery/albums/album13/Upright_TCSpecial.jpg)
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I think your interpretation of the lower link/damper assembly is right, the casting looks (from pictures at least) to be able to work with both designs.
A solid casting would be quite a bit heavier and might raise another problem with the potential for shrinkage cavities inside the section; there are lots of ways to combat this and of course you can make much thicker Al castings, but it will complicate the casting procedure. So maybe there might have been good reasons for having a hollow casting ?
But you could still have a thicker bearing section with a built-in spacer and personally I think it's very possible to come up with a design to appeal to the S2 & TC owners. The snag in my mind is exactly what loads you get from having the driveshaft as the upper link, if it wasn't there it would be much easier. The Elise for instance uses a thick Aluminium extrusion as a carrier - yep, they just squirt out a length of extrusion and slice it up into hub carriers ! ( ok, maybe it's not quite that simple.... ;) )
Brian
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Brian mentions weight, and I think this is an important consideration. As Lotus owners, the weight of any component or mod is always on the mind, sometimes to a ridiculous degree. However, this is unsprung weight, and its effect on a very light weight car can be significant.
Just food for thought...
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The inside of the upright is hollow as I'm sure most of you know. I suspect this was a product of the casting process. My thought would be to leave the upright solid with a hole slightly bigger than the stub axle to eliminate the need for the steel spacer.
I'm afraid this would not work since the bearing inner races would then jam on the upright and lock the stub axle to the upright. Remember that the original design locks the stub axle, the inner bearings inner race, the steel spacer, the outer bearings inner race and the hub flange firmly together. And then the outer bearings outer race is held in place in the upright by the square plate on the front link arm. While the inner bearings outer race is free to float in the upright and letting the balls roll freely in both bearings. I don't have the link ready, but the workshop manual has a very clear drawing of this.
But I really like the ideas you posted of steel inserts for the bearings or the idea of using some better material than originally. I have a Special, and had no problems sourcing the bearings, so making a uniform upright with these bearings would be an improvement for S1-2 and TC. I don't know enough about bearings to come up with yet another type that would beat the Special's configuration.
As I see the original design, it looks like someone took the smallest possible diameter to hold the bearings and then added the 'ears' for the front link arm and the 'hanging part' for the lower link. In my view a new upright might as well be square on the outside from the start, and maybe the part for the lower link could be a second part that attaches to the center part. And the part for an optional upper link could as well.
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I think in the case of the internal material of the upright we're not talking about much weight. When I was having some casting of Aluminum done the foundry was happy to cast my project in solid aluminum. However the guy actually doing the casting said "Hey you should put a plug in the center so you don't use so much Aluminum; cause you know we charge by the pound. I can cast this at half the weight...but it's your money." I'm thinking it was a cost savings for production purposes and not necessarily weight savings on the car. Even today extrusions and castings are still popular due to the savings in cost. Also CNC technology didn't exist at that time.
I'm not suggesting that lighter isn't better. But I would be willing to give up a bit of weight for a superior carrier with updated bearings that wouldn't fail. I will know better about how much material we are talking about after the parts are scanned. I would be willing to guess that it is less than 1 pound.
(http://www.lotuseuropa.org/gallery/albums/album13/CutAwayRearHub.jpg) (http://www.lotuseuropa.org/gallery/albums/album13/Hub_Carrier.jpg)
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The inside of the upright is hollow as I'm sure most of you know. I suspect this was a product of the casting process. My thought would be to leave the upright solid with a hole slightly bigger than the stub axle to eliminate the need for the steel spacer.
I'm afraid this would not work since the bearing inner races would then jam on the upright and lock the stub axle to the upright. Remember that the original design locks the stub axle, the inner bearings inner race, the steel spacer, the outer bearings inner race and the hub flange firmly together. And then the outer bearings outer race is held in place in the upright by the square plate on the front link arm. While the inner bearings outer race is free to float in the upright and letting the balls roll freely in both bearings. I don't have the link ready, but the workshop manual has a very clear drawing of this.
I found the drawings and put them in my previous post. I get what your saying...More thinking required :confused:
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I got a pair of uprights from one of our members (Joji AKA Grumblebuns) they were however still assembled in the trailing arms. But with a little persuasion I was able to get them apart and cleaned up good enough to scan. More progress next week. If anyone is looking a set of slightly bent trailing arms he might want to sell them. ;D
(http://www.lotuseuropa.org/gallery/albums/album13/Trailing_arms_001.sized.jpg)
(http://www.lotuseuropa.org/gallery/albums/album13/Joji_TCSpecial_uprights.jpg)
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I keep thinking about your question on the uprights. Yes part is hollow, so how much would it weigh if it were solid vs. the current design?
Take a mid eighties 911 rear set up. That stinkin' thing weighs a ton per side. So, then we enter un-sprung weight.........since it has a direct correlation with spings/shock........is it really going to make that much difference?
I ask because I don't know.
I get all dreamy thinking of uprights being milled on a C&C machine with the cutting water/oil and flying aluminum bits.........
oooooo'
Or....fad em' up out of steel plate, hollow and strong.
mike
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I thinking about solid 6061 Aluminum. I filled the void with water and it was just over a cup. So if you do the conversion it should be somewhere around 1.4 lbs of additional weight per upright. Too much? :confused:
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Soooo, just over one pound? I must be missing something cuz that doesn't sound like a big deal to me. If it was a big deal, get springs that have a bit more juice.
I wonder if the original design with the hollow area was more about saving money than weight.........hmmm.......
mike
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(part quote)
I wonder if the original design with the hollow area was more about saving money then weight.........hmmm.......
mike
Could well be Mike, although (allegedly) Chapman bawled out one of his mechanics for putting washers underneath the bolts on one of his cars with the phrase "why are you taking those washers for a ride on my car ?" :)
But casting thicker sections can give you problems with shrinkage cavities as the outer skin solidifies leaving the inner core molten. Then as that finally solidifies it contracts and you get cavities forming. That's not an issue here because it's hollow anyway, but the snag is you might get a defect in an area you want to machine or use.
The old way to prevent this was to either insulate/electrical trace heat the mold and have very slow cooling times, or "feed" the centre with new molten metal so you'd end up with the shrinkage taking place above the parts you needed. There's probably other ways of doing the job, but the main thing was that it extended the production times on a part, so it would cost more to make. Not a big deal with low production runs, but Lotus were making thousands of these things so it would add pennies.
On the other hand, a simpler casting using less metal, would be cheaper on both counts - production & payment per pound. So you could well be on the money with the cost ! ;)
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Completed the Upright scan today!
(http://www.lotuseuropa.org/gallery/albums/album13/bearing_carrier.png)
I also weighed the stock carrier and it is 2.4 lbs.
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Isn't technology amazing............
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Completed the Upright scan today!
(http://www.lotuseuropa.org/gallery/albums/album13/bearing_carrier.png)
I also weighed the stock carrier and it is 2.4 lbs.
Hi
Now I'm picking up an old topic!
Do you possibly have a step or sat file on those uprights. I'm going to rebuild the suspension, and a 3D model would be great to have. :D
Hans
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Carlsson, it looks like you've settled on making a new casting. Another member did just that but I don't think he gave any details about his except that his was solid. Have you thought about fabricating rear uprights?
I visited a race team that was the factory Oldsmobile effort in IMSA many years ago. While the car wasn't successful, it was very advanced with a lot of honeycomb, etc. One thing I noticed is that the uprights were fabricated. I also remember from my racing days that my Lola had a fabricated rear cross member and my buddy's March Formula Atlantic car's similar cast cross member weighed about the same and mine was certainly cheaper.
Just a thought.
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FWIW, my uprights have 'cracked' around the mounting ears, and would need some added material (welded?) before I'd be happy with them. I got a quote of having them copied in steel - pic attached. Since then, thinking about it, seems maybe upgrading the bearings would be good, and as I'm intending to make the Miata disk brake conversion, so thinking of having the caliper mount incorporated into the hub.
The fab shop has many capabilities - a lathe with a 5' swing(old school, but very impressive!)- cnc, etc. Web site too. The price for one set a bit prohibitive, but for ten, not so bad...
PS - Brian - thanks for the Elise bearing/carrier diagram.
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I'm not a fabricator or machinist so I'm speaking from ignorance but the price for the steel version seems really expensive (if the aluminum version was cast, I can see where it would be pretty expensive. too bad we didn't get more information from the guy who had a new set cast from aluminum) but I suppose he's factoring in some engineering and drafting time as well as making a jig.
It would be interesting to know how much he'd charge for different quantities.
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Set-up and/or programming do add time/cost. The steel version quote uses DOM tube.
Would be interesting to see the cost difference between, say 10 sets of steel, and 10 sets of cast aluminum, or 6061 aluminum, after the machining is completed.
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Ouch, that looks expensive Andy. I don't know how recent the prices are but Spyder were quoting £195 (plus VAT) for their hub carriers - say £400/$550 ?
http://www.spydercars.co.uk/lotus-europa-series-2-spyder-double-wishbone-rear-suspension-and-driveshaft-conversion-r-s-c-2/ (http://www.spydercars.co.uk/lotus-europa-series-2-spyder-double-wishbone-rear-suspension-and-driveshaft-conversion-r-s-c-2/)
That's for the drum brake version but I can't see it costing much more to get a caliper mount added.
The price for 10 sets looks more attractive though. I expect the single cost is pricing in a learning curve to cover unforeseen problems which I suppose seems reasonable.
Brian
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Spyder's steel uprights are apparently for their double wishbone rear suspension. Does anybody know if they are usable with the standard Europa suspension?
I went over to Bank's website thinking Richard might have a fabricated rear upright. That seemed like something he would make, but it doesn't appear so. There are no pictures of or prices for the uprights he lists. But interestingly, he does list an A-arm rear suspension! It appears that it fits on his 47, 62, and TC frames. For S2s, he still offers his twin link rear suspension (but not TCs!). Maybe that was well known but if so, I must have been out to lunch! ;)
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Have you guys tried protolabs.com for fabricated parts? Fully automated CNC quote and machining process in a good variety of materials. Upload a CAD file and they quote on the spot. Tolerances are a bit sloppy, so you might treat the raw machined part like a casting, leaving extra material for bearing mounts and bolt hole to be cleaned up in a secondary operation.
Tom
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Spyder's steel uprights are apparently for their double wishbone rear suspension. Does anybody know if they are usable with the standard Europa suspension?
From the pictures I've seen, I suspect not in fact I'd be surprised if they'd even come close.
They looked similar to those Roddymac designed and made for an upper & lower link design and I'd say like Roddy's they are more complex than the OEM carrier. I was just surprised at Andy's quote and trying to get my head around why the OEM design would cost so much when a more complex carrier was apparently cheaper.
Perhaps Roddymac should set up a sideline business of "Kustom Carriers" :)
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Perhaps Roddymac should set up a sideline business of "Kustom Carriers" :)
I had that thought too, but I thought he deserved a warning first! :)
I can't help believing that a good fabricator couldn't make these without a lot of fuss. If there was some money in it, I might ask the guy who did the fabrication on my car.
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My ears are burning....
My uprights set me back roughly $250 CDN for laser cutting and machining (twice, one pre welding and once post welding). Looking at the Europa pieces, there is a bit more work involved with the bearing housing portion, but it shouldn't be too difficult to fabricate. I think the hardest part would be building some jigs/fixtures to do the welding and the machining.
It looks like there are few things I should start fabricating once my car is done: lower front wishbones, fabricated rear hub carriers, laser or waterjet cut OEM type steering wheels (if I could get my hands on one to measure), and other odds and ends.
Rod
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If you're looking for suggestions, you might include stub axle/hub arrangement to go with your rear uprights. You might also add a mounting bracket for calipers and upper link.
This is a list that might never stop! :)
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LOL put seats on that list too. So many not easily sourced parts but semi easy to replicate parts with some good fabrication skill.
If you wanted steel fabricated uprights I bet they wouldn't be hard to do. If you want them cast so they look like factory that is where the cost will go up.
Ross
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FYI r.d. enterprises sells a seat kit.
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I thought the estimate rather expensive too. The fab shop is close, the estimate was free, so just to get a idea, I dropped off the hub carriers. I have access to another set of hub carriers, so this may be something looked at "down the road". Unless someone gets a group effort to have some made.
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Here's a steel upright fabricated for a replica Ford GT40.
A Europa upright wouldn't be any more difficult, I reckon.
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GavinT,
Great work!
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Here's a steel upright fabricated for a replica Ford GT40.
A Europa upright wouldn't be any more difficult, I reckon.
Several years ago, Richard Mann commissioned Wayne Mitchell of Dogrings.com to cast and machine type 47 uprights. Enough people were interested enough to let the project proceed. This what Wayne produced. The last two pictures shows the size difference between the TCS hub carrier and the type 47.
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There is also a guy in the Netherlands who has had a lot of seats made, he is on the Europa facebook group.
You can also get Weerg.com to get a CNC quote online, really easy! 7075 Aluminium should be plenty strong!
Serge
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Several years ago, Richard Mann commissioned Wayne Mitchell of Dogrings.com to cast and machine type 47 uprights. Enough people were interested enough to let the project proceed. This what Wayne produced. The last two pictures shows the size difference between the TCS hub carrier and the type 47.
Yes . . and I don't know how many sets of 47 uprights were needed to make that project viable but there would (should?) be many more punters looking for Europa uprights.
However, when ever the idea of producing cast items is floated, the discussion invariably evolves into what might be accommodated.
Some people merely want to replace their S1/S2 uprights with minimal fuss . . and maybe there's the issue of at least the appearance of originality.
Others with a TCS will need the extra material for the larger inner bearing together with the different trailing arm bolt pattern.
Still others see the opportunity to add an ear for an upper link or extra mounting points for rear disk callipers. Of course, no standard spec is ever determined because everyone has their own idea of an upper link and everyone is using different callipers.
Thus, the project inevitably expand to at least three versions.
The well meaning person undertaking the project likely has one version in mind. For instance, an S1 owner may well not have access to a pair of TCS uprights and is therefor less confident of satisfying the TCS owner that the finished parts will fit correctly.
Likely also is the fact that in this day and age, the idea of one failure in service, and the potential liability issues flowing from that, would be reason enough for a private person to have second thoughts.
I'd guess it's a little different for a type 47 upright, too. While no one wants one of those to fail either, it's more likely that they're going to be race cars and as such, the idea of some perceived guarantee/warranty/liability doesn't loom so large.
Still and all, these on line CNC shops may be worthwhile investigating as they all seem to have a free quote option.
Is there a CAD file available and has anyone done this?
But if the quotes are higher than the cost of a TIG welder, well . . .
And of course, you'd be miffed if an axle broke anyway and dragged your nice new upright on the ground as your rear wheel sailed past and into the scenery. :(
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An in depth discussion on this topic is ongoing over on the yahoo group
Also, it was mentioned that Banks is reproducing them now.
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Carlsson, it looks like you've settled on making a new casting. Another member did just that but I don't think he gave any details about his except that his was solid. Have you thought about fabricating rear uprights?
I visited a race team that was the factory Oldsmobile effort in IMSA many years ago. While the car wasn't successful, it was very advanced with a lot of honeycomb, etc. One thing I noticed is that the uprights were fabricated. I also remember from my racing days that my Lola had a fabricated rear cross member and my buddy's March Formula Atlantic car's similar cast cross member weighed about the same and mine was certainly cheaper.
Just a thought.
No, I'm not going to make new uprights, but I'm considering mounting upper link arms. I've looked at a lotus that's rebuilt like this.
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Very interesting approach! I'd love to see it when it's done!
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Is this in addition to the stock radius arm?
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Is this in addition to the stock radius arm?
Yes, is it with the stock radius arm? Here are more pictures on a Swedish page.
https://rejsa.nu/forum/viewtopic.php?t=62945
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I didn't notice the inner attachments for the lower links. If the geometry is good, that's a better setup than stock or even Richard's twin link design because the position of the inner attachments don't move with movement in the engine/tranny.
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This topic reminded me that my machinist expressed an interest in developing a rear upright that will be an improvement to the stock one. I dropped off a few rear bearing housings/uprights, both for a S2 and a TCS for him to examine along with a rear stub axle for the S2. His initial comments were to beef up the flange area where the upright bolts to the trailing arm. The second was to go to a common bearing size for both inner and outer bearings. His other suggestion was to upgrade the stub axle with better material and a larger diameter. He also wants to make the upright the same for both the S2 and the TC/TCS. With different bolt patterns between the S2/TC and TCS, he may have to drill and tap eight holes (16) per upright to accommodate this if it's even possible.
Next time I talk with my machinist, I'll discuss the possibility of accommodating a way to add a rear disc setup in case someone wants to go that route. My goal is to get the cost down to about $1500/side or lower. This will include the bearing housing, stub axle and nut, spacer (if used) and possibly the bearings. I'll be on the hook for the first prototype no matter how much it costs so once Wayne is ready to proceed, I'll have to decide whether to give him the go ahead or shelve the project due to cost. We shall see how this project develops.
One advantage of working with Wayne is that he's sympathetic to our cause and I suspect that he will give me a price break on his labor cost as he did with the high balance tube manifold he machined for me. I'll give updates periodically on the progress.
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That sounds like an interesting project! I'd like to see what you end up with, Joji.
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Cold nights and chasing links brought me to this old thread.
So it's a resurrection tonight.
Read the whole thing and disappointed it seems no one ever finished up an improved design.
I've also been reading up on substitute stub axles.
Leaving my S2 stock for now but if I run into any issues the Corvair axle and tapered bearings swap looks like the way to go since I prefer to keep the original type axles.
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Anyone have a scrap upright I may section for educational purposes?
Been playing around a little with lost foam casting and how to make repeatable patterns.