Suspension tune and handling journey

[Pfreen]

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? 

[BDA]

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.

[Pfreen]

Fingers crossed😊

[BDA]

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.

[jbcollier]

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.

[BDA]

So you expect that caster differential to be noticeable... I have adjustable upper A-arms so that's why my camber is good.

[GavinT]

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).

[BDA]

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!

[Clifton]

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.

[BDA]

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.

[europa88]

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!

[BDA]

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!

[jbcollier]

Spinning lots of donuts in parking lots?  I have 15k on mine and it’s like there is no wear at all.

[S2Zetec54]

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

[BDA]

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?