Suspension tune and handling journey

[BDA]

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. 

[S2Zetec54]

Thanks BDA, good article

[europa88]

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.

[jbcollier]

Ah, slicks.  The equivalent of the vibrator in the sexual world: amazing performance but addictive and needs constant charging/changing ;-)

[europa88]

Ah, slicks.  The equivalent of the vibrator in the sexual world: amazing performance but addictive and needs constant charging/changing ;-)

best analogy of slicks i've ever heard 

[cazman]

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.

[BDA]

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.

[Clifton]

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.

[cazman]

Clifton - As I get faster with the car, I will keep moving stiffer. What rear are you using with the 400#?

[Clifton]

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.

[Pfreen]

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.