has anyone played with suspension settings and tire pressures. would appreciate your observations and thoughts. thanks.

 

I have a bit. The way the car comes from the factory, is the same setup they used a the 'Ring. That being said, the 'Ring is a big, long track with lots of straightaways so the suspension is tuned for that type of driving. Recently I had the car on Streets of Willow, which is a much smaller, shorter technical track. After my first session, tire pressures were at 55, and I immediatly dropped them to 35 F and 38 R. It made a big difference, but the car still showed its weight in the tighter corners. I did not play with the suspension, but lowering it and adding some compression and rebound would have helped enormously. However, this would have killed the cars level of comfort and roadgoing ability on the street - so, I didn't do it. If you haven't done so, read the manual. There is an entire section dedicated to adjusting the suspension. The tools required to do it are in the trunk. Pretty cool if you ask me.
The one thing I plan on doing for the street is increasing the rebound. It's a bit soft for my taste and I feel on some big dips the car tends to float after the first stage of compression. Other than that, there really is no end to how well you can tune this cars suspension. Hope that helps.

 

Did you keep times at the street? Best I could muster in the very non stock C32 was a 1:32 but that was before the LSD and Bars. That track is all about chassis ability and not power so wonder how the BS did there.

Have you been to the big track? The BS would likely just eat the ground between 6 and 9 like a monster.

What groups to you track with? Would love to come out for a ride next time you go out.

 

Also how did the corsa's hold up? They are a finiky tire if the chassis is not set well and they are very touchy to pressures as well.

When you went to 55 psi what was your "cold" starting point? I know I always have to bleed out air and by the end of the day the cold tire pressures are in the high 20's.

I was shocked to see that MB put the psi ratings for the BS as a reverse stagger . That is what I have always run on a C32.

 

LZH
Corsa's gained a reputation of chunking, any indication of that. Secondly, were the 35/38 psi a wild guess or did you work down to those pressures.
I'm tracking my car next week and appreciate your input.
Jimmy

 

Cyn & Jim - Yes, I did (keep times). 1:30 on the big track, and 1:18 on streets running the back bowl config. I run business development for a Grand Am race team and we had both tracks doing testing on one of our DP cars.
I wasn't really planning on doing much track time, so I didn't take tire temps before my first session. Then as soon as I got out there it was all over, and I realized I needed to come in and make a few adjustments if I really wanted to push it. So, needless to say, I was shocked when I saw 55psi and immediately backed it off to where I thought it should be. It made a big difference. But to be perfectly honest, and this was discussed in my track thread previously, the temps combined with the altitude were brutal that day. I was standing on it exiting turns with very little to no wheel spin. If I had done that tonight, temp is 60, in 1st or 2nd, the thing would have been WAY sideways. So, on a cold winter morning at willow, I think I could have shaved at least 2-3 seconds off...maybe more if I wanted to be stupid. But I really like this car and dropping a wheel at willow would be ugly...
The corsa's are.....ok. They performed very very well on the track, but as Jim stated, they chunked quite a bit and since both tracks at willow kill the front left - my car now steers a bit right. My corsa's are fine for the street after all that, but I wouldn't run them much more on the track. I think I'll be putting some MPSC's on as soon as these are gone. And that wont be long...
Jim - I had some pretty good race guys with me ( the crew) and they suggested going straight to 35/38. It made a big difference and the car really just grabbed, hunkered down and ate the big track up. Because of the weight, it had a harder time on streets. As Cyn correctly suggested, the car was a friggin monster from 6-9 on the big track. I was exiting 9 at about 120 to give you and idea of how much speed it will carry. But, and this is a big but....you really have to push it through 7 and 8 and be on the power, no lifting whatsoever. I did lift through there once with the track control on and it saved my ***. I did this simply to see how aggressive the black series ESP is written and how well it could save a novice driver. It worked well to say the least.
Enjoy your cars guys, and Jim, have fun out there and be safe. I'll be interested to hear your impressions next week.

 

LZH,
Thank you for the input on tire pressures. 1:30 !!!. For those on the board not familiar with Big Willow, that is serious fast for a street car. I don't think any of the glossy fish wraps got close to that number in a Ford GT or Z06.

One last question, does the car need a wing (more down force0 in turn 8?

 

A well driven Z-06 runs a 1:30-1:31 at the big track with stock tires and in the high 1:20's on Hoosiers.

But that car is 800 pound lighter remember.

A 1:30 is insane for that CLK I never thought it would be that quick.

 

Thx guys !! Honestly Jim, the car felt very well planted through 7, 8 and 9. As long as you stay in the throttle though. The second you lift through there (assuming you're carrying some good speed) the rear end gets loose. The CLK BS just has so much excellent mechanical grip, as long as you use it properly and keep your foot in it. The other thing that really, really impressed me is the rear end. Coming into 1 and standing on the brakes, most other cars would get real tail happy. You can feel the rear dif working to put the traction down under heavy braking and the tail just stays straight as an arrow and grips like nothing you've ever seen in a road car. I was very impressed with its manners on the track. Man, now you got me wanting to get it back out there !!!!!

 

So you are saying you ran a 1:18 running the whole Streets track. By the whole track I mean you ran the bowl, the skid pad and none of the cut offs? That time is faster than almost any race car. A SCCA 3-series race car and Champion Audi S4 run low to mid 1:20's and the BS is 4-8 seconds faster?

 

That was only the third time I've run streets and I'm not very familiar with the various configurations. There were no cut offs around the back but I was running the back bowl and skidpad. There was also a heavily modded EVO out there that day with slicks and he was running 1:15's all day

 

That must not be the whole track as a galardo runs a 1:34 on the Street (whole course) and I swear the track record is around the high 1:1x.xx. Either that or this BS CLK is faster than most race cars!

The time at the big track is much more understandable. I run a 1:34 in a C32 with many mods so low 1:30's for the CLK BS makes sense. A well driven lotus elise is a 1:31 second car at the big track and a Z-06 also is in that company.

Anything in the low 1:30's is amazing for a street car weighing in at 3800 pounds without a driver in the car.

 

Beginners luck I guess

 

OK, with the help of the suspension engineer at KW, we made some changes at the track. First of all, unlike the adjustable suspension I've run in the past, this one is much easier to feel the difference. With Koni, you never knew exactly how many clicks would result in a difference in feel, and the same with the PSS 9 Bilsteins.

These were easy. One click in front elimated my looseness in rear braking. The KW has so much more adjustability then just about anything out there.
I believe you get twice as much range as the PSS 9s.

Jimmy

 

Jim please let us know what you ended up at for the compression and camber front and rear. Toe as well if you changed that too. Thanks. Sean