I decided to take a serious look at the suspension on the Black for the upcoming track day. For those who have lowered or replaced the springs with the H&R's listen up. For those with stock cars who don't care and only want to buy a Black to add to their outstanding car collection, stop reading.

First, the car looks killer with the lower ride height. If your front spoiler scrapes a steep drive way, I've got some bad news for you. Your cars too low for optium handling. I have this secret suspension guru who works on nothing but race cars that I helped get started in his shop ten years ago. I'm not telling who he is because he ONLY works on race cars. He agreed to do a set up on a door slammer if I promised I wouldn't refer any internet friends. Why? Sample phone call. Hey,suspension Guru,...ah, you set up Jimmy's car and I want the same thing... how much! Midas only charges $29.95 and I can get the H&R's off the internet for $150!...get the picture.

Ok, I thought that replacing my springs with stiffer units H&R would be beneficial for track use. I had lowered the car over 1/2". My last track day the car did feel better but I noticed when I hit a bump at high speeds the back would step out. Actually the springs were going to infinity as I was actually on the bump stops. That is the problem with severe lowering even with the KW's, is that you loosing shock travel and riding the bump stops. After measuring the spring compressiom and the drop along with the shock travel, it was decided to raise the front a 1/4" and lower the rear 1/4" and remove the yellow bump stop (you still have two more black bump stops) to increase shock travel but still have a lower ride height. My guy then corner ballanced the car. When I picked the car up in the first block I drove it, it seemed much smoother. Turn in was sharper and the back end which has a tendancy to hang out was more controlable. I couldn't wait for Saturday.

11/1/08 0700 hours: Willow Springs Raceway, the fastest track in the west.
The event was sold out. Given that my car lacks a cage, or roll bar I'm relegatedd to drop down from the red group to the blue. No matter, pleanty of competition. After the obligitory, drivers meeting we grid up. Lota Vipers, several Zo6's, Mustang, GT3's Trubos' and of course one AMG Black. About 30 cars in our run group. As we grid up, I notice some sprinkles of rain.
I look to the west and see dark clouds. The starter lines us up and just as we're about to take off, the starter tells us first two laps are under yellow.
I start off smartly, and I notice the rain is picking up. The rain is now pounding through my open window as I complete the first lap. I'm thinking maybe this will pass, as I enter turn three and the Mustang in front of me totally looses it in the wet. I complete the next lap and its raining harder then I see the lightning.

I was the the only run group that got out that day. The sky opened up and the track was red flaged.

I'll have a report on the suspension after my next track day on 11/13/08.

Jimmy

 

I'll just wait here.

 

Yea, me too...

 

Jim, give me the Cliffs Notes verison, you lost me! So what springs are you running? H&R or stock. When you say you raised the car 1/4 inch did you raise it with different springs or just the ride height on the coil-overs? I run the H&R's and I have tracked my car several times on high speed courses (Road America) and slower, smaller, tighter more technical courses and never experienced the rear "stepping out" on me (except on throttle, to be expected). I have had to make a lot of adjustments (mostly rebound) to get the feel "just right". I am by no means a suspension expert, but I would assume lower is better, why raise the car when you should be able to get the same results with the dampening adjustment? Better yet, I would opt for new coil-overs before raising the car up.

 

My car has the H&R springs and was very low in front. We raised it slightly about 1/4" (its still lower than stock) and it seems to have improved the rear end from stepping out as the the car hit the bump stops on high speed (120 + mph). This is a major issue at turn 8 at Willow Springs. Basicly, we loosened the car up with more shock travel and it seems to stick better.
I'll have an updated report after my track day on 11/13 when I can push it.
Jimmy

 

Ok, thanks, I understand what you are saying now, but I would think that raising the front would shift some additional weight bias to the rear which would further exagerate the rear end bottoming on the bump stops.

Keep us posted, intersting topic.

 

Jim,
You are correct we are shifting for more rear weight bias. So, we had to free up the rear as well. To do so we removed one of the bump stops so there is more rear shock travel. Suspension is a black art and what you think should help sometimes doesn't. Testing will tell.

On another topic, my buddy was at the track with his porsche twin turbo, and he has several hipo cars (F430, Z8, Ruf turbo cab, etc) I let him drive my Black and all he could say was these are the best seats I've ever sat in.
Then he drove it in the rain. Bottom line, he's buying one.
Jimmy

 

Jimmy - After you mentioned Willow, I suspected it was turn 8 that was giving you the problem. That bump coming down onto the apex can make things a bit interesting t 120+ mph. Nice job man, keep us posted. What mods did you have Evosport do ?

 

Evosport upgraded the ecu and installed H&R springs.

We found out that the high speed turns triggered an esp code that effectively put the car in limp mode. This could only be found out by track testing the car. This would never show up on a dyno. Credit Evosport
for finding out the cause that most other tuners haven't encountered becasue they haven't put their car on a road race course. It just so happens that it occurs in turn 8 at Willow where there is the most side loading and speed.

The bump in turn 8 causes the lowered cars not properly set up to hit the bump stops. This effectivily causes the spring to go to infinity bouncing the car to the left and causing your adrenaline to turn brown. We believe that with a little more shock travel and stiffer spring we can tune out the problem.
Jimmy

 

Come out on the 19th. I am going and would love to see a black series in action.

 

At willow I swear a softer suspension is equally as fast or faster than a very stiff now suspension. After driving a 335i stock and then lowered with TCKlyne coilovers (500 lb springs front and back) the lowered car was just 1 second quicker. The stock car just flows through 8 like a cloud while the lowered car would bounce and bottom through the corner. TC swore the car needed to be low but I had to raise the car up to make the suspension work correctly. Unless you use a 1000 lb spring a car will have suspension travel and it will bottom out if to low.

With a 4000 lb curb weight you have a lot of mass moving around and that mass will make all but the stiffest springs bottom out if set too low.

I agree with your post completely.

 

Funny, when I ran my car there a month after taking delivery I didn't have this problem at all - I would assume becaue of the stock ride height and springs. Granted, Turn 8 is one of the harder turns to master. Every time you go through there it's always a little different and you really have to just keep your foot planted and go for it. It does indeed require nerves of steel to keep your foot planted becasue lifting just the smallest bit can turn into a HUGE off.
Props to Evosport for figuring this out - I think I might take my car out for thier track day

 

A little confused ...

On the left side of page 213 in our Operators Manual, it says
clockwise equals harder and
counter-clockwise equals softer ...

Simple enough, however, on the right side of the same page (213) it states,
softer rebound> rotate compression stage clockwise
harder compression> rotate compression stage counter-clockwise

Question: Which way do I turn the rebound stage adjustment (F&R) to get a stiffer(harder) rebound setting ?

Or, when resetting to original setup, does turning both compression and rebound clockwise to the stop and before adjusting back out, is that full hard or soft?

Also, when adjusting ride height, I'd like to raise the car, measures at the wheel arch, about 1/4-3/8". How many turns on the spring adjusting ring would be needed?

*NOTE - I have a set of KW sport springs installed

Thanks

G

 

You are experiencing lost in translation. "If you have a harder compression stage" What they are saying... is... to optimize you must soften the setting. They are referring to tire and ride.

Harder is clockwise
Softer is counter-clockwise.

If you are confused go to the KW web site and they have diagrams which are much easier to follow.

Ride height since each car is different, your going to have to experiment. Just remember where you started with the adjustment ring.

 

Thanks Jim

I'm understanding you as ... turning the rebound adjustment clockwise will tighten (firm/slow) the rebound.

G

 

Yes. also see www.KW-suspension.com

 

Working the rear, I first turned it down (CW) all the way to the stop and backed it off 1 1/2 complete turns, per manual. Then I closed it down 3/4 turn ... was TOO stiff. I then backed it off (CCW) 1/4 turn and it feels perfect. For now I'm leaving the front as is ... I think it feels ok ... I may dial it down a 1/4 turn (CW) to see how it feels.

Thanks again

G

 

Glad it worked out. KW's are one of the easiest to adjust as you can feel the changes in one turn unlike a lot of the other adjustable shocks.