spr

OK for those of you with a c55 who have changed the stock suspension please chime in here. I cannot stand the poor handling of the car and grossundersteer. Yes I am coming from a 911 that I bassically turned into a track car but still, and yes I run lower pressure in the fron and more in the rear to try and dial some understeer out but it's no use. I have been through many driving schools and track events, so please don't go there either.

With that over, I want to change the suspension out. It appears that the options are these:

pss9's
ks coilovers in fixed and adjustable valving variants
AMG upgraded suspensoin from Germany
Kleemann springs and shocks
renntech springs??
Brabus?

Please let me know what you have and your impression v. the stock suspension

Also I am told that the camber is NOT adjustable, so how was this adjusted with the stock or upgraded suspension (front mainly) ????
If I could increase the camber in the front by at least -.5 degrees that would make a huge difference

Thanks guys.

Sean

RawAMGpower

I'm getting the pss9 next, so I'll know then. However, after I got the LSD installed the car did feel like it handled better. I can definitely corner faster now.

Fifth Ring

KW coilovers are very high quality, but I do not think they have shock-adjustable for the C-class. They also run very firm.

People have created negative camber using something called a K-mac fitting. Mixed reviews.

As someone who uses his C32 on tracks, I'd first invest in an LSD. But if you're also trying to improve the looks, I'd go with PSS9s.

rbaker

I agree, the handling sucks (relatively speaking). Heck, even my Mini Cooper S JCW handles better, and I wont talk about how much better my track prepped M3 handles! The C55 does stick, but turn in is horrible. Waaay nose heavy. Run wider tires, I suggest at least 235's up front. Any more and you might have to roll the fenders. I went for DOT-R's just to get enough stick. You could also change wheels or add spacers to widen the front track. I liked mine with 5mm spacers, but had too much trouble getting the wheel centered to avoid balance issues so I ditched them. I'm thinking of making custom ones but haven't had the motivation yet.

Add a washer to each of the lower strut to hub mounts for an extra -0.5 camber. It helps quite a bit... unfortunately, the particular bolt size & thread pitch that MB used are rather uncommon here & it's difficult to find a longer replacement, so I could only add 1 washer. I wish I could add another washer to each, but need longer bolts. If anyone has a source...

I would go slowly on the upgrades though, and not just ditch the whole factory setup. The car is plenty stiff enough, just needs an adjustment of weight transfer from end to end to balance it better. Oh, get rid of the silly 65-70lb battery from right over the front wheels, and put in a 24lb Hawker.

spr

First let me say that this is the response I am looking for. I would agree that it does stick once you sesitively load it and slowly at that. I did manage to run similiar speeds through my local canyons today surprisingly enough, and it didn't do as bad as I thought it would. I think the main problem is running a 225 on a 7.5" rim. I initially had that size front on the 911 and it was crappy. I did only run a 265 in the rear on a 10" rim but whatever. Upon upgrading to 02 hollow spokes with 8" fronts the difference was dramatic as was the unsprung weight's responsiveness etc. I think that with an 8" rim a 225 would be fine. I did also run an 8.5" rim with 225's and it tracked evily and had some bumpsteer but thank bbs for that garbage. Although it sounds a bit hokey, the washer thing might just give me what I'm looking for.

However the very soft springs are a killer as well which is why turn in suffers so greatly. A more progressive spring would be ideal. Kleemann's setup with shocks and springs speaks to me in this regard. As for Pss9's. I had them on the 911 and they were great at first and then took a dump after a while and I absolutely hated them thereafter.

I really can't believe that on an AMG you can't adjust the camber! WTF. Even my c43 was adjustable and made a huge difference btw.

I still think that the solution is a set of better springs and shocks that MATCH not just adding the springs as well as an adjustable bigger rear bar to dial out some understeer and it should be decent.

RawAMGpower

Renntech offers a rear adjustable camber/toe kit for $495.

sdsilverm3

I've had other suspension setups (H&R, Bilstein, Koni, Tokico, Tein) on various other cars and they degrade over time. My KW's on the C55 have not done that yet and it has been almost a year. The ride has been consistent though firm (too firm for some) but that's because of where I have the dampers set at. If the dampers are set too soft the front end tends to "float". Keep in mind that KW does not necessarily make a C55/V8 application so most people run the C320/V6 app. Hopefully that changes soon but KW has been busy building OEM parts for AMG lately so development has stopped.

dsC32

First of all, adding pressure to the rear tires increases understeer. You need to add to the front, and/or reduce rear pressure. Before spending a lot of money on suspension upgrades get front wheels and tires the same size as the rear. On my C55 I run 245/35-18 Hoosiers front and rear on BBS wheels (all the same size as rears) on the track with great results. Still have to reduce rear pressure about 3 pounds below the front to correct underesteer. Try the Mercedes negative camber bolts. They don't help much, but are better than stock. Only cost about $20, but you have to realign. I have read about people using the washers to get more negative camber.

anucci

Please excuse my lack of knowledge on this subject, but I am trying to learn as much as I can about this. I would think that increasing the pressure in the rear and decreasing it in the front would, in fact, reduce understeer. My reasoning is that decreasing pressure increases the contact patch and increasing the pressure decreases contact patch. So decreasing the front would increase contact patch (and traction), while increasing the rear would decrease contact patch and reduce traction.

Nick@JleviSW

I highly recommend you go with the PSS9 kit. IMO it is the best compromise between driveability and substantially improved performance. Not to mention the kit is very easy to adjust (just simple knobs for the dampening) and comes with a full lifetime warranty should anything malfunction.

We have these kits available on our site and we would be happy to answer any questions you may have about the kit. I personally have it on my 2001 325i and absolutely love the system.

http://jlevistreetwerks.com/store/pr...bf80509c262797

spr

Actually, decreasing the front pressure and increasing the rear does reduce understeer, check any suspension book on the subject. You decrease the pressure on the end you want to stick more. It is of course opposite with say bars as you increase the stiffness on the opposite end. You can also increase the pressure to reduce the stickiness. Running lower pressure in the front does however hurt initial turn in, but a 225 on a 7.5 is really not right anyways so it's moot. 225 should be on an 8.

I do like the idea about using matching rear sizes in the front. There are no clearance issues? I have also been looking into the 19's with 8.5/9.5 40 et setup.

What are the negative camber bolts you're speaking about? I didn't know mercedes actually made a product to increase the camber other than the washer idea.

Again, I have had pss9's on my 911 with mixed results and am grossly knowledgable with suspension tuning, I just don't know what is really available for the c55. I had the pss9's as dialed as you could and had gt3 adjustable bars and the car corer balanced etc.

I did however take issue with them wearing out prematurely and that is my complaint. Afterwhich since the springs are like 2x stiffer than stock it was poorly dampened even when the valving was increased it wasn't correct with the rebound and compression and was terrible, so I am not the biggest fan. Yes they have a lifetime warranty but there is the labor component of removal and reinstallation.

Thanks. Sean

Zeppelin

Wider tires on the front wil help understeer some, but it will not cure it. If you think so then put the 245's on the front and the 225's on the rear - guess what, it still understeers.

Camber bolts and the washers help some, but will not cure understeer.

In my pursuit to master this understeer issue I decided to go with a bigger rear swaybar. The problem is no one makes a big enough rear bar. So I am currently running two rear swaybars Yes thats right two. I have a 19mm H&R bar with the stock AMG bar on the rear of the car now. - Guess what - it still understeers The car is more nuetral than ever, but I still need more rear bar. I'm thinking of having a 24 or 26mm rear swaybar custom made.

I will track the car on 11/15 to do more testing with swaybvar sizes. I might go back to the stock front bar and leave the rear set-up alone.

nuclearhappines

That;s really funny man.

Eibach makes a 22mm sway bar for the W203 platform. Since your front end is CLK and rear end is C class... then the 22mm C class sway bar from eibach should fit your car... am i right ?

your stock rear sway should be 15mm

so 15^4 = 50625
adding an 19mm bar (which i have on order too :p) = adding 130321 of sway force

19mm instead of 15mm = 257% stiffer than stock.

both bars together
50625 + 130321 = 180946 = 357% stiffer than stock (go figure :p)

eibach 22mm sway bar
22^4 = 234256 > 180946

eibach alone = 462% stiffer than stock

how's that

sdsilverm3

I don't think 40 ET offset will fly on the fronts. 32's are already pushing it close with coilovers.

Zeppelin

The Eibach 22mm bar is not big enough either, I have driven cars with this bar.. The two bars I have on the car are welded together and boxed in between the bushings. It is much stiffer than the sum of the two bars alone.

spr

I like the idea of just using the eibach 22mm bar. When you drove the car with that bar, what was it set at? was it set at full stiff or is it non-adjustable? What about the brabus bars? I read somewhere they make them for the C. Anyone know the onfo on those? The closter the hole to the horizontal body is stiffer-

Where can I get those negative camber bolts? Part number?

I got the 40 et from Kleemann's website that's what they're rims are 8.5/9.5 both at 40 et. Maybe the fronts are supposed to be a different offset??

Zeppelin

The endlinks are in the holes closest to the body. In fact I drilled new holes as far forward as I could without them interfering with the lower control arm. 22mm is the biggest bar anyone makes. It is totally possible that you can't put a big enough bar in the rear to dial out the understeer. The rear subframe has so much play in the bushings that it might be flexing which makes the bar less effective.

Fifth Ring

Will an overly firm stab bar cause more inside rear wheel spin on tight turns?

Have you tried going (gasp ) softer on the front (springs or bar) to gain some rotation?

In the end, maybe you can't overcome the understeer. I have found that with a totally stock suspension, and with even-sized tires (245s) all around, I can invoke some rotation by lifting throttle or trail braking. It would never get so far as to threaten a spin, but I could definitely get some rotation, especially when the tires were warmed up.

Token picture 'cause I like seeing it:

spr

Lifting throttle is definitely improper driving technique. Trailbraking is taught but it is crude, dangerous, and really not as fast. Sooner or later with trailbraking you're going to be too hot into a corner think you can trail brake into it and then apply too much braking. The car will straighten out and off you'll go.

Whatever technique works for you... fine; but it will be slower and that's what it's really about right? Before I get flamed, know that I have been through many racing schools front, rear, and mid engine, and have a couple of dedicated race cars etc, so don't get offended. BTW my first race school I was in a professional drivers group and I beat every student and the instructor when I was 17, so maybe I am not the right person to talk to. Further when I had my stock 911 996 at the track I beat fully prepped gt2's gt3's 360's, an andial 993tt, flipped 996tt turbos and an NSX fully done with everything including supercharger driven by a professional drivers. I did go through a full set of pads though!

Anyhoo, I found that while driving the car in the canyons the other day, that the best way to really get the car to not understeer and instead be neutral through a corner is after making sure the car is neutrally loaded, (that is if coming out of the opposite corner to brake to reduce the opposite load and negate the transfer), is to almost set the car at an early apex slightly and throttle steer the car by flooring it, much like driving an all wheel drive car- flooring it before the apex. The turn in sucks, but it is neutral, has equal slip angle as such, and is the fastest your going to get with the current setup. This is of course after making sure to set the fronts pressure lower than stock, esp is off and you're not going to wreck into anyone while trying this! etc.

Fifth Ring

And you say that my driving is dangerous? Trailing throttle oversteer cannot be more dangerous than throttle induced oversteer -- and I don't do either on a public road!

Assuming it's controllable (and in an understeering pig, trailing throttle oversteer is VERY controllable), then it can make the difference between overshooting an apex and rotating to make the apex. If you're too hot into a turn, you need to slow down, and if slowing down also generates a mild rotation, then all the better. I won't recite my on-track experience, but I am a very conservative driver on-track and incident-free.

dsC32

I don't know where you get the idea that increasing rear pressure helps reduce understeer. It is exactly the opposite, and if this is what you guys are doing you are dialing in a problem. See my post above. Every article on reducing oversteer and driving instructor should confirm this. See for e.g.: http://www.tirerack.com/tires/tirete....jsp?techid=58

spr

Increasing the rear tire pressure allows less contact patch and slip angle = less grip certis paribus. Decreasing the tire pressure increases grip on that corner. Go read any credible suspension/driving book.

As for my experience or technique, I was giving my experience to help others. Your explanation on technique is that of an novice. I will waste my time no further educating you; go to a school and read some driving books instead of merely listening what some "driving instructor" who thinks he knows what he is doing tells you. Comedy.

If anyone could tell me where I can obtain the negative camber bolts and what their part number is I would appreciate it. Thanks Sean

sdsilverm3

I agree with SPR. You can even test that theory on a racing simulator. If you want the rear end to break loose you over-inflate. The C55 understeers by default which is why the suggested tire pressures are 33/37 psi (f/r). I guess they figured the offset would balance out the handling characteristics.

cntlaw

a very knowledge thread on the subject

Fifth Ring

Are you serious? You posts are disrespectful in tone and content. You cite your professed expertise as a license to make demeaning remarks (tagging others as "novices" "crude" or "dangerous"), when you could simply add your wisdom to the dialog without tainting it with ad hominem slights.

I will assume that you're not full of it and perhaps really have extensive on-track driving experience with all sorts of vehicles that you claim (although my BS meter is off the scale). I do note that you do not claim to be an instructor, which is perhaps a good thing.

Absit iniuria verbis.