jsaccio

With 4k on my C55 the one thing I would like to improve is the handling around turns. I guess I like to take turns a little hard and the back end starts to slip until the ESP kicks in.

What are the best things to improve this? I assume there is no free lunch so I will probably give up something too. Perhaps I'm just dealing with the weight limits and design of the vehicle.

Any help would be appreciated.

thx, joe

x-tian-230k

If you have the money, coil overs would be the best bet. Those will run ya around 1k or more depending on brand...... If you want a cheaper alternative, lowring springz will help you also...... Renntech springz are expensive but will improve your handling...... they will also lower you car and have a much more agressive stance...... Sent you a PM with more info....

2QUIK4U

get the AMG Nurburgring Suspension, it is specifically tailored and designed for our cars.

more151please

how do we get that?

Bux

2dr conversion

BlackC230Coupe

Easy, just get a set of coilovers, (anything but H&R) some KW's or PSS9's with a set of either H&R or eibach sways and the car will be changed.

vraa

Have you also tried a set of better tires?

rguy

I hate to disagree with a lot of people here, but hey...it's a forum I guess. I would start with forged wheels and 19" wider rubber up front. I believe what you are trying to dial out understeer. If I am wrong, then maybe a tunable suspension is a better way to go for you, but I think that the current stock amg suspension is fairly adequate. If you go to an inevitably stiffer suspension, your only going to gain handling on smooth road. On rough road, you will lose handling ability as the wheels won't follow the road as well and will not keep as consistent of a contact patch. If you live in an area where not all the roads resemble race track, then I would think long and hard before using the broadsword and work more on the scalpel technique. If you can't spring for the wheels, then I would give RENNtech a call and talk to them about their rear subframe modification and their sway bar set. Mercedes tends to cut some corners in the name of comfort on the rear setup and the rear modification helps out in almost all ways.

If you are going to go with a stiffer suspension anyway, then I would almost argue you have to compensate by using lighter wheels that are easier to push down to the ground when the road falls away and less jarring when pushed up. I hope this helps.

rguy

Lastly, when picking a tire, I would go with a rounder shoulder, since you will be pushing hard through the turns, it would be nice to have a more progressive break away with better feedback up to the limit.

cntlaw

I wish I understand these technical tricks but pity I am a car mechanics idiot. Would it be if you can understand the effectiveness of what they have suggested; you would not be asking the question in the first place?
cnt

CynCarvin32

I am going to have to disagree a bit. I had a c32 and so does a good friend (still does). We went through every combination of tires, wheel sizes, suspensions and tire pressures around and found that the best upgrade was likely a set of coil-overs and an adjustment to the tire pressures. Just going to larger fronts did not help very much at all and this ends up throwing the ESP system way out of wack. Just going to a bigger front and the same sized rear with chang the rotational circumfrance ratio for the front and rear wheels and this will confuse the heck out of ESP. We had an issue with very worn front tires and brand new rear tires (at a track event) and the car was un-drivable because ESP intruded in every turn regardless of speed and slip angle.

Going from 225/45/17 and 245/40/17 to 235/40/18 and 265/35/18 did not make the car that much different. It just looked goofy because it had the SUV C32 ride height. C55's have 18's So I would start with the suspension and I would also never bother with 19's if you are looking for performance upgrades. 19's look nice but dent, weigh more, and take more power to rotate.

As for tire pressures, W203's work best with 39 front and 37 rear (rides a little firm but not too much so).

Good luck!

CynCarvin32

This to can be tricky. The W023 is really camber challenged up front (in need of far more negative camber). For any type of spirited driving you will wear the letters off the side of the tire and your first tread blocks will be nice and feathered ... if not totally polished off.

The best tire we could find for the car was a R-Comp tire with an ultra strong sidewall -- and a VERY sharp anger on its sidewall. The more rounded tires like the Toyo T-1S just had more sidewall wear and felt more skitish at speed. In the end both street and R-Comp tires last only 2 days at the track so might as well go for the really sticky tire!

This is our findings on a C32 but the C55 could be different.

E55AMG99

Didn't he say the backend was breaking away? If so, why would he want to dial out understeer which would make the front end turn in harder and make the back end come around faster?

What do 19" wheels have to do with this? Why wider rubber up front which will cause the front end to bite harder and turn in better with the same results as above? In most cases 19" wheels will be heavier and cause an overall loss of handling, braking and accelleration performance compared to the same width but lighter 18" combo.

Why round shoulders which would provide less of a contact patch and therfore lower cornering performance? Unlike a motorcycle, isn't one of the goals of a properly tuned car suspension to keep the tire as flat as possible through the corner?

Why would a stiffer suspension only help on smooth roads? Isn't it also the goal of a properly tuned suspension to keep the tire on the road as much as possible and to limit body roll?

Ideally when racing, you do not want to use tire pressure to compensate for suspension deficiencies. The best way to check for proper tire inflation is to chalk or paint a stripe across the tread and down the sidewall. Run a few laps and look for the way the stripe has worn. A properly inflated tire will have worn the stipe evenly across the tire and not on the sidewall. Be careful not over or under inflate your tires. Sometimes suspension deficiencies will prevent the stripe from wearing evenly. Use you head!

Even without having any experience with a C55, if the problem is the back end coming around, I'd look there first. Is everythign as it should be? Are there any missing or broken items? Sounds stupid be you;d be surprised what can happen. If everything is working, here are a few things that I've done at the track to help prevent oversteer. BTW, the fastest way around the track is with a slighlty oversteering car if the driver is up to the challenge and the electronic babysitter will allow it!

LOWER Front tire pressure - see warning above
RAISE Rear tire pressure - see warning above
SMALLER Front tire section
LARGER Rear tire section
LARGER Front tire aspect ratio
SMALLER Rear tire aspect ratio
LARGER Front tread depth
SMALLER Rear tread depth
NARROWER Front wheel width
WIDER Rear wheel width
HEAVIER Front wheel weight
LIGHTER Rear wheel weight
MORE POSITIVE Front wheel camber
MORE NEGATIVE Rear wheel camber
MORE TOE IN Front wheel toe
MORE TOE IN Rear wheel toe
MORE NEGATIVE Front wheel caster
STIFFER Front springs
SOFTER Rear springs
STIFFER Front shocks
SOFTER Rear shocks
STIFFER Front anti-sway bar
SOFTER Rear anti-sway bar
SOFTER Front bushings
STIFFER Rear bushings
MORE Front brake proportion
LESS Rear brake proportion
REDUCE Front spoiler
INCREASE Rear spoiler
MOVE FORWARD Weight distribution

rguy

Well, if the rear end breaking away is the problem with the handling on the C55, then it is the driving that needs improvement rather than the car. The c55 is set to at least what I would call a moderate understeer balance. If the rear end is all loosey goosey, then either the rear tires are bald in relation to the fronts (which could definitely be the problem), or their is imprudent throttle usage in the corners. So, you want to dial out understeer to make the car handle more neutral, that is to balance the grip of the fronts with the rears.

19" wheels allow you to have a shorter and thereby stiffer sidewall, so they hold their contact patch better when you are turning. In this car you want the front to bite harder and turn in better. The stock 18" wheels are about 27lbs up front and about 29lbs out back. That is without tires. They are heavier for design aesthetics, cheaper casting technology, and therefore needing more material to provide the same strength as a forged rim. Most 19" formed rims (that aren't chromed or any other weird thing) will way between 19 and 21 lbs in 19" sizes that fit our cars. Therefore you can enhance handling and have less rotational mass if you desire. This is expensive, hence my note about swinging the cost.

With a sharp angle tire, the tire shears and then gives. You never really know when this is going to happen, although you can get good at guessing based on experience. With a round shoulder, you allow the tire to gradually lose its traction, thereby accurately communicating to the driver where you are in losing your contact patch and producing significant slip or even spinning out or off. There are people who know a lot more about this than I do, but this is what I have gleaned in the short time I have researched the why of it. It is probably true that you would have somewhat less traction than a square angle shoulder, but you lose the progressivity and thus there is a balance to be individually sorted out here as well. Figure out what you want in your car and go from there.

The goal of a suspension is to limit body roll (not the primary reason though: this is the primary arena of sway bars rather than springs and dampers), lower the center of gravity and keep the tires pressed to the road. And I believe I explained fairly well why a stiffer suspension will not help on rough road, but to reiterate, you are going to have a really stiff (less compressible) spring that is going to be good at keeping the car on the ground, but the suspension is neither going to allow the wheels to fall away in road undulations as well nor is it going to allow the wheels to come up as fast on bumps. On an ideally designed suspension for an agressive road car, you are going to limit body roll (but let the sway bars do a lot of that), lower the center of gravity without risking bottoming out or scraping speed bumps and what not, and have bound and rebound on shocks and spring stiffness that will allow the suspension to change position readily with differences in road elevation (follow the road surface). There is a sweet spot in all of these adjustments that allows you to have what you are looking for, and the problem must be approached systematically rather than by just looking at one part adjustment. In the case of the c55, it is my feeling that adding 10mm to the front and 20 mm to the back tires while maintaining approximately correct circumference ratios will allow you to enter the corners at higher speeds with roughly the same balance. A stiffer rear sway bar will dump some rear end traction, but will bring the rear end more in line with the front end traction and dial out understeer while not inducing oversteer. I hope this gets at most of what you were talking about, there was a lot to go through. And yes, outside certain ranges tire pressures are a bad idea to change, but you can change them within their specification for load and wear. I would be suprised if you did those things to a mercedes and got good results, but I am guessing that you are talking about your other cars here. At least with my style of driving, the car understeers, not oversteers. My goal would be to enter with and maintain higher cornering speeds rather than to try not to have the rear end break loose, you have to be doing something wrong like stabbing the throttle or lifting after the apex for this to happen.

rguy

Please excuse the mispellings I was coming off a crack high when I wrote this tidbit.

E55AMG99

LOL! No worries

OK. I was asking the questions to see if you had a method to your madness or were just spewing. Looks like you know what you are talking about but I think we are confusing each other here. Your comments seem to be about C55 in general and not this particular one. I tend to agree that all MB have a serious amount of understeer from the factory and oversteer is mostly driver error. My suggestions were addressing oversteer by itself and not considering the general nature of street cars to heavily understeer and driver inexperience.

CynCarvin32

I must say that the only way to have the rear of a W203 come around is to drive with ESP off and use far to much throttle. The car understeers and the only way to make it "drift" is by lighting up the non LSD rear axle.

I have never seen a W203 snap at the track but I have seen a C55 in the rain run with ESP off and the guy did oversteer off the road. That was simply because he was to hard on the gas for the conditions. I think he was trying to free himself from a C32 (on bald racing tires) that was glued to his bumper .

In normal conditions, driver inputs can correct the oversteer but the understeer can only be fixed with very slow corner entry or serious suspension work. 4 degrees negative camber anyone?

Well to be honest if you trail brake very late into a corner the back end WILL step out but that is more of a trick for making the car turn and not to make it go sideways.

rguy

What I wouldn't give for 4 degrees on a track day. On normal roads though, I think a couple of degrees would be as high as I would go. Obviously you know this, different settings for different situations.

rguy

e55amg99,

Yes, that would make sense. If you were just talking about fixing oversteer in general, then almost all of what you said was true.

I was applying it to the c55, and you are right about him (english is a masculine language) complaining about the rear end breaking away. I must have been coming off a crack high then too. Maybe I should cut back on the crack? I am noticing a pattern here.

Take care.

E55AMG99

No worries. Personally, I prefer the feminine kind of crack!

AMG&AMG

I think a good tire will sort it up.... I recommened Michelin Pilot Sport 2 and Pilot Sport Cup for the track....

CynCarvin32

Dunlop SP Super Sport Race costs 1/3 the price. And when you kill the tires in a single day $$$ is the leading factor!

Not a fan of the Sport cup but for a road car the PS2 is hands down the best

CynCarvin32

Well as sad as it is I have never seen a W203 that did not have really poor tire wear even when driven on the street. There is something very odd with the W203 being that it still has poor tire wear with neg 1.8 degrees of camber. The car needs 2 degrees for street drivingand up to 4 for track.

rguy

Must be the suspension geometry, something that is unlikely to be fixed by a coil and shock switch out. That sucks. I think they must have fixed it though, because my tires are wearing like a champ. Come back to the C side.

CynCarvin32

well the rear tires always wear perfectly at the track. No feathering, no cupping, perfect tire temps across the tire etc.

Only if the front suspension was equally as well set!

We always are working at fixing the front so we will let everyone know if we find a fix!

No springs shocks etc wont fix tire wear issues completely but it can help redcue the load on the tire and that may make the tire last a bit longer!