So has anyone tried dialing in the stock suspension on the C55 to improve the balance? The car understeers too much for my liking, so I'm considering throwing 235's on the front, moving the battery to the back & adjusting the alignment. Actually, I haven't looked, but is the alignment adjustable on these things?

 

I know that going from my older V6, C280 to a C43 V8, that it really needed a lot of extra work to get it to handle anywhere close to right. That extra weight hung out over the nose really hurts the handling.

 

The factory makes camber bolts that can give you up to 1.3 degrees of negative camber. You can also get some caster and this should give you some needed camber when you turn the wheel.

Then you may want to go for a Carlsson Coilover kit for this makes the car car far mor neutral than stock. If you need more camber you can go with some bushing from renntech or other tuners who allow for serious amounts of camber. The camber will help make the car turn and make the tires wear evenly.

Watch out when you change the tire sizes for the ESP system is set to have a set ratio for the differnece in rotations for the front and rear wheels. Taking the front and going larger makes the wheel rotate less and this will throw the system off. At the track we ran a C32 with very worn front tires and brand new rears and the car was virtually useless. The ESP system thought the car was oversteering in every corner at speeds where no skid was possible.

235/265 is safe and 225/255 is good as well. In 19 inch wheels you can use 235/265. A 245/275 would work but this will require serious fender modifications to work without rubbing.

Good luck

 

In Germany they sell a snow weight. It fits in the back where there is a void near the wheel arch. I think its about 60 or 80 pounds of lead.

 

Why would he want to make the car heavier? This might help make the wheels grip in the snow but it will not help with understeer. Take weight out of the nose not add it to the rear.

 

The idea of nett weight and performance is only valid when the wheels have good contact with the road.

 

Sorry if I am off base here, but I have never seen a Mercedes battery that wasn't in the trunk already. They do that to protect it from the elements and prevent the nose-to-nose horror situation of getting a jump from another car or roadside assistance. This way, someone can just pull in behind you facing the correct direction.

Things you can do though are to replace stock parts with lightweight stand-ins. 235 tires and lighter wheels will probably help.

Look around though, maybe some things can just be relocated to be on top or behind the front axle.

Hope this helps.

 

Does the car have a fundamental aerodynamic problem ? You can only do so much with a lighter car and then it becomes a kite unless it can push down ?

 

I don't really understand what you mean by a fundamental aerodynamic problem, but my kneejerk reaction is to say "No".

I think you would have to do a hell of a lot to make the car fly like a kite and the hood provides plenty of downforce.

Porsche's have almost a 65% rear weight bias on some of their cars and they don't pop a wheelie when launching, rather they get some of the lowest times and produce some of the least understeer. They actually tend towards oversteer for this reason. They do get a little squirrely over 125mph, but they never become unsafe, nor would a C AMG.

The current car, as is, is around 54.5%/45.5% bias. You don't have that far to go on a 3400 lb car. 150lb of weight reduction or shift would bring the car to 50/50. This is desirable for neutral handling and not unattainable.

 

Using a Porsche as an example is an instance of aerodynamics which the Benz sedan doesnt have. Unless you own both then I think we can leave it there as a comment.

Having watched Le Mans on TV and seen these million dollar racing cars sailing into the sky I would say that moving a small sack of potatoes from one part of the car to the other doesnt make any sense. But you suggest lightening the front makes the front stick to the road. I would like to know the cut-off point where improvements in this factor no longer yield tangible benefits.

 

Maybe this is a first for Merc (but I doubt it), in my C55 the battery is located up in the engine compartment on the right side, and it's no lightweight. I'm used to my BMW's & M3's which pretty much all have the battery in the right rear of the trunk & 50/50 weight distribution with crisper turn in. I want to reduce understeer & improve turn in, so more neg camber, less toe in, wider front tires & moving the battery all are in the cards for me. Maybe if those mods don't do enough I'll have to look into different spring & damping rates with an adjustable coil over kit. I'll have to put the car up in the air & check out the suspension to see what I can do. Camber bolts & bushings sound like a good start.

 

Miroj, I can't tell if you are trying to mess with me, or if you just don't know how what you are saying sounds.

What I am saying is that your posts for the most part seem to be contrarian in nature rather than productive. I also find your tone to be sarcastic and slightly bellicose. Consider yourself aware of what I have read in your posts and try to correct them before your next post. You must not treat everyone this way because otherwise I could only assume you would be banned from the forum. I am going to try to answer your posts as plainly and neutrally as possible.

As to your comment on a snow weight, yes they do sell one, and you can make one yourself. It would improve rear traction, but it would not likely reduce understeer, but rather just increase the total weight of the car, overloading the fronts further. Not only would this not likely improve the front to back handling, but also you are now stressing the sidewalls of your tires with more shear and reducing their lateral grip in turns encouraging lateral sliding. This is why people don't go to the track with a bunch of bricks in their trunk. The snow weight is to help you get rolling from a stop and apply a little more pressure to the ground while accelerating when you are driving in snow, not improve your handling in the snow. At any rate, you are talking about enhancing rear grip while Rbaker was talking about enhancing front grip. Experiment with this if you have a performance car, and I think you will see what I am talking about here. This is one reason why you can throw a Lotus Elise into a turn better than a G-Wagen.

The next post you made is much simpler to deal with: total vehicle weight and distribution always affect performance, whether the tires have a perfect contact patch or an awful one.

The next two posts you made were kind of about the same thing, so I am going to deal with them both at once. You said that you can only do so much with lightening the car and then it turns into a kite. This is true. If you lighten a car and if you attain a speed that produces more lift on the car than the car has in summation between curb weight and downforce, it will flip up into the air. Mercedes-AMG had a lot of trouble with this with the CLK-GTR. Personally, I think it happening once is the most it should happen and then it should be addressed so it doesn't happen again. In this case, the car did have a fundamental aerodynamic problem because they setup the downforce on the car so that they could get as little drag as possible. The only problem with that is that the car went faster than they thought it could and created the aforementioned problem with flipping up into the air.

Production versions of AMG cars do not have aerodynamic problems, they are designed with tons of downforce and weight to make 155mph on the autobahn seem like 30mph in a tank, that is to say that you feel very planted at maximum governed speed. They know their customers will remove the speed limiter and also design the car to have more than enough downforce to attain those speeds. With all due respect, you are comparing cars that weigh around 2200 lbs travelling at speeds of up to around 191mph to a 3400lb car that travels at speeds up to 155mph.

The weight you were talking about is more like a small man than a small sack of potatoes, so let's say that is a better estimate.

The problem with understeer is not because the front isn't heavy enough, it is because the front is too heavy. It normally occurs under heavy braking when there is a forward weight shift, due to inertia, and it overloads the front tires which are using most of the traction to stop, let alone turn. By lightening the front you are going to reduce the load experienced by the front of the car and thusly you will have more available traction to turn since you aren't using as much to stop. This turns understeer into neutral steer without having to change anything else. This is the principle everyone is discussing here.

The point at which lightening the front no longer yields tangible benefits is when you start upsetting the weight bias to the rear a la Porsche 911. You will have gone straight from understeer to neutral steer to oversteer. This is just as undesirable to most people as understeer, so I listed it as a point where you might want to think about what you are doing.

I hope you found this informative and now understand better why your comments were close but slightly misguided. Keep at it and I am sure you will have the hang of these principles in no time at all. If you have any further questions, please PM them to me rather than playing this out in front of others. I wish you luck. Take care.

Lastly, the porsche was an example, and yes I have both driven and talked to 996 owners ad nauseum about the handling of their vehicles. It was not a comment. It was a statement of fact.

 

Rbaker,

Wow! The battery is in the front. That obviously shocks me. This must have been something they went to when changing from the W202 to the W203 body type. I owned a few w202's as well. Listen, everything you have said is right on target.

Adding wider tires up front in good weather will increase total front traction allowing you to add more steering control under maximum braking. ABS obviously helps with this too.

Moving the battery to the back will help for sure, but may be tricky in terms of wiring and warranty conditions on your electrical system. An alternate consideration may be to get a lightweight battery like an Optima brand battery.

Adjusting the alignment of the vehicle will definitely give you crisper turn in and reduce understeer, but at the expense of risking uneven tread wear.

Stiffer springs and dampers should reduce frontward weight shift under braking and reduce understeering as well.

I am sure you know what you are doing because it sure sounds like it.

I would go with your plan 100%. But, if for some reason that isn't enough: consider lightening parts up front and shifting non-critical parts behind the front axle.

 

You need a new point of view. That recto-cranial impaction is starting to warp your outlook.

 

What is this princess tale about 50/50 distribution. How do you account for cornering and braking forces with an idle weight distribution. Its totally meaningless. The only facility in the car that needs upgrading is the nut behind the wheel.

 

After reading miroj's post I thought to myself, "wtf is this guy being serious?" Rguy, very informative rebuttal.

 

Oggle,

Thanks. You can't convert them all.

 

50% of cornering is skill and the other 50% is ability. Farting around with the front end .......

 

Making statements like this, you've got no idea about vehicle setup or dynamics.

It is possible to dial out understeer through several methods:
- Stiffen rear roll resistance
- Soften front roll resistance
- Decrease front tire pressure (creating larger contact patch)
- Increase rear tire pressure (creating smaller contact patch)
- Increase front wheel negative camber (creating flatter contact patch while cornering)
- etc., etc.

Go to any track day, or road race, you will see this.

On any good race team there is a suspension engineer, responsible for ensuring that the car is handling at its best, given the existing track conditions.

Changes in track surface, weather conditions, tire compound/construction, etc. all require changes in the suspension settings, in order to gain maximum performance from the car.

Weight distribution will significantly affect the handling of the car, but I doubt that you'll be able to shift 150lbs without major cutting/modification of the car. Better to try to find an adjustable suspension (adjustable sway bars with coil-over shocks).

 

I once asked my friend how he managed to cover 1000Km of distance in 4 hours in his Mercedes travelling on less than perfect Australian roads. He said it was all about knowing the limits of your car.

He told me a story about driving at 220Km/h and taking a bend in his car only to find that the vehicle just beyond the exit to the corner was a heavy fuel tanker.

So he was able to stop his car and in the process managed to lift the rear wheels off the ground giving him only visibility of the road directly in front of the car. When he came to a halt he could quite clearly see the rear on the tanker just in front.

What you are telling me is that also the driver of the C55 that took me around the streets of Sydney at 120Km/h on wet roads was also a figment of my imagination. Using the paddle shift and brakes to stop just 6 inches behind a car whilst taking a corner and slowing down at the same time from 140Km/h to 30km/h speed on a wet road.

All I hear is how to correct the defects in the car - I can see where the defect is. I think all these people talking about car modifcations have some kind of a share in performance business or tuning shop because I never heard any of this from people that drive better than I do.

 

Its also true that a skilled driver can lap you in a car with stock setup even though you have invested thousands in coilovers and suspension engineering. The best racing bang for the buck is Bondurant or Skip Barber etc...

My personal opinion is that few of us could even maximize the stock setup on this car let alone exploit the limits of a massaged setup. Its interesting to talk about and modding the car is fun to but the reality is that if it makes you faster at all it will be very marginal.

 

 

No question, the nut behind the wheel should be tightened first. However, once that nut is appropriately tightened, then dialing out the understeer is the next step to making the drive more rewarding (and quicker on the track).

As far as exploiting the limits of the car in stock form . . . anyone who tries to do this on public roads is an idiot. This is for track events only.

As far as braking hard enough to lift the rear tires of a Benz . . . I gotta call BS on that one. Sorry Miroj, you simply haven't got a clue . . .

 

Well this is it ..... there are those that can and those that cant. That is why people laugh at modders. He is simply one level beyond your skill set.

 

I heard it all before ..... which do you think is more likely ? That I am a complete idiot or there are people out there who can drive better than you. The odds are stacked in my favour.