feets

I ran my C55 at the autocross for the first time last weekend.The notorious Mercedes understeer is borderline tragic on this thing. Turn in is very hard to plant without dumping all your momentum and standing the car on it's nose. I'm seriously considering dropping C350 or even '05+ C230 springs up front to help get some bite up front. Have any of you guys tried this approach?

This car is my daily driver. I do not mind softening the ride a bit. A moderate decrease in spring rate would be manageable without requiring changing struts. After all, mine have 99,900 miles and are not likely at full strength these days.

I WILL NOT LOWER THE CAR.

Lowering springs are OUT. Not negotiable.
Adding more rear bar is not the answer for this level of understeer. That works for moderate tweaks but this car needs more than a bar change.
Alignment was set recently. It could use a bit more camber up front but I don't care to get all racy with it and eat the tires. Otherwise, I'd toe it out and gain some bite.

Be aware that autocrossing is not like a track day. On most tracks you've got the time and space to smooth out transitions and set up otherwise unruly cars. When chasing cones at speed in a parking lot you do not have the luxury of either time or room to set up a car. Everything is compressed and very rapid transitions are required.

Before people start blathering about driver mods, let it be known that I am an accomplished driver with a history of not only racing but also professionally instructing high performance driving. I do not claim to be at Lewis Hamilton's level but I can certainly get the job done.

rilonprime

+1

Would adjustable dampeners help with this? I've heard Konis can be good for modulating weight transfer, that can mitigate understeer.

feets

Adjustable shocks would help a wee bit but you would still have the problem of the spring rate being too high.

Accidental L8 apex

Disconnecting the front bar may help get the fronts to bite a bit better and is free to try.

tjts1

Swap the front and rear tires.

slize

What size tires are you running in the front? Also I just had a complete overhaul of my steering system. Had New control arms, sway bar links, bushings etc.. made a big difference.

feets

I'm running stock wheels and factory size tires.
Rear wheels do not fit up front.

The front end is in good shape with new AMG spec bushings in the thrust arms.

Disconnecting the front bar will make the rear really loose. I can already wag it around after the front hooks up so that is not a good idea.

tjts1

so get a second set of front wheels and stick them on the back. MB setup these cars with staggered tires for looks and to keep them safe understeer.

feets

I'm not looking for a bandaid. I'd like to find a real solution.

Good tires can make a crap driver look better than he is.
These tires will do the trick if the suspension allows.

tjts1

Weaker springs on the front is a bandaid. MB intentially setup these cars to understeer with staggard tires.

feets

Wrong.

Mercedes set these cars up to handle well and give a satisfactory driving experience in all conditions. Then, they turned in the lawyer-proof understeer.

I am trying to set the car up to be more reactive on a specific type of track while still being comfortable and safe in daily use.
Softer springs would be a proper change to tune the suspension.

You have to get the chassis set up before you throw tires at a car.

tjts1

No, these cars are setup for safe understeer at the limit with a big HP number. That why they put skinny tires up front, big tires in the rear and no LSD in a car that has more than 50% of it's weight on the front tires. You're trying to undo that for autoX, that's fine. But you're not going to undo the laws of physict by dicking around with springs. You still have an inbalance of grip no matter what springs you stuff in it.
good luck

feets

Stop.

Just stop.

You have no clue what you're talking about and are just rambling on trying to justify your previous statement.

That's the problem with open forums. Keyboard jockeys become know-it-alls because they have some tickle in their brain that makes them an instant genius for all to follow.

I love this part: That's awesome!
Spoken like a true neophyte who is totally out of his element.
I'm trying to USE the laws of physics to reach my goal.

Physics dictates that a stiffer front end will make a car harder to turn. Believe it or not, a big front stabilizer bar will induce a degree of understeer, too. Taking out some front bar will make the rear loosen up and that is not what I'm looking for. So, I'm leaving the bar alone and looking at a lower spring rate instead.

These are NOT big hp cars by any stretch of the imagination. They are down 140 hp from other AMG cars built at the same time. In fact, they barely make 60 hp more than the common V8 cars from that era. These were moderately powered relatively light weight performance sedans offered as a lower cost alternative to the more expensive E55. That's it. Mid-level performers.

Skinny front tires are part of the C-class econo-box platform. You can't put wide tires on the front of the car because the chassis was not originally designed with that attribute. The factory must leave ample clearance for tire chains and such in all wheel positions (turning, compression, rebound, etc). The fact that the AMG guys got to have their way with the car means that compromises had to be made. They simply can't stuff big fat tires up there without spending even more money on the car and making it entirely too expensive to produce. That E55 I mentioned has 245 front tires. Yes, a whopping 8% wider tire on a car with 29% more power and 17% heavier.
Lest you forget, the E46 M3 also had 225 front tires and wider 255 rears. It would walk away from a C55 on a handling course.

Don't talk to me about skinny tires.

For a road course the car is really nice but still suffers from a bit of lawyer-induced understeer. When the average driver feels the front end plowing they tend to let off the gas. That slows the car and usually results in predictable controllable behavior. When the average driver yanks the wheel and the rear comes around they have big problems controlling it and the result is usually an uncontrolled spin.That is far more dangerous to innocent bystanders and other motorists.

What I am doing with the car is at the limit of it's design and can be far more demanding of the chassis. Autocrossing may be comparatively low speed events but the immediate handling and transitional demands are FAR harder on the chassis than higher speed open track work. It takes a completely different chassis setup.

Show me a car set up perfect for autocrossing and I'll show you a marginal car for track day events. The opposite is true, too. Show me a perfect car for tackling the Circuit of the Americas and I'll show you a slow autocrosser.

Two different disciplines require two different setups.

On a slower track the C55 will hold on to the bumper of an E55 but won't come near it at typical fast tracks.
Put the two cars on the Horse Thief Mile at Willow Springs and they'll be fairly evenly matched. Move over to Big Willow and the E55 will be lapping the lighter, more nimble C55 in short order. The C55 will be pathetically outclassed.
That theory is put to an extreme in autocrossing. The E55 and C55 are in the same class. The big power of the E55 is crippled by it's high weight.

In short, you need to have a car set up for the discipline you seek. Last year I intentionally went for the C55 instead of the higher powered E55 for a variety of reasons. Among those was the crisper handling of a lighter and stiffer car.

The C55 is a not bad on the highway for my 60 mile commute. It's a bit choppy at times but not bad. On a road course it would be fairly well at home but not a world beater by any stretch of the imagination. At the autocross it is simply too stiff to get the job done.

I feel pretty sure that lighting the front springs would get the front end bite I'm looking for, smooth out the highway ride, and somewhat reduce the at-limit performance on a road course.

The reason for the post was to find out if others had followed this trail and, if so, which springs were used. There are a variety available but no spring rates listed.

Fantomas

Feets, you're selling the C55 short, it's a much better performer than the E55 everywhere but straight line. The E55 isn't even from the "sporty" tree of Mercedes family, it just has a monster of an engine in grandmas Buick. It reminds me of a supercharged Regal GS I once I had when I thought 240hp was a lot. Even if it does put down decent track times the driver wouldn't be having much fun. Yeah, I bought an E55....

Softer springs would definitely help with understeer but you're gonna need more front camber to take advantage of it, every transition is going to cause the loaded side to be lower than before, at the lower suspension state the camber might go positive negating any gains you could have had with a softer spring.

feets

I'm not selling the car short. I bought it due to its potential.

I'm not interested in going squishy up front. That would make things worse. There is a balance to be had and I'd like to find it.

Factory setups are compromises. There's more performance available.

SteveE400

I've been out of autocrossing for decades, but I used to race a rear-engine, air-cooled car (NOT a VW). Along with the usual spring rate mods, shocks, sway bar diameters and moment arm lengths, bushing materials, within certain of the classes, we were able to use any tires - street or track compound/profile. If you are restricted to street tires, well, you know all about that already. If, however, you are allowed to use race/track compound tires on the front along with street tires on the back, you may be able to attain a more neutral handling balance. We also used different tire pressures, as you probably do, depending upon how our cars acted on each track's pavement.

You're definitely out in the far decimal places of some of these modifications, and I wonder how many here would be truly competent to contribute.

feets

I was hoping I wasn't going it alone with autocrossing a C55. The car has lots of potential but I have to find it.

As a former racer you know all too well that a good tire can cover up bad driving. I know I'm rusty and don't want to hide behind R888s or Sport Cups.

johnng117

Quick fix, widen the front tracks.. with spacers.

feets

Spacers won't make enough of a difference. Thick spacers are bad ideas in a performance application.

daynger

TBH you have a bit of a weird approach.
Ie: You want the car to do well at autocross but you wont sacrifice anything (wheel alignment, tyres etc).
Being a daily driver and an autocross thrasher is a compromise in itself, the car cannot be all things all the time, at a certain point you need to make the choice between faster circuit times and street comfort.
You also seem intent on the front springs being the only thing that can help, which is not entirely true as you have been given a few suggestions already.

First thing i personally would focus on is wheel alignment spec and tyre pressures.
Next would be tyres themselves.
Then i would be looking into swaybars and possibly shocks and spring rates.

What are your wheel alignment specs?
Tyre types and pressures?

Also, TBH the M3 would have been a better choice, they turn better.

daynger

No different in running lower offset wheels if they are the correct spacers for the job.

feets

I have work Mercedes-Benz dealerships for 15 years. I still work at a Mercedes dealership. That experience has taught me that the 203 is one of the most reliable chassis and that 113 is one of the most reliable engines. Put them together and you have a pretty fun little car that should last a long time.

Autocrossing a daily driver is not that big of a deal. I am not looking to make an all-out race car. There are some things that can be done to improve performance on the track without sacrificing drivability. Going a little lighter on the front Springs is one of those things. The ride will be smoother and the car should turn in easier.
Running sticky tires means shorter life on the street or having to change the tires before going to the track. Other guys have talked about adding more rear stabilizer bar and having very little success with it. After you reach a certain point with bars you end up turning it into essentially a solid-axle.

I was monitoring tire pressure. I was trying to keep the fronts a little lower than the rears but not so low that I would start rolling over the side walls.

I am open to suggestions but I have already thought through the common solutions. Very few people ever think of lowering spring rates to improve performance. It seems counterproductive but can really pay off in some situations. I think they should work well in this situation. The question is which ones should I use?

tjts1

Hey snowflake, you're the one that started this thread *****ing and moaning that your ****box understeers in autoX. Now you're going to lecture me on how well balanced your heap of junk is? LOL go **** yourself. Be sure to let us know how those 4 banger springs work out for you because "wider front tires don't fit". And whatever else you do in life, don't forget to breathe retard.

Accidental L8 apex

First, the stock sized tires simply aren't enough to auto-x these pigs on. Won't stick up front and the tail wags the dog constantly.
Second, I'm less than convinced these can be made anywhere near competitive on-course and still be daily drivable. Both ends simply need a lot more spring rate to really hustle.
Third, this is at least the 2nd thread where you're coming off as an arrogant know-it-all. Which begs the question, are you really asking for opinions or just bored and showing us how much you know?

I don't really care because I don't know you, but it does remind me of asking someone what they want to eat, being told they don't care and then getting every one of your suggestions shot down. It's humorous.

feets

That's not my intention.

I'm hearing suggestions that have been made time and again but I haven't seen anyone have much success with those things. It always comes down to settling for a car that won't hustle and still be livable.
I really think the cars are over sprung. The suspension is too stiff for some things. After all, it's the hardest suspension package ever offered on a 203.
Lighter front springs are something I haven't seen anyone try but the theory seems to make sense. A softer front end will have more initial bite than a stiffer front end. It means that you keep the same rear end that can be controlled with the throttle. To me, it would make the car more lively.

As for the C230 springs, as of 2005 all non-C55 cars had variations of the 272 V6, not 4 bangers. The C230 sport package cars were a bit stiffer than necessary to provide that sporty feel.

On older cars Mercedes had you add up the points to find the proper spring for the car. Each model of a particular chassis would start out with a set number of points. Options installed on the car would add points. The more points you had the stiffer the springs were. They dropped that system a while back and now springs have regular part numbers and there is no indication of the spring rate.