Hey MB Folks, Jeff Here Hi!

It's very hard to explain but I'll try my best to draw it out....
I have noticed since taking ownership of my W203 that when at speeds over 65mph on pretty much any highway travel it seems the car's rear end wants to slide out from underneath itself on mild turns and even some straight aways.

Now, all of my previous vehicles have been Acura/Hondas or V-Dubs with extensive aftermarket suspension upgrades installed almost immediately after purchase, So I'm used to a ride that feels like it's "On Rails".

Yesterday I was coming home from work on I-275 and traffic was running pretty fast (70-75ish mph)
I was behind a stock Red W203 and as we were turning towards the left where the Highway makes a slow 90 degree angle heading from east to north, I noticed that the rear end of his car was all over the place when going over small gaps where the concrete slab connects to the next slab, The front end seems to take the cornering very stable but the back looks and feels like an Anti-roll bar is missing or the Shock/tire traction skips a step and almost slides away from the direction in which the car is traveling.
This also happens on some straight aways where the road slabs meet themselves...... Only on Highways though.

Is this common?
Do you know the issue I'm talking about?
Is this feeling going to go away if I upgrade to a Coilover or an Aftermarket Spring/Shock setup?



As we were going around this turn, I was feeling the sway issue along seeing the same issue on the W203 in front of me, but looking around at the other vehicles around us, This shifting was not a problem, which leads me to believe that the is only a W203 hiccup.

Any advice?
Can you relate?
I need to get this fixed, It's the only con I think I have come across in this car so-far.

Thanks in advance!!

 

hahahaha....i had the same story , especially when i upgraded to non staggered wheels...spacers and sways fixed it beautifully!

 

Its RWD, so your rear end will hop over gaps, I take those turns at like 90 plus some times and never give it a thought.

FWD will never feel like RWD in corners, remember its push vs pull.

Also the rear end does not step out your seeing things, Ive been in a caravan of 4 C classes on I275 75 interchange and they behave no different then any other rwd car.

Its called bump steer on FWD cars and I dont know if its just called bump reaction on RWD, but it how it is.

If the car had a traction issue the ESP would most certainly kick.

Also we have open diffs

 

I am closing in on 79000 miles on my original suspension and this is nonsense - you have something wrong with your car. My car feels better over 80mph than it does at 40. The high speed stability of my C230, whether it's just me or a car-load of people, exceeds that of the 135i by a huge margin and has always amazed me. Taking an exit or on-ramp in the C230 is drama free even at high speeds and with seams (like the 285/85 interchange in ATL Spaghetti Junction). The seams can be felt but they don't disrupt the balance of the car. The 135i, with the RFTs, on the other hand becomes all kinds of skittish in situations like that.

 

after 125k, mine is tight as a drum

 

yeah mine is tight too, although i have 4MATIC
a little note i will make about the rear suspension that kinda caught me off gaurd is that the springs and struts are mounted next to eachother? not with the spring around the strut as it is in the front. I dont know if this is anything different my C320's the only suspension i've ever really checked out but i thought that was intersting

although maybe coming from those slammed hondas and VW's that were as you said "on rails", driving a car with a softer suspension thats meant to have a smooth/comfortable ride for the driver (mercedes is leaned towards luxury rather than performance, especially in the lower class non-AMG models) is a big difference and something you have to get used to?
and if not, then put coilovers and sway bars on it and you'll be back on rails!

 

I think a "strut" is where the spring mounted to a shock absorber as 1 unit. The rear suspension of my 2007 Civic Si sedan was the same as the W203. Shock absorbers mounted next to springs.

 

^^ yeah sorry forgot that when its mounted together its a strut and when its sepearate its a shock lol, but yeah, that just caught me off gaurd when i took a look at them, i assumed theyd be together like the front

 

I think only the most pedestrian of cars have 4-wheel strut setups, but I could be wrong.

 

You can't really compared a honda with modified suspension to a mercedes with stock suspension. Its apples to oranges comparison.

But anyways, the front weight bias and the soft suspension tends to make the car understeer stock. Yes if you upgrade to coil overs and sways you will get rid of the understeer and can set it to bit of oversteer.

You also have to change the way you drive since fwd drives differently then rwd in cornering. These cars tend to turn better with greater throtttle then braking, so keep that mind.

The car turns like crap if you trail brake and you put a lot more stress on the front tires as well.

 

bilstein pss9 coilovers and h&r front and rear sway bars will significantly improve the handling.

But let me clarify something, your car will never be able to handle like an E46 M3. I had never driven an m3 until last week as i wanted to get a rough idea of how my car compares to a car built to handle.

The M3 in stock form handles very well the steering wheel feels heavy and repsonsive. The ride is a lot softer than my clk but it can handle slightly better. My CLK has literally no body roll, but the car is set up so stiff that its uncomfortable to drive sometimes.

I would recommend you switch cars to a car better built to handle in stock form instead of dumping a lot of money into your C.

I had big plans with my clk to make it into something special although now i feel i have a good handlind car but its not worth investing anymore money into it. Perhaps i am being too hard on my clk being that i have driven modified 996TT porsche's but i know what i want and the clk cannot deliver. But i can vouch that the pss9 coilovers and sway bars have transfrormed my car and it can handle pretty well for such a heavy car that is not balanced well!

Simply put i have an awesome handling mercedes but it can't compare to an M3 or porsche

Mike

 

It seems as there is some misinformation in terms right now...

Bump steer: Any car can get bump steer. It has to do with the effective pivot point of the suspension upright in the front and of the tie rod coming off of the steering rack. The radius and axis of rotation for both is different, so as the suspension moves up and down, different paths are followed by both. But because the tie rod cant change its length, it pushes out (or in) causing the wheel to turn a little bit.

The reason why the rear of a RWD car pitches sideways on a bump in a turn is due to instability. When the rear hits a bump, there is an instant where there is reduced weight on the axle. When this happens in a turn, there is also a lateral force pushing the car sideways. Lateral force plus reduced traction = slide. All cars exhibit this, but is more pronounced in a car that has driven rear wheels. A FWD car will pull the rear in line, a RWD car will push it out of line. Grab a pen by the tip and slide it on a desk, the rear follows. Push the same pen from behind and it is unstable and will turn. This can get very dangerous, it can be just enough to upset the car in low traction conditions to the point of loss of control. Or when you are on a motorcycle... I had a close call with that once!

Strut: A strut is a damper that also acts as a linkage of the suspension geometry. It does not mean that its one with the spring or not. BMW's and Porsche's have a strut front end. Instead of having a lower and upper A-arm, they only have a lower. The strut acts as the upper linkage. This is why you can adjust the camber on a BMW (and most cars). The strut maintains a constant angle to the wheel as it travels up and down, so moving the top of the strut on the shock tower will change the angle of the wheel as it pivots at the end of the lower A-arm. This is a cheaper and simpler alternative, and why its preferred by most manufacturers for both front and rear. Porsche is really the only true sports car to make a front MacPherson Strut setup perform. Most high end sports cars use an Upper & Lower A-Arm set up (or multi link setups like that on MB's)

Mercedes does not use a strut front suspension on any of its current cars. I'm not 100%, but I'm pretty sure the rear on the W203 is not a strut setup either. However they do run a ridiculous amount of caster. This is why the wheel tilts as the steering is turned.

Hope this helps to clarify some things up!

 

w203 uses struts in the front and independent suspension in the rear. I believe the previous generations of C-classes had indepedent suspension in the front as well.

Mercedes did it to offer more interior space and cheaper cost.

 

OK! I stand corrected... I was going off a parts diagram that was mislabeled and found the right. The W203 does have struts in the front, the W202 didn't. The diagram was labeled for a W203 but was actually a W202! My bad!

 

thanks for all that info, and i always wondered about that, when i had my wheels turned all the way and parked it looked like i needed a camber adjustment! lol i was freaked out when i saw how tilted the wheels were

 

How Right you are!!

Yesterday I ended up staying home from work with a very queezy stomach.
I tried to take it easy most of the morning but by noon I was bored of daytime TV and sitting on my butt.
After venturing down to my Garage looking for something to do, I decided to jack the rear of the car up and investigate the suspension.... especially after reading all of your opinions and info in this thread.
Low and behold I found my problem.

It seems my rear drivers side dampner has sprung a small leak.
The base is saturated and there is a bit of dirt buildup near the top, So it seems to have been slowly happening for a while.
Maybe this is the reason the car feels sloppy to me at highway speeds. No?

I guess it's time to invest in upgrading the suspension.
I Bought the W203 primarily because I needed something Safe and good on MPG, large enough to transport my two young sons around, And Something in my Budget but still looked Nice and didn't need constant mechanical attention.

 

My rear suspension is total crap. It seems to drive like a mustang. With all the axle hop, and slosh associated with it. I just thought the chassis was way too soft (like butter on a hot day)

I think its time for me to jack up my car and check for leaks in the rear struts.

 

Im sorry but I haven't driven a single car in the Mercedes line up that handles the way my M3 can. The C55 we had was nice on straights but the M3 out handled that piggy by far.

My advice is to switch into a different car or buy an M3 if you really want the handling aspect of the car down.

 

I haven't driven a single car from the MB line up that can handle as well as the e46 M3 can. The C55 we had was quick on the straights but not very well in the corners(body roll like a ****) whne compared to the M3

Get yourself into a different car if you want a true car that can handle and perform, but trust me the M3 isnt cheap

edit:sorry for the double post, my comp is freaking out

 

Glad you found the problem. I'm sure that once you get this squared away, and given you have decent tires and correct alignment, you'll be back to enjoying the freakishly good high-speed stability these cars offer. I had to have a rear shock absorber replaced under warranty at around 30,000 because it had began leaking. I forgot about that till today when I was going through the paperwork.

Overall, you didn't make a bad choice. How many miles are you at? In the nearly 54,000 miles I've put on my C230 since July of 2008, it has asked for only routine maintenance past warranty. The tires wear a bit quicker than some of my previous cars as do the brakes, but for the added performance in both handling and braking I'm willing to make that trade-off.

 

Thank You!!!

I'm just about to turn 59,000

 

I'm at 120K miles on my car and the stock suspension has been wonderful (Not M3 wonderful though )

I never had the problem of unstable rear as you've described when I take high speed corners, maybe the tires are worn out on that red W203? or is equipped with really crappy tires?

I would say my C turns better than most family sedans out there (Camry, Maxima, Accord)

 

It very well could have been .

I've come to the conclusion of just replacing both rear shocks with either OEMs or something not so pricey.
Within the past few weeks my Fiance's car has been giving us problems left and right, So the decision has been made to temporarily make the Benz Her car as I have found a New toy to well...... Toy With. lol

The New hoopty is not a Mercedes.... but it's still of German Make.