High speed instability in the C-class

[philharve]

Hi All

Has any member encountered steering 'vagueness' that appears to manifest in the C-class as the 80/90mph mark is approached? It worsen the faster you go.

I have a C230K that exhibits this phenomina. I changed the tyres for ones with better grip/wear characteristics and only this week the steering damper was replaced. It was totally knackered. I also had a pair of lower ball joints replaced because there was slight wear in one of them. The car's suspension in fine. Despite these changes all I succeeded in doing was to move the point of instability further up the speed range.

I discussed the instability issue with both my indie and a dealer and both confirm that the curious handling chacteristic is not a design flaw, it is a characteristic of the steering geometry which also affects the E-class but to a lesser extent. The S-class is unaffected: it's rock solid at speed. It's also a heavier car. My indie added that the C-class is a relatively light car and its near vertical sides mean it is prone to side winds. Older C-class models are even more susceptable to the instability issue. It has been suggested that the car lifts as it travels faster making the steering feel light which contributes to the vagueness. This would suggest lowering the car might help.

My indie informed me that MB had a procedure for altering the steering geometry if a customer complained of high speed instability. The modification meant changing the alignment of the wheels in relation to the road surface. Instability is almost eliminated but tyre wear increases.

The C-class steering is setup for relaxed and comfortable travel. The C-class is not a sports car, C43 and C36 excepted, even though its top speed is 143mph. You need the skill and responses of an F1 driver to drive a C-class at autobahn speeds. It is an unforgiving and unnerving experience for the less skilled driver.

Has any other C-class, or E-class owner, experienced vague steering which generally starts to become noticeable at around 90mph? I don't have the skill or courage to push the car over the hundred mark, even if it was legal to do so.

REGARDS Phil

 

[ralphsanders]

Hi, I have a c200k and have had no problems with steering in fact it seems pretty good, as far as tyres go i have p6000's which seem good. It does get a bit light at top speed (only in Germany!) but then again as you say its not a sports car. I would get it checked out again and make sure all the bushes and ball joints are good.

One thing I just thought about the steering rack was replaced under warrenty when I first got the car (2 years old at that point), which had worn out!! so maybe they do have a problem, hopefully others will know more.

Good luck

 

[glojo]

My observation on this is any mass produced saloon car will have stability problems if you start throwing it about at speeds above 80 - 90mph. However on a motorway, dual carriageway or any other fairly straight road, your car should be rock solid. Just look at all the high performance vehicles within the range you are discussing C55AG, E55AMG, S600 (V12) not sure about the new S

Maff's car might not be a saloon car, but it would be fair to say it's no light weight?? and there does not appear to be any problems with his acheiving twice the speeds you are discussing?

John

 

[grober]

Shockers, rear suspension, geometry

There are so many things that might cause the problem you are experiencing. Most cars tend to "lighten up" a bit in feel at speed but Mercs especially should feel rock solid at 80-90. They were designed with autobahns in mind after all. I would be looking at your shock absorbers. they may be "within spec" for normal use but at 80-90 may be showing their age. High speed stability is often effected by the rear suspension also, so I would be checking the rear suspension and subframe bushes carefully also. The suspension tweak is probably some extra negative camber on the front which will wear the inside section of the tyre tread quicker. This shouldnt really be necessary but since there are permissable adjustment ranges the lowered esprit /sport models run slightly more castor / camber then the classic/elegance for example it could be possible. I would look at the shockers first, rear suspension second, and altered geometry last.
edit wonder why is this post in the interior section??
EDIT :-I'M CONFUSED now are we talking w202 C class 95-2000 or w203 C class 2000 onwards??

 

[Spinal]

I have a C-class too and have had no worries at speed; obviously I have never been over the speed limit in this country; but "a friend" in an "identical" c-class (W202) brought it to 110/115mph (with the wind behind, admittedly) without any stability issues...

 

[glojo]

High speed stability is often effected by the rear suspension also, so I would be checking the rear suspension and subframe bushes carefully also. The suspension tweak is probably some extra negative camber on the front which will wear the inside section of the tyre tread quicker.

edit wonder why is this post in the interior section??

Hi Graeme,
I am always suspicious of posts that are put up on April 1st. You have quite correctly pointed out possible causes, but:

I discussed the instability issue with both my indie and a dealer and both confirm that the curious handling chacteristic is not a design flaw, it is a characteristic of the steering geometry which also affects the E-class but to a lesser extent.

I wonder what type of dealer he went to??? drug dealer? antique dealer? Sorry for being flippant, but I just do not accept that these vehicles are unstable at high speed and I would happily drive at any speed along an empty autobahn

John

 

[blassberg]

haven't taken mine over 140 yet - but no problems so far...only another 15mph to go (or 16 if i derestrict it )

 

[Rory]

I have a latest version W203, although it's an estate. My first Merc, but I'm not thrilled with its stability either. Hard to put a finger on it, but it just never feels 'planted' on the road. If anything, I would say that in a straight line mines better the faster I drive.
Fast, bendy, motorway link roads, like say M42 to M5 to go North, can be real heart-in-the-mouth moments if I approach them at speeds that my previous 406s or Mondeos would have been quite happy with. The whole thing goes terribly vague.

I have a feeling (hope) mine might be tyre related - the Bridgestones it came with are noted for stiff sidewalls and I need to change them pretty soon. I've settled on softer riding Michelins - so we'll see.

 

[Birdman]

If C class saloons have a tendency toward medium/high speed instability I would call that a design problem by definition imo.

Try aligning the wheels to near the maximum angles for toe-in and caster, staying within the manufacturer's recommended range, to see if it fixes the problem.

 

[glojo]

We have a Sprinter high top medium wheelbase vehicle, now that van is indeed a very light vehicle, it is prone to feeling slightly unstable in very high cross winds, but she that must be obeyed sets the cruise control at 80mph (no doubt equates to a fraction over 70??) and we cruise up the M5 and across the M42. My better half does however comply with the roadwork speed limits.

Does the M42 junction also have speed limits where the bends join onto the M5??..

I am reminded of my hero Sabine driving a bog standard Transit van around the Nurburgring.... that thing flew.

I still believe you have handling problems.

John

is a relatively light car and its near vertical sides mean it is prone to side winds

 

[KLP 92]

I had similar probs on my W202. I replaced the shock absorbers with the Lorinser Bilstein spec ones from ebay and ever since then the handling has improved by 100%!! The car is now rock solid on a motorway. I regularly use the M40 which is prone to cross winds and its never been affected since.

 

[Thmsshaun]

I have driven my C43 up to the limiter and thought it felt solid all the way up to 155

 

[Alfie]

I have driven my C43 up to the limiter and thought it felt solid all the way up to 155

My original W202 went back three times to Mercedes to try and cure the instability. They lowered the front slightly which helped a bit. I think the facelifted W202 was a lot better from what I've heard.

 

[grober]

Interesting! there would appear to be a problem, at least in the earlier models. It should be easily resolved with some conservative mods. Have a look at the bilstein site. http://katalog.bilstein.de/ they list a lowering kit and sports shocks for your model.
edit should this not be in the technical-wheels and tyres section??

 

[Shude]

My previous W202 C230k did feel a little bit light around 130-140mph It had 17" AMG rims with relatively new tyres and AMG bodystyling. Did not feel unstable though.

 

[glojo]

My previous W202 C230k did feel a little bit light around 130-140mph It had 17" AMG rims with relatively new tyres and AMG bodystyling. Did not feel unstable though.

And what happened to this highly stable flying machine?

Many apologies, black ice, snow etc will always catch out the best of us.

John

 

[Shude]

And what happened to this highly stable flying machine?

It was sucked off the road by frozen grass!

 

[bagman1971]

Hi mate
I have a w202 c230k 1997 with ecu remap and pulley upgrade 17" amg alloys with 225,s front and 245,s rear. I have had it up to 145mph with no problems(handles like a dream). Recommend you get steering geometry checked out also tyres/wheels upgrade if needed!!!!!!!

 

[big x]

At 110 mph my w202 feels very planted. However,driving up to London this saturday there was a very strong tailwind. I thought something had gone wrong with the car and stopped and turned round and it felt normal again. It would seem if the low pressure area behind the boot is reduced the car loses stability,just the opposite to what one might imagine.
New shock absorbers, as with any car over 60k, help stability and handling.


adam