Cross winds & woolly steering?

[Phil D]

Hi
Just got back from a week in Scotland (better weather than Northern Spain in May BTW) I noticed that the car - W203 220 cdi - drove perfectly (as usual) on A roads, but on exposed sections of motorway it felt rather vague, very susceptible to cross winds, and just didn't feel totally "planted" on the road at anything over 70 ish - so much so that it didn't always feel entirely comfortable keeping up with the flow - any ideas guys ? - standard 15inch wheels with 205/55 dunlop eagles on the front

 

[Phil D]

actually I meant standard 16 inch wheels - other than that I'd welcome any replies

 

[television]

One way is to reduce the tyre pressures a touch to stop the wheels from bouncing, I suggested this to Phil Harve and I think that it helped

 

[Phil D]

cheers tv - but any reasons why this should be an issue? - loads of other "lesser" cars feel absolutely solid at much higher speeds
Phil

 

[philharve]

One way is to reduce the tyre pressures a touch to stop the wheels from bouncing, I suggested this to Phil Harve and I think that it helped

Hi Phil D

Malcolm did indeed suggest lowering the tyre pressures a tad when I discovered my car felt very nervous over anything above 70mph. I would go further and say it was positively dangerous. Bouncing wheels (over inflated tyres? weak suspension?) mean the car isn't adhering to the road surface as it should and this will be felt as a steering vagueness. You will probably find you are forever correcting the steering wheel to counteract the vagueness. This isn't exactly a relaxing experience, added to which having Corsa 1.2s passing you on the motorway because you daren't go any faster is a sobering experience.

I subsequently discovered that increasing the rear tyre pressures a tad also benefitted handling and stability. I had the steering damper replaced because it was bone dry.

However, some months ago during a routine service, my indie discovered the nearside lower wishbone bush was damaged but superficially looked A1. Both bushes were replaced to the benefit of handling and stability. Now both wheels should work together and not fight one another.

But could handling and stability be improved still further? I believe so, but I need to convince my indie that my shocks are past their best at 114,000 miles. I feel there is still too much roll present for a 140+mph car. My indie is adamant that MB shocks last mega-miles and if there is a problem it's much more likely to be soft/broken springs. He said he has changed them by the bucket load on other MBs but shocks last much longer. My springs aren't broken but maybe they have softened. How do you check?

I recently retired and used my MB to transport a ton of books home from my office. The boot, back seat and passenger seat and footwell were filled with books. But I was delightfully impressed at how well the Merc' coped. It's as if the extra weight dampened the roll characteristics. Maybe its natural for a lightly-loaded C-class designed before the Millenium period to be a bit twitchy at speed but regain its composure when carrying passengers and their luggage.

The suspension & steering design of the sportier C-classes do seem to be a bit of a compromise. My Celica was far more stable and therefore could be driven faster. But the Celica was a sports car and my C230K is a sports saloon and I will have to accept that in the handling stakes they are worlds apart.

One day I will replace the shocks and/or springs and I bet it will improve the handling without sacrificing too much of the ride comfort. But first I must convince my indie that I know what I'm talking about. He is MB-trained but he should not discount my 40 years behind a wheel. I know when something is not quite right.

REGARDS

Phil

 

[television]

I know what Phil means when he says that he know what feels right and does not.

Strange how one car maker can have a car like the SL that is so sure footed up to any speed, the 124s were also perfect at any speed, and then produce a car that feels so unsafe in the most popular model range, its beyond me

 

[Parrot of Doom]

Have the geometry checked and aligned via laser alignment. It sorted mine out and now it drives straight and true with little correction required even on a windy day.

 

[Phil D]

hello guys & thanks for the replies - congratulations on your retirement Phil - hope you enjoy every day!
I can't claim 40 yrs but it's 35 next month since I passed my test & I've driven all sorts since then from absolute heaps to a few Audis (whisper it a BMW) and two mercedes including the current one - like Phil I know I'm not imagining it when something just isn't right
seeing Parrot's post it occured to me that the giant road humps that I have to negotiate every day on a 20mph limit near my house could have knocked something out - although Malcolm's last post rather suggests that this problem is by no means uncommon on this model - is this the case
I will get the geometry checked and report back - any recommendations in my neck of the woods?
Phil

 

[philharve]

Hi Phil

Thankyou for the kind comments concerning retiremment. I'm a sprightly 56-yearer, going on 21.

Technically I'm a big fan of laser wheel alignment systems. Only two things deter me from having my steering geometry checked, one is cost and the other is what if the alignment is bollixed, i.e. performed by someone who isn't entirely competent.

Judging by the wear pattern on my tyres there's not much wrong with the alignment of my wheels. However, a professional check to confirm that belief would always be welcome.

As mentioned previously, I've done certain things to my car that have brought about big improvements to steering and handling and its no longer dangerous. I don't fear travelling beyond 70 as I once did. However, I have the feeling that if I attempted to travel at autobahn speeds, the instability barrier would return. Maybe travelling at these speeds with a fully loaded car would be an entirely different experience. But since I mainly travel alone, like most drivers, shouldn't the experience be the same?

I know very little about how Mercedes design and test their cars but it's my opinion that they probably undergo more rigorous testing because of their higher attainable speeds. They've got to get it right. But they don't always, as many an owner of a prematurely rusted Merc' will tell you.

As Malcolm states, some models are safe at any speed so why should the C class be different. Did MB make a mistake with the design of the C class? Or do they require all components to be in tip-top condition to give of their best?

REGARDS

Phil

 

[Phil D]

Hi Phil
retirement ? can't wait ! 54 this month but 30 till some bright spark puts a mirror in the way - anyway enjoy !!!!
looking at your car history I'm insanely jealous - dolomite sprint indeed - brings back a lot of memories when I was knocking around in an old morris minor!
the steering thing is interesting though - your earlier post about constantly readjusting the steering really hit the spot - in Spain in May I was very uncomfortable on the motorway between Santander & San Sebasstian - at the time I put it down to a lousy day, very wet & windy, & the fact that it was the first time I'd driven on the wrong side of the road for many years - looking back I was really scared - not something I'd normally experience & loads of people were flying past me in all manner of ordinary motors
I'll get mine checked & report back

 

[Parrot of Doom]

Judging by the wear pattern on my tyres there's not much wrong with the alignment of my wheels. However, a professional check to confirm that belief would always be welcome.

Unfortunately many aspects of the alignment wouldn't be apparent in your tread pattern. On mine the main thing 'out' of alignment was the thrust angle at the back. The car was essentially trying to steer from the rear wheels.

 

[television]

Unfortunately many aspects of the alignment wouldn't be apparent in your tread pattern. On mine the main thing 'out' of alignment was the thrust angle at the back. The car was essentially trying to steer from the rear wheels.

The above reminds me of some post 12 months ago where the rear suspension was worn, the whole sub frame I think was moving.

 

[Rory]

just didn't feel totally "planted" on the road at anything over 70 ish

I've used exactly the same word in threads to describe my car - mine's an estate, 54reg with 30K miles. It's never felt planted and I have no real confidence in the car at speed.
It's my first Merc, and arrived after opting out of company cars. So several things have changed, particularly that I own the car, and that it's my first RWD car for some time.
However I've been used to getting hold of cars by the scruff of the neck and really driving them, and the car responding. My car doesn't react well to being 'driven' - it's jittery, nervous, and really doesn't inspire confidence.

I've thought about getting the alignment set up (mine has the standard camber drift to the left, but the tyres are wearing evenly) but I too have read horror stories about it being messed up. It's supposed to be done with car weighted, so the comments about how philharve's car drove when loaded with books are interesting.

 

[philharve]

Thrust angles and rear axle steering

Unfortunately many aspects of the alignment wouldn't be apparent in your tread pattern. On mine the main thing 'out' of alignment was the thrust angle at the back. The car was essentially trying to steer from the rear wheels.

Hi Parrot of Doom

Thrust angles is something I've considered but as yet no work has been performed on the rear suspension components. I'm trusting my indie to spot anything wrong but it's not an easy task.

Would laser alignment on the rear wheels show an incorrect thrust angle whilst the car is static, sitting on a ramp? Isn't this a dynamic problem that appears only when the car is actually moving?

You may have supplied the justification for an alignment check. I'll speak to my indie about it.

REGARDS

Phil

 

[philharve]

Hi Phil
retirement ? can't wait ! 54 this month but 30 till some bright spark puts a mirror in the way - anyway enjoy !!!!
looking at your car history I'm insanely jealous - dolomite sprint indeed - brings back a lot of memories when I was knocking around in an old morris minor!
the steering thing is interesting though - your earlier post about constantly readjusting the steering really hit the spot - in Spain in May I was very uncomfortable on the motorway between Santander & San Sebasstian - at the time I put it down to a lousy day, very wet & windy, & the fact that it was the first time I'd driven on the wrong side of the road for many years - looking back I was really scared - not something I'd normally experience & loads of people were flying past me in all manner of ordinary motors
I'll get mine checked & report back

Hi Phil

I posted an item about steering vagueness some time ago when I first encountered the stability problem. My C230K does get deflected by strong crosswinds and you have to hold tight onto the steering wheel and constantly make steering corrections to stay on course. But what I found most alarming was having to take the same corrective actions on a calm day. That's what first alerted me to a problem with my car.

The most worrying aspect was that the faster I went the more serious the instability. At 80mph the car felt like it wanted to leave the road, either to the nearside, or worse, into oncoming traffic. The only solution was to backoff the accelerator. Below 70 the instability was not noticeable. I also formed the impression the front wheels were bouncing, however, I didn't get the same impression from the rears.

I have improved matters considerably but I have a feeling that all I've done is to push the point of the onset of instability further up the speed range. I am unlikely to find this point in this country, however, I might encounter it if I ever took my car abroad.

I still believe there is a spring and/or damper problem because the car rolls to much for my liking. My reason for believing this is watching the behaviour of other cars. I like watching car chase programmes in which the baddies are trying to escape the police at well over 100mph. Seldom have I seen the escaping vehicle roll from side-to-side. Vans do. All it seems to do is gently ride over the undulations in the road. I think to myself, 'now that's how my car should behave!'. Why doesn't it?

Instead, what I experience is a pendulum-like rolling motion and that means I have to hang onto the steering wheel for a degree of support which, of course, is not its function. Either the roads around where I live are unusually 'lumpy' and induce the rolling motion, or there is a problem with the car. I suspect the latter. Springs or dampers? I'm not sure! I've replaced the shocks on my Celica and experienced a dramatic improvement. I've never replaced springs before. Since these components work in concert, how can you tell which one is defective without removing it from the vehicle? The 'bump test' is crude.

If the rear bushes are worn, or gone soft, then it's entirely possible that the rear axle is moving in relation to the axis of the chassis. This would produce rear end steering problems. If this were happening I would expect to have to make steering corrections. By loading my car with books and applying a heavy load over the rear axle, I'm lessening the opportunity for the axle to move. By eliminating changes in the thrust angle, the rear end steering effect is also eliminated. When I previously reported impoved stability under a heavy load, I mentioned that the roll was reduced. I didn't notice any reduction in the need to make steering corrections. It felt that same an when driving without a heavy load. The car felt 'heavy' to drive but it was by no means unpleasant. My car coped admirably with speed bumps. I felt sure the car would bottom, but it didn't, even when I was travelling over them quickly.

My immediate concern is the roll issue. However, if I find a fix, I expect another issue will arise, one that is being masked by the roll issue. This seems to be a fact of life: you deal with one problem only to find it replaced by another. Life is dealing with a never ending series of problems. Death is the only reprise.

REGARDS

Phil

 

[Phil D]

"Life is dealing with a never ending series of problems. Death is the only reprise."

Kinda puts things in perspective ! Hope I've time for a few problems yet !

I'm going to get the geometry checked - can't believe that it's a major design flaw - given the numbers of C class out there surely there would have been a flood of "me too" posts otherwise?

I've got the car booked in this week for the last lap of the warranty repair on the smelly aircon issue - two day job, thank god I'm not paying - & I'll make some enquiries while I'm there, but will take it elsewhere to get any work done - will update you all with any news/progress
Phil

 

[Parrot of Doom]

Hi Parrot of Doom

Thrust angles is something I've considered but as yet no work has been performed on the rear suspension components. I'm trusting my indie to spot anything wrong but it's not an easy task.

Would laser alignment on the rear wheels show an incorrect thrust angle whilst the car is static, sitting on a ramp? Isn't this a dynamic problem that appears only when the car is actually moving?

You may have supplied the justification for an alignment check. I'll speak to my indie about it.

REGARDS

Phil

http://homepage.ntlworld.com/tom.jeffs4/car stuff/merc tech/geometry check merc.jpg

 

[scousetechie]

And I thought it was just me....

 

[Phil D]

fraid not...... I've been in touch with Parrot's people in Oldham - based on his experience & the company website I'm very confident they know what they're doing - unfortunately they're a bit out of the way for me so I'm likely to take the car in a week on Saturday - hopefully they'll get it sorted - will let you all know how I get on
Phil

 

[Phil D]

Update as promised - had the car at the dealers for the aircon job & asked them to check this out as well - they advised that the track rod ends were shot & fitted new ones - haven't fully roadtested it yet but got it up to about 80 on the way home & it felt absolutely fine - I'll probably postpone the geometry check for a while untill I can establish whether it's a 100% fix