Wondering front - W202

[concord]

Further to my post regarding unstable front over 60mph. I have now removed the huge plastic sump guard from the underside. Drove it yesterday and today, the car is fine now and for the first time I took it passed 100! and remained very stable.

The sump guard must have been the culprit, causing an up lift force, as the speed picked up, making the front lighter, and more prone to cross/head wind making the front wobble.
That was a relief as I was worried there was something wrong with the steering or suspension, Its a different car now.

 

[tom7035]

Further to my post regarding unstable front over 60mph. I have now removed the huge plastic sump guard from the underside. Drove it yesterday and today, the car is fine now and for the first time I took it passed 100! and remained very stable.

The sump guard must have been the culprit, causing an up lift force, as the speed picked up, making the front lighter, and more prone to cross/head wind making the front wobble.
That was a relief as I was worried there was something wrong with the steering or suspension, Its a different car now.

Not too sure about this one.
However, not exactly a sump guard, but more to keep all those electronic gizmo's up under the bonnet dry when the roads are running with water.
Dodgy without it I reckon.

 

[jberks]

Agreed, I wouldn't keep it like that. If you intend running it at 100 a lot, I'd get a deeper front spoiler instead.
That said, it will have been designed to cope with 100mph+ for the autobahn market so I suspect the improved downforce (or lower upforce) is merely compensating for another fault - shocks etc?.

 

[philharve]

Further to my post regarding unstable front over 60mph. I have now removed the huge plastic sump guard from the underside. Drove it yesterday and today, the car is fine now and for the first time I took it passed 100! and remained very stable.

The sump guard must have been the culprit, causing an up lift force, as the speed picked up, making the front lighter, and more prone to cross/head wind making the front wobble.
That was a relief as I was worried there was something wrong with the steering or suspension, Its a different car now.

Hi concord

What age and mileage is your W202?

Removing the splash guard is a novel solution to a familiar problem. Can't help feeling it's not the preferred solution though.

REGARDS Phil

 

[television]

Am I right in thinking that we will soon be seing a C230 with a spoiler on the front flying down the M5

Malcolm

 

[clive williams]

Not too sure about this one.
However, not exactly a sump guard, but more to keep all those electronic gizmo's up under the bonnet dry when the roads are running with water.
Dodgy without it I reckon.

The main reason for the undertray is to tidy up the undercar areodynamics as without it expect the fuel consumption to worsen by about 1-2mpg similarly there will also be a loss in top speed although, I doubt whether anyone will actually notice. For the sake of a bit of plastic the extra mileage/top speed looks good on the new car performance figures.

I agree with JB that the main culprit for the instability will be poor/worn suspension, which could be front or rear. By taking the tray off this is just masking the real (serious) problem.

Clive

500E
E320CDIT210

 

[concord]

Hi concord

What age and mileage is your W202?

Removing the splash guard is a novel solution to a familiar problem. Can't help feeling it's not the preferred solution though.

REGARDS Phil

Hi Phil
Mine has done 89K so far. but she has been looked after. full MB service and all that. I had the car checked out by two main dealers, and each time I was told, they found nothing wrong with the suspension parts or steering.
the car has had a new sterring damper and lower ball joints replaced in November last year by the previous owner.

Although one of the main dealers suggested to replace socks all round, fo £500, but would not guarantee any improvements! I must admit after removing the splash guard, the twitching has lessened a lot, but still is not rock steady.
Regards

 

[Iain the gadget]

How about the all steel undertray that can be bought from the stealers?

 

[philharve]

I had the car checked out by two main dealers, and each time I was told, they found nothing wrong with the suspension parts or steering.
the car has had a new sterring damper and lower ball joints replaced in November last year by the previous owner.

Although one of the main dealers suggested to replace socks all round, fo £500, but would not guarantee any improvements! I must admit after removing the splash guard, the twitching has lessened a lot, but still is not rock steady.

Hi concord

Your experience closely matches my own. All suspension components were OK but there was a speed-dependent instability I couldn't account for. I experimented with tyre pressures with amazing results. See other thread (Instability ... is it normal-ish).

My C230K is now at 114,000 miles and I took it to my Mercedes-trained indie at the beginning of last year and asked him for his opinion on shock replacement. Would it cure the instability? He was emphatic that provided the shocks haven't leaked, they were good for several tens of thousands more miles. However, tired springs are a common failing with Mercedes and he said he has replaced them 'by the bucket load.' It's a simple enough job but he could not garrantee it would cure the instability. He added that the C-Class is a relatively light car and this results in a degree of instability over poor road surfaces. It's slab-sided profile makes it susceptable to instability due to cross winds. The heavier E-Class suffers some instability but the heaviest model, the S-Class, is free of such vices. My indie drives a C180 and he reports my car handles better than his because it has stiffer springs and lowered suspension as standard. However, it does not compare well with an S-Class which is much heavier and has a different steering geometry.

You may be able to tweak the suspension settings and fit uprated components or even add aerodynamic aids but at the end of the day a degree of instability may remain. Then you have the problem of British roads, the poor state of repair and uneven road surfaces. These factors can induce instability in the best designed suspension systems and you may have to live with the fact that you may never totally eliminate it.

Regards

Phil

 

[bigasotonuk]

Hi,
Similar experience with my W202 230K (114,000 miles also) i replaced my shocks with Genuine uprated Merc units "seems" to of eliminated a lot of the instability.
Though agree with your mechanic re. shocks i,ve read reports that anything over 20,000miles and the shocks will be under performing by up to 50% from what the manufacturer wanted them to do, though they would still pass the MOT bounce test and as long as they have,nt leaked would pass the test.
My under tray got damaged about 30,000miles ago by a high kerb (had a big hole in it) was gonna replace it with the steel option but this apparently is very expensive (£750) so i did,nt bother. I noticed signs of aluminium corrosion and lots dirt and dust. Which i believe has been brought about by the hole in the undertray. Drove it without for 2-3 days i never noticed any discernable difference to the handling as previous posts have said driving without it is only masking something else more serious, shocks i,ll bet.
The plastic undertray has now been replaced, hopefully this will now stop the aluminium corrosion, and keep the engine bay clean.
After reading previous post may look at replacing my springs. (springs will be genuine parts, non-genuine springs SHOULD NOT even be considered reasons found in other forum posts).