Vibration at motorway speeds

[anderoo]

I have some rather annoying vibrations in the car which start at around 70mph and get worse up to and beyond 80mph. Car is a w203 C350, 77,000 miles.

I've had the wheels checked for dents, and the front nearside wheel does have a very small dent (pothole casualty), but according to the local garage it's so slight that it shouldn't make any difference and is too slight for any type of repair.

Wheels have been balanced and alignment checked. After the balancing, it has improved a bit, but there's still something there.

Even though the alignment was spot on, it does pull slightly to the left. Also, the front nearside brake disc has a single, deepish groove around its centre, which didn't used to be there. Seems a bit of a coincidence?

The vibration doesn't seem to come from anywhere in particular, but I think I can feel it mostly through the seat. Yesterday on a duel carriageway I noticed the empty passenger seat vibrating as I drove along.

It seems to come and go a bit too. It's pretty much always noticable at 70mph+ but it varies in intensity. At its worst, since having the wheels balanced, it's annoying rather than alarming.

Any thoughts welcome before I take it to a garage - I don't want to go throwing parts at it...

 

[MancMike]

I thought you said it happens at motorway speeds?

Given it improved after wheel balancing, but is still there, suggests it wasn't balanced very accurately.

Have your tires had repairs in the past?

 

[anderoo]

ha

No tyre repairs - tyres are in good order.

 

[Rory]

It seems to come and go a bit too. It's pretty much always noticable at 70mph+ but it varies in intensity. At its worst, since having the wheels balanced, it's annoying rather than alarming.

Mine does this - the varying bit, at least. I reckon it's there even at idle so had concluded it must be the engine mounts but they perform OK in the usual tests. I'm 99.5% certain it wasn't there before the car's last major service, done at a dealer, and it's been suggested it could be related to the air filter mountings. I can feel it in the steering wheel at idle but obviously with a diesel there's always going to be something there.

I don't use the car much and the last couple of times out in it I'd forgotten about the vibration and it was only when I got home I realised I hadn't noticed it.

On your car if it only happens when moving then other things to consider would be the propshaft or it could even be gearbox related.

 

[anderoo]

Interesting, thanks. So far I have considered warped disc(s), stuck piston, wheel is actually more buckled than I'm led to believe, engine mounts, transmission mounts - but I'm pretty car illiterate so hopefully the good folk here will help narrow that down before I get it looked at.

Seems from reading around that this type of thing can be hard to diagnose without replacing a load of bits and seeing if it helps, so I'm keep to avoid that if possible.

 

[Stratman]

It could also be a propshaft bearing or rubber mount on its last legs.

 

[bob6600]

ha

No tyre repairs - tyres are in good order.

Are they retreads? Or budget?

 

[anderoo]

Are they retreads? Or budget?

No - continentals on the front, pirellis at the rear, plenty of tread all round and no damage.

Propshaft bearing - would that be expensive?

 

[PobodY]

No play in any of the suspension components? - I once had an annoying shimmy that turned-out to be a loose hub nut.

 

[anderoo]

Update - just a buckled wheel (pothole damage). The local garage that had a look reckoned it was a tiny dent and that the wheels were properly balanced, the indie I then took it to said the wheel was badly buckled and the others were not very well balanced. Lesson learned again. It is repairable, so in the meantime they've lent me a replacement wheel, and driving home the vibration was gone

They checked all the suspension components and engine/gearbox mounts just to be sure - all fine.

Guess it shows the importance of getting a second opinion, if nothing else...!

 

[anderoo]

Oh, I also asked about it pulling ever so slightly to the left and the guy reckoned all mercs to it - it's because of the camber of the road. If you drive on the other side of the road, it pulls slightly to the right. I tried it on the way home, and it's true!

 

[MikeInWimbledon]

A tyre specialist vs Mercedes specialists....

With all due respect to Main dealers, MB specialists and garages, if it's a wheel balancing / alignment issue it's worth hunting down your areas best and biggest tyre specialist. In my case Micheldever tyres, which is a full 50 miles / hour's drive away from my home.

They have fantastic kit and a real dedication to their arcane art. They can pick up nuances that you didn't even notice. And usually they're as cheap as the bloke down the road.

Let the garages do the routine oily bits.

 

[Smart320]

I used Micheldever Tyres a few years ago for my XJR and though they were excellent both for keen prices for tyres and especially sorting tracking and vibration problems. I was 60 miles away at the time but unfortunately too far away now to make a trip economic