Bad vibration for a 560 SEL

[bigNgold]

Hi!
Is there any kind soul out there with suggestions for the problem on my 560 SEL?
The car has a very bad vibration that starts at 60 MPH and gets so bad the faster I go the bonnet shakes!
Bought new wheels from MBZ (£ouch) the tyres are all good, the wheels have been balanced at least 6 times, the propshaft has been replaced and it is head scratching time. The car is booked in for Drive shafts and the wheel bearings will be checked and likely replaced. But the problem is I dont want to be blindly rebuilding the car for a problem someone may have experience of. I have to fix this problem as it makes the car an unpleasant drive and there is clearly something very wrong.
Please contribute your suggestion!
Thanks in anticipation.
Regards john

 

[Myros]

by your description all the action seems to be

at the rear. Have you had the front looked at? I'm thinking maybe the steering damper might be suss. Do you feel the vibe throught the steering wheel or the brake pedal at all? I'm not sure the wheel bearings would give you a vibe. A screech , a groan, a rumble, but not sure about a vibe.
Are the brake discs OK, if they were unevenly worn you would get some kind of a vibe. Does the vibe seem to be related to the speed, i.e increase the faster over 60 you go, or is it just there as a constant thing?

 

[Blobcat]

A few thoughts;
Are the wheels round?
Did they balance differently on each of the 6 occassions?
Were the wheels dirty when balanced? - I have had caked mud on the inside of wheels of a hire car which made it shake so bad the gearbox fell out! (It was a fiat)
Did the problem start with the new wheels?
Try and find a tyre dealer who can balance the wheels on the car

 

[bigNgold]

Hey !
Thanks for coming back at me so quickly!
The brake discs are new (less than 1000 miles), the wheels are round and so are the tyres (we thought of that one!) The problem has always been on the car since I bought it 6 years ago thinking it was wheel balance! But it is getting worse! I really don't think it is wheel balance or tyres. It is speed related and the faster you go the more intense the vibe gets. It doesn't come though the steering but through the whole car. Please keep suggesting as you may suggest something we have not thought of!
Thanks ever so much for your replies!:

 

[Blobcat]

Propshaft?

 

[jberks]

Engine / gearbox mounts? If they are jumping about a bit. Had it once on a rwd ford.
How is tyre wear?

 

[Myros]

I'm thinking airflow related

maybe a loose undertray in the engine bay, or the slipstream catching the rear valance wrong. It wouldn't take much misalignment to set up a vortex at 60mph and more.

 

[television]

Wheel balance often shows up on the steering wheel, very slight,before the car starts shaking, and a slight touch of the brakes will often cancel it.
The wheel bearings will not cause it, that leaves prop shaft and engine mounts, there is not much else.

Malcolm

 

[davidsl500]

When I had my tyres replaced last year I had what I thought was badly balanced front wheels which caused a shuddering above 55-60mph and got worse as the speed increased.

I had some 3mm spacers fitted to the front at the same time since I was a little concerned about the clearance. Turned out that the spacers were the cause of the problem. Apparently Merc Wheels are hubcentric fit which means that the wheel centre must locate on the good bit of the protuberance of the hub - if not then the wheels can be torqued up wiht the wheel off centre and thus they turn out of true. Spacers removed and everything spot on now.

 

[television]

When I had my tyres replaced last year I had what I thought was badly balanced front wheels which caused a shuddering above 55-60mph and got worse as the speed increased.

I had some 3mm spacers fitted to the front at the same time since I was a little concerned about the clearance. Turned out that the spacers were the cause of the problem. Apparently Merc Wheels are hubcentric fit which means that the wheel centre must locate on the good bit of the protuberance of the hub - if not then the wheels can be torqued up wiht the wheel off centre and thus they turn out of true. Spacers removed and everything spot on now.

Is this so david,with all of the expensive wheels lke Lorenser, I would have thought that the spacers would have a groove and flange to extend the original hub, keeping the hub concentric.
Nice to know though, recommended spacers twice this week, I had better be careful from now on. Nice to live and learn.
Thank you. Malcolm

 

[bigNgold]

Thanks!

Thanks to all of you for your suggestions. The wheels are indeed round so are the tyres, they have been off the car to be rebalanced for the umpteenth time! The steering damper is fine and the vibration comes through the whole car. The hub bearings are about to be checked over. This could be interesting as they may have a wear pattern that is causing the problem. My C class has done sympathy since being fitted witha new gearbox flange and that is another area we shall be looking at. We are also going to check the driveshafts. Its definitely cyclical and builds up with speed. If I get to the bottom of this I will post a solution!

 

[jordanlott]

560SEC brkes always on

On my 560 the brakes are coming on a bit while driving and the disks heat up and then there is a very bad vibration through the front. Does the car stop on its own when you slow down?
see my link on jordanlott
my post below

Hi,
I own a great 1989 560SEC which i use as my main car now even though I own a couple of fantastic SAAB 9000´s.
It runs great but the brakes come on after a few minutes of driving. I can still drive but the front disks start to overheat.
The rear ones come on to. I have removed the wheel and the calipers release easy enough when pushed back so it does not seem to be a pipe blockage problem. Some times when I restart the engine the brakes release for a while but then come back on.Some times they release on thier own while driving.

Two issues that might give a clue;
The only other brake issue is that some mornings the pedal travels nearly to the floor before working but then pumps up quickly.
The three warning lights for ABS SRS and ( I forget the other initials ) sometimes come on shortly after starting and if I restart they go off.

It must be electrical I feel. Anybody got ant Ideas???
Thanks
Jordan

 

[jimsinessex]

This may be a complete red herring but a pal of mine with an old Rover P4 also had the rear brakes coming on of their own volition and after stripping and overhauling almost everything to do with the brakes without success he changed the flexible hoses. Bingo, the problem disappeared, but why?

He cut the hose in half and found it had delaminated inside. The detached lamination was acting as a crude non return valve and trapping some pressure at the wheel cylinder.

Jim