Vibration at 55mph or over

D

D16PJM

Member
I have been chasing a vibration for months now and wondering if anyone can now point me in the direction of other things to check, so far I have replaced the drive shafts which did help but not eliminated the problem, I have placed the propshaft and checked everything is tight on the rear end, it has new bushes that were fitted before my ownership, where to look next ?.

Thanks Pete
 
Check the rear wheels are balanced properly and there are no defects in the tyres ( bulging sidewalls etc ) also the rear wheel bearings.
 
diff extension shaft bush is common? Engine mounts can create vibrations but i'm guessing that doesnt seem right?
 
Warped rear brake disc,,slightly binding rear pads!
Diff extension bearing on its way,top up or change diff oil and see if that helps!
Exhaust just touching somewhere at speed!
How do you feel the vibration?
Steering wheel,gear lever,seat,general buzzy feel from all round!
 
I don't really feel it in the steering so more from the rear, the diff has had fresh oil, discs look o.k and just pasted MOt so would of thought a warped disc may of showed up, may look at wheels and tyres next, in the ideal world if there was a local car that had a couple of hours to spare I could try some different wheels but haven't seen a P6 around here in years.

Pete
 
Hi Pete,

Given the speed with which the vibration makes itself apparent, the most likely culprit as Pat mentioned will be wheels and or tyres. Are the tyres more than 5 years of age?

Carry out a thorough inspection and have them balanced again. If they are more than 5 years old, having them replaced with new ones would be strongly advised.

Lets know what the outcome is.

Ron.
 
The first thing to check for with any vibration at that speed is the wheels and tyres. Probably thrown off a lead weight from one of the wheels.
 
had the wheels balanced today and they spotted that one of the wheels was slightly different with a larger bore in the centre where the wheel bearing pokes through, I had all the wheels balanced and put the spare on the rear as it had the same size as the other side, but my vibration is still the same.

I am assuming its diff related now, either mounting or mechanical, any idea's or a garage around kent/south London that may know there way around a P6.

Thanks Pete
 
check all the rubbers and brackets at the front of the diff extension are present and correct... they can disappear over the years...
 
Hi Pete,

You mentioned in your first post that you had replaced the tailshaft (known as a propshaft in the U.K). Can you verify that the arrows on the yoke shaft and tailshaft proper were aligned? They need to be for balance purposes, and if they are not, then you may well have found the problem.

Barring that, has the harmonic balancer on the pinion extension case been disturbed at all?

Ron.
 
SydneyRoverP6B said:
Hi Pete,


Barring that, has the harmonic balancer on the pinion extension case been disturbed at all?

Ron.
Click to expand...

I have no idea what one is but where is it and is it easy to change.
 
D16PJM wrote,...
I have no idea what one is but where is it and is it easy to change.
Click to expand...

It will be positioned on the pinion extension case, and unless it has been damaged in some way, it should not be removed or replaced.

Did you check the tailshaft arrows for alignment?

Ron.
 
SydneyRoverP6B said:
D16PJM wrote,...
I have no idea what one is but where is it and is it easy to change.
Click to expand...

It will be positioned on the pinion extension case, and unless it has been damaged in some way, it should not be removed or replaced.

Did you check the tailshaft arrows for alignment?

Ron.
Click to expand...

Thanks for all your help, will have a look but sure the alignment was fine, been so busy with starting a new job.

Pete
 
Sorry to drag this one up from the depths, but did you ever find the source of the vibration, please, Pete? I've noticed a similar vibration with mine, but I haven't quite worked out where it's coming from. It feels more like a vertical oscillation, rather than a shimmy, so I don't think it's from the front, it slowly gets worse, until it peaks at 70-75 mph.

I don't think it's warped rear discs, as there is no pedal pulsing under heavy braking.
 
Hi Martin,
You may have done this already but have you swapped wheels front to back or better still if poss off another car.
We done this at work after several balancing attempts turned out to be faulty tyres even though they looked ok.
P6 wheels are not the best for balancing as they dont run true even when new, and the centre hole is not completely round.
Balanced mine with the 5 stud attachment for our machine with better results.
Clive.
 
Cheers Clive, unfortunately I can't just swap the wheels round as I'm running different sizes front and rear, and the rear ones won't fit on the front! I thought what I might do as the first step was to measure run-out on the tyres with a dial gauge. I know it won't take into account the loading on the tyres, but it might show something.

If not, I'll have a good look underneath, to see if I can see anything obvious, and if not, go to a tyre place to get the balance checked as a first step.
 
Baron von Marlon said:
It feels more like a vertical oscillation, rather than a shimmy, so I don't think it's from the front, it slowly gets worse, until it peaks at 70-75 mph
Click to expand...

What's your propshaft like? Is the splined front part aligned correctly? There are some Harvey's posts on this. Is there too much wear on the splines? Is the diff extension nose sitting at the correct height, has all the damping pads fitted at the correct places, and is the front mounting nice and tight (they get soaked will oil that leaks from the front seal, and the rubber softens considerably).
These are all things to consider while you will be underneath the car.
 
Is the engine level in the engine bay? DId you check the rubber that supports the front of the diff extension case. (Diff extensions can leak rotting this rubber and then your diff sits too low at the front. It can also clonk more on taking up drive when it moves!)
 
The engine is level as far as I can tell. I'll check the diff mounting rubbers and the propshaft when I next get under there to have a look.
 
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