Practically Classics Forum

My '79 Silver Shadow starts vibrating at around 30mph and continues to do so the faster I go.
I can feel it through the steering wheel, seats and floor.
When coasting in neutral it stil vibrates, which should rule out the driveline.

I replaced :
- 4 tyres, front ones balanced on the car
- 1 steel wheel
- 2 front brake discs
- UJ's on both driveshafts
- UJ's on propshaft, whole assembly balanced
- front engine mount
- diff torque arm mounts
- rear crossmember mounts

Today I checked the tyres radial runout : all 4 of them have a maximum runout of between 0.1 and 0.15 inches.
Is this enough to cause these vibrations ?

Have you swapped the front tyres for the rears to see what effect (if any) that has?

Kev

Hi kev,

I haven't yet, but it is cetainly worth trying.
However, the run out on the rear tyres seems to be just as bad.

Benoit

you could jack one rear wheel up and see if it does it whilst in drive but stationery, that would help eliminate the wheels if it still did it. It sounds like a loose mounting- are the other engine mounts okay?

ecurie wrote: When coasting in neutral it stil vibrates, which should rule out the driveline.

Why would you say that?

This is a video of one of the wheels. You can see the distance between the tyre and piece of wood changing.

http://www.youtube.com/watch?v=Rz8D9wPRiZ4

That amount of run out would be more than enough to cause problems I would have thought...

That is quite a lot, you should fit the spare and try it again.

That has to be the problem! Its almost Oval.

jimmyybob wrote:That is quite a lot, you should fit the spare and try it again.

That won't help as all 4 wheels are like this.