Vibration under hard accelerating
Discussion
I've now got a vibration under hard accelerating but only from 70mph and upwards. When I disengage clutch there is still a vibration but not as pronounced when under load, likewise when cruising at e.g. 80mph but not as strong as when under load.
It doesn't happen when accelerating hard at lower speeds. It doesn't happen if I drop to 4th gear either.
I thought it was the propshaft UJ's so changed them for new gkn ones and it's a little better but problem not solved, the propshaft has both weights on it. I matched them back as they were when reinstalling.
Today after 200 miles there's a new subtle grating sound from passenger side as I was driving slowly, it appeared to be more pronounced turning right than left. There's no clunking or banging noise.
So I'm thinking in order of cost:
Wheel balancing (now unlikely with the new grating sound)
Diff bushes
CV joints - quite possible
Diff binding (but no clonks)
If it's the cv joints can I swap them around (from in/out to out/in) as a quick check?
500 miles ago I put new tyres on, new ggp shocks and 400lb springs which may have upset the balance.
Don't you love the homemade terminology of clinks, bangs and grates.....
It doesn't happen when accelerating hard at lower speeds. It doesn't happen if I drop to 4th gear either.
I thought it was the propshaft UJ's so changed them for new gkn ones and it's a little better but problem not solved, the propshaft has both weights on it. I matched them back as they were when reinstalling.
Today after 200 miles there's a new subtle grating sound from passenger side as I was driving slowly, it appeared to be more pronounced turning right than left. There's no clunking or banging noise.
So I'm thinking in order of cost:
Wheel balancing (now unlikely with the new grating sound)
Diff bushes
CV joints - quite possible
Diff binding (but no clonks)
If it's the cv joints can I swap them around (from in/out to out/in) as a quick check?
500 miles ago I put new tyres on, new ggp shocks and 400lb springs which may have upset the balance.
Don't you love the homemade terminology of clinks, bangs and grates.....The bigger engine chims have a flexible section on the exhaust just under the engine. This is there to eliminate vibration of the exhaust caused by the engine. Mine, being a 4ltr, doesn't have the flexible section but I do get the vibration. Mine starts approximately 80mph. It wasn't there when I first acquired the car, it first started after the exhaust had been off for maintenance.
I think they did away with the Flexy section or at least they did on my 2000 450.
Ive swapped over to sleeved exhaust and back a number of times which involved swapping over the exhaust tray and I’ve had two sets of new rubbers on the three retaining bolts that clamp the exhaust to tray as they soon seem to deteriorate and de form.
That’s where I’d look if nothing else vibrates on the exhaust side but in the O/p’s case I’m inclined to agree with the above, a wheel bearing would be my first thought.
Ive swapped over to sleeved exhaust and back a number of times which involved swapping over the exhaust tray and I’ve had two sets of new rubbers on the three retaining bolts that clamp the exhaust to tray as they soon seem to deteriorate and de form.
That’s where I’d look if nothing else vibrates on the exhaust side but in the O/p’s case I’m inclined to agree with the above, a wheel bearing would be my first thought.
A few thoughts for you, some mentioned above.
My local garage proprietor is as old as the hills, and he tests for wheel bearing failure by driving the car up the road and swerving it from left to right. The noise disappears when you unload the offending bearing.
I have also had a lot of noise from the rear of an Audi and thought it was failing wheel bearings, but it turned out to be cheap Chinese tyres, put on by the selling garage, that were going out of shape. You could feel the roughness of the tread with your fingers.
Possibly a harmonic vibration. 80 in 5th is 3000 rpm - do you get the same noise at 3000 rpm in 4th?
And finally, you are a long way from the first person to complain about vibration at 80+mph. It can happen when the wheel balancing is not quite perfect. Most noticeable on the front wheels in my experience.
My local garage proprietor is as old as the hills, and he tests for wheel bearing failure by driving the car up the road and swerving it from left to right. The noise disappears when you unload the offending bearing.
I have also had a lot of noise from the rear of an Audi and thought it was failing wheel bearings, but it turned out to be cheap Chinese tyres, put on by the selling garage, that were going out of shape. You could feel the roughness of the tread with your fingers.
Possibly a harmonic vibration. 80 in 5th is 3000 rpm - do you get the same noise at 3000 rpm in 4th?
And finally, you are a long way from the first person to complain about vibration at 80+mph. It can happen when the wheel balancing is not quite perfect. Most noticeable on the front wheels in my experience.
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