Disco 2 4.0 severe vibration at approx 50mph and 80mph

[sponcom]

Evening all

My recently acquired 4.0 Discovery has a vibration that is particularly noticable at 48mph and 80 mph+. I know there are a multitude of causes for vibrations and I have read several posts but cannot really pin down the source - it all seems to be a bit of trial and error. I hope that by describing the symptoms people may be able to eliminate some causes in the first place and narrow down potential sources.

The vibration is vibrating the whole car but is very noticable through the steering wheel. Tyres are relatively new and I've just had the fronts rebalanced. The vibration at 48mph dissapears once you get past 50mph but the vibration starts as you go past 80 and remains quite severe and doesn't go away. The second vibration is also accompanied by low humming sound as if is the vibration is resonating the car. In both cases the vibration remain if I continue at the speed but put the car in neutral.

I am not sure whether the two vibrations are linked or separate issues.

At the moment I'm looking for pointers where the cause may lie. Could it be propshafts, UJ's, the rubber donut? It was suggested by another Disco owner that the panhard rod bushes may need replacing or that the kingpins in the swivels might need adjusting.

Any help much appreciated!

Thanks, Paul

[Tetsu0san]

Check your prop UJ's for movement. Even slight play could give you the symptoms you describe. I think yours will have the double cardon prop at the front so there are 3 UJ's to look at there. If the prop is out of balance that would cause this too, but that is a specialist job to balance one. See if looks as if something has fallen off either prop as they are weighted with metal strips that are spot welded on. You can usually tell if one has fallen off because that area will be cleaner than the rest of the prop.

It is unlikely to be wheel bearings or panard rod bushes IMHO, but you never know. Do you get excessive shake if you hit a pothole? If you do that would be panard rod or wheen bearings, or even preload on the steering, but a vibration at certain speeds does not usually happen through any of these.