Vibration, feels like tyres - need some clues

[pjb]

Folks,

Been experiencing vibration at motorway speeds in my SWB pajero. Had the tyres (33x12.5 bighorn) balanced, no improvement.

Vibration is first noticable at about 80 km/h.
Mostly gets worse with more speed, although there does seem to be sweet spots.
Can't feel it through the wheel (at all).
Doesn't matter how much jandal. Backed off, coasting, accellerating, neutral, same same.
Frequency seems too low (coarse) to be driveline, feels exactly like an unbalanced wheel feels like.

Took it back to the alignment place. They checked it again and suggested I must have worn shock or trailing arm bushes.

Dropped the shocks out, bushes are fine (although the crush tubes can slide axially in the rubber, but looks like it was made that way).

Next step: Either drop the trailing arms out to have a look at the bushes there, or swap some old A/T tyres and rims on and go for a drive to see if that makes any difference.

Can't really see how trailing arm bushes would influence wheel vibration... But can't really tell the bloke at the tyre place that he's wrong either.

Any advice?

[ClassicCruiserSpares]

How old are the tyres? have you had them off the rims to check for mud stuck in the beads or bits of mud and rubber in the tyres?
Any bolges in the tyres?

[Heath]

driveshafts out of balance - climb underneath and look for a clean patch where a weight may have come off.

UJ's failing under load?


Could be a tube has fallen apart and now a tyre is like a tubeless but with chunks of rubber inside - it happens.

[andrew007]

i have had this problem twice now,i had put a small crease,more like a deep scratch in my drive shaft on a grade 5 trip.had it re-tube problem solved.

[benorange]

i would say drive shaft to

[NJV6]

Drive shaft would be a pretty 'fine' Vibration.

Mine was a fine vibration, much faster than a wheel and in the end put a new diff and rear housing in it!

[pjb]

Cheers guys, thanks for the tips. Tyres are pretty new, and they've never really been that great even when I first got them.

Chucked on a set of A/T wheels and went for a burn. Even at 120 there was no trace of a vibration. Can't be the drivetrain then right?

Anyhow, had a close look at the trailing arm bushes (where they join on to the diff), they aren't in the best condition. So I suppose I had better sort those out. I don't have much confidence that they'll make much difference though...

Beyond that, maybe I'll go back to the tyre place, again.

[Heath]

tyres gets my vote then. when you swapped them and it went away that did it for me.

[tweake]

either the tire guy is shit at balancing or possibly one of the tires has a slight bulge out in the tread of the tire. possible broken inside the tire but not much external.

had a vibration the other day and tire was bulging out the centre of the tread with plenty of steel showing. not far off blowing out.

[pjb]

Got a point there Heath
Well, I'll be pretty rancid if a tyre is out of round - only done a couple of thousand ks on these things!