(T) Strange wobble/vibration [differential?]

I recently bought a 2004 1.6 3door stilo which I am very pleased with but it has a strange wobble/vibration.

The whole car feels as if it is wobbling from side to side but it does not come up through the steering wheel. The wobble begins to start at about 50mph, is at its worst at 60mph and stops at above 70mph. It only does it when accelerating ( light or hard), which can be in 3rd,4th or 5th gear, as soon as you remove your foot from the accelerator the wobble stops.

I have had all 4 tyres replaced and the tracking altered. None of the wheels appear to be buckled. An independant fiat specialist has checked the engine mounts and cv joints but they are not able to find the a fault. There is a slight oil leak from the gearbox which is being monitored.

Has anyone had similar a problem and did you find a cure?

its a balancing problem , all 4 wheels need to be balanced, some garages think you only have to balance the front two,

out of balance front wheels will make the steering wheel wobble,out of balance rear wheels will cause the rear of the car to wobble, and this is usually noticable between 50-80 mph,

hope this helps, and welcome to FF !

I have had all 4 wheels balanced and they would wobble all the time at certain speeds if it was a balance problem, the wobble only occurs under acceleration.

Certainly looks transmission related with drive shafts looking the most likely suspects but always worth checking the real easy stuff first.

Have you actually transposed the front and back wheels ?

Thanks for the response.

The wheels have been changed around but it has made no difference.

I also think its transmission related, a mechanic has checked the cv joints and they are ok, he says there is a bit of movement in one of the driveshafts but his opinion is that its not enough to cause the wobble.

So far:-
the tyres have been changed and balanced.
engine mounts checked.
cv joints checked.
Its 4 years old and only done 39,000mls

What else could be checked?

when you get vibration under load its normally one of two things, either a tyre out of shape, this normally occurs when the tyre is warm and goes out of shape, its a good idea to get your tyres inspected after a run. BUT the most likely cause is a driveshaft, this is normally possible to diagnose by driving the car on a ramp, but with the lower arm supported so the driveshaft works in its correct range. If your lucky you will be able to see or feel the faulty shaft under load. Good luck

If driveshafts are of unequal length, the longer one is sometimes fitted with a balance weight...which has been known to fall off.

Don’t know if this applies to the stilo but once had a Renault with the same fault, it turned out to be the inner drive shaft joint (gearbox end).
If you can find an empty car park drive slowly on first one lock then the other, if the front of the car feels like it’s going up and down it’s the inner joint.
Most garages don’t check the inner joints.

Thanks for your replies, it gives me something to look into.

A bit of an 'off the wall' suggestion (I'd certainly endorse the suggestions made in previous posts) but I experienced something similar with my JTD. Although not as bad as you it would seem.... I'm not saying it's the answer but could be worth checking out.

It might be worth getting your garage to look at the state of the bushes in the front suspension arms - although the bushes don't come seperately and you need to replace the whole arm - as the bushes in mine (particularly NSF) were pretty much shagged out.
Before changing them the car felt like it was 'scrabbling' for traction but this wasn't immediately obvious through the steering. An unusual and not entirely pleasant sensation.

Hope you get to the bottom of the problem.

I've spoken to a FIAT mechanic and he said if it vibrates under load it's the tripod bearing on the drive shaft(s).

Mine vibrates but not really any worse under load and definately doesn't stop when dipping the clutch.

When bushes go on the arms you get an annoying knocking noise over an uneven road surface.

I've replaced front shocks, arms, disks pads, the drop links are fine the rack is fine, the wheel bearings are fine and the d*mn thing still vibrates

Gonna try the drive shaft bearings next.

My abarth has just gone to the Fiat service with the same problem and they suspect one of the driveshafts has broken. Not cheap

I have at last had the "wobble" problem sorted, it was a damaged differential.

The stilo drives soo much better but the repairs cost me a fortune, wish it had been a driveshaft fault it would have been a cheaper fix.

Thanks to everyone who tried to help in finding the problem

Thanks for posting the 'result' - really appreciated