2003 Doblo 1.9 JTD

The Symptoms:

Moderate to severe wobble/shake on acceleration in all gears from about 1500 RPM upwards. Particularly apparent in 2nd & 3rd gears, but if I put my foot down in any gear the shake will result until I ease back on the accelerator.

No wobble whatsoever when coasting out of gear at any speed, (or with clutch depressed). No wobble when stationary at any revs, so hopefully not clutch or DMF.

Wobble felt through seats, floor, but not really through the steering wheel or gearstick. FEELS like it's coming from the front of the van but it's hard to say. Also difficult to say whether the wobble is side to side or front to back etc. I estimate that the shake oscillates at 4 to 6 pulses a second. It's not pleasant!

Wobble happens only when accelerating straight ahead or turning left (worst). No wobble at all when turning to the right. So joining roundabouts I get a wobble, while on the roundabout no wobble, when I turn off roundabout the wobble resumes.

The greater the load (eg uphill) the more severe the wobble.

The only way I can get the wobble to lessen (though it's still there) is to carry a passenger (or presumably a heavy sack of something) in the cab with me. The added weight on that side of the front of the van seems to quell the shaking. Or to accelerate very slowly through the gears. Or just go round clockwise circles.

Steering, braking and general handling otherwise seem normal. There's no visible play in the steering, and that's not where you feel the wobble anyway.

The engine pulls like a train so I don't think it's the problem. The gearbox had new bearings and diff gears last year, and the gearbox guys who did the work don't think the problem lies in the box.

When sitting on axle stands, and the wheels driven, the wobble can still be felt (though fainter) so I'm suspecting that it's not a problem from the rear axle. Obviously the load is less when the wheels are dangling in the air.


Things I've tried so far...

Wheels (original steel) and tyres all thoroughly checked, tested, balanced. Tracking checked. All wheels inflated and tightened correctly.

All four wheel bearings are quiet with no free play or noise when the wheels are spun and shaken top/bottom, forward/back, and side-to-side.

More than one garage has inspected all visible suspension/steering bushes, joints, links etc and can find no wear. Crowbars have been applied to wishbones to check for free play.

Top and bottom gearbox mounts have been changed.

N/S driveshaft inner CV tripod joint replaced by independent Fiat specialist. When this didn't help, I got an entire new driveshaft fitted on the O/S. No improvement. So both inner CV joints are new. The van turns in tight circles in both directions, backwards and in reverse with no clicks or knocks from the CV joint area.

As I say the only thing that seems to help is when I'm carrying a weight in the passenger seat. I guess that if this was LHD, I wouldn't have a problem!

No one I've spoken to seems to think that the shock absorbers are likely the cause, and there are no nasty squeaks when I bounce the corners. It did occur to me that the upper suspension mountings or shocker bushes may be the culprits, but would they be capable of causing the shake/wobble?

In wet weather (and only when I'm traveling passenger-less) I sometimes get a metallic click or tap coming from the passenger footwell area when I step on and off the accelerator. This may or may not be related to the wobble. I hoped that the new lower gearbox mount would cure this, but a drive today in the rain confirms it's still there.

The gearbox people say they don't think that the problems in the diff as the wobble's there when accelerating straight ahead. The best they could suggest was to try replacing the N/S driveshaft completely, though as I say the inner CV joint is new. I think they were stumped.

The van passed its MOT back in December with no advisories (the wobble was evident at that stage and I had a local garage inspect the front underside prior to the MOT test).

Sooooo...

If anyone has managed to take all of this info in, and has any idea where I should investigate next, please chime in and I'll try to get this van back on the straight and narrow. I'm concerned that the shake will get worse and result in catastrophe.

Likewise, if anyone can recommend a good logical thinking intelligent motor mechanic (in or around NW London) who might be able to troubleshoot the problem, my ears are very much open.

Thank you very much for reading this!