2010 Fiat Ducato x250 2.3L Turbo Diesel


When accelerating between 80-110 kph the vehicle shakes. The vehicle is completely fine below 80 kph and above 110 kph. The strength of the shaking is directly proportional to the torque applied. As an example, cruising between 80-100 barely pressing the gas the shimmy is almost imperceptible. Accelerating on even ground it's noticeable but not horribly bad, however the greater the incline and the harder I press the pedal the worse it gets. So hard acceleration up a steep hill between 80-110 feels like the van will shake itself apart.


Tie rod ends are fine. The shimmy is felt in the entire vehicle and is very violent going uphill at hard acceleration, it's not felt just in the steering wheel.


Recent work done on the vehicle:


Replaced a torn outer CV boot on driver's side front axle. Noticed there is a little in / out play perpendicular to the vehicle's body. There is no such in/out play on the passenger side axle.


All four tires balanced and new hubs / bearings / discs on rear axle.

Hi Sailorbob

To try and narrow this fault down:

It is related to road speed irrespective of which gear is selected, i.e. not engine speed related. That tends to rule out an engine power delivery problem or something to do with the clutch and flywheel.

It occurs over a relatively small speed range. 80 to 110 kph corresponds to 11 to 15 wheel revolutions per second, giving a fairly low vibration (shaking) frequency of 11 to 15 Hz. The small range suggests a resonance effect.

It's related to the drive torque. That rules out unbalanced wheels/tyres as the cause, as they give vibration which is only related to road speed, not torque. However, in my experience the vibration frequency for a Ducato with unbalanced wheels (due to the mass of the wheel in conjunction with the suspension spring) is around 16 Hz and occurs around 115 kph. This a similar frequency to what I think you are experiencing, so points towards the front wheels and suspension area.


I suspect you have a torque-dependent drivetrain movement problem which is exciting a vibration in the front wheels similar to that caused by an out of balance wheel.


I suggest you check (in order of likelihood):

Both the driveshafts and their joints and bearings.
The front suspension wishbone bushes
The engine mountings (which resist the drive torque to the wheels).
The output bearings of the gearbox
The final drive gearing


It might be possible to fit a camera under the vehicle to make a video recording of what's going on, but I suspect that the amount of unwanted play/movement might be too small to see unless the effect is severe.

CV joints, inner or outer may cause the problem. Often overlooked is the intermediate bearing and housing on the long ( drivers side on a RHD) drive shaft.

Mike

So the in / out play in the driver's side axle doesn't necessarily indicate that the axle is the problem? I assume when you say driveshaft you are indicating the axles? Is there something else to check on them other than looseness in various planes, i.e. in/out play, up/ down play?

Hi again

In the UK, we normally call the shafts that transmit power to the front wheels "Drive Shafts". Other countries may call them "Axles". But we are talking about the same thing.

Each drive shaft has a constant velocity (CV) joint at the inner end, and another at the wheel end.


The inner joints are designed to allow a bit of in and out movement, because the effective length of the drive shaft has to change a little bit as the road wheel moves up and down with the suspension. The inner joint should have no play up and down or forward and back.


The outer joint should have no play in ANY direction, so in and out movement here could be a sign of wear.

I suggest you get the shafts/axles checked by someone who is experienced in front wheel drive vehicles, and can therefore easily recognise what is normal and what is faulty.

You may be able to replace the joint, rather than change to whole axle.

So after reading this section in my book Automotive Service 3rd Ed. by Tim Gilles I replaced the driver's side axle and the problem went away.

I suspect that when I recently changed the outer dust boot I may have damaged the inner tripod joint. Usually when I change an outer dust boot, I undo the inner dust boot and slide it out so I don't have to drain the transmission. Then I remove the inner joint to slide the boot up onto the outer joint. When I went to remove the inner tripod joint it was so loose that it actually when I removed the circlip it just fell off...
If I have time I'll inspect the old axle and see if I can verify anything and update this answer.