Thump in drivetrain at low speed

[chucky083]

I have a V8 VY Calais. 4sp Auto.

At very low speeds just as i accelerate from standing or if im coasting in heavy traffic i get a thump that feels like its between gearbox and diff. It seems to be irregular (not in time with engine/gearbox speed) and never occurs above ~10km/h. It happens in both drive and reverse.

Has anyone else experienced this?
Is there any likely suspects to check out?
Or is this just a design flaw with the gearbox being clunky between neutral and drive/reverse?

[danja]

Is it happening just as you step on/off the accelerator?

[jesse3.8]

+1 for this

[madgamer2006]

this happens on my vy executive as well... any help would be great

[DUK13Y]

Sounds like it could be this:

Common vy diff fault

[simmyz1]

this sounds like a prob i had with my wagon and it ended up being spark plug leads, believe it or not!, local mech said it was common problem as a faulty lead caused a miss which, to me , sounded like a diff or tranny thump.. hope this helps

[red truck]

If it's a heavy dull thud could be broken engine mount. Mine was doing it from time to time.
Confirmed it by blipping throttle at walking pace, really makes it thump.

[Bazzdogs]

it can just be a general looseness in gears. Getting movement from the motor all the way to the drive wheels requires alot of linkages and gears. between each gear might be maybe a millimetre or two of slack, not much. Add all these gears and slackness together and you got yourself a big gap which needs to be taken up by force from the motor. Thats what i was told, my first gear is so low tuned i can physically get a smooth drive in traffic without disengaging the clutch. if i speed up in first i always get several big jolts cause it almost throws it self forward which puts more slack in the gears.

[vt s]

Pop your bonnet get someone to stand at side of car while your inside.
Put in drive, hold foot on brake and just quickly and lightly blip the throttle.
This will find if its your engine mounts or something else.