gearbox clonk on pulling away

[dennisv8]

My car is a 1999 with 138,000 miles, still on the original engine and gearbox. Over the last couple of months an annoying clonk with accompanying lurch happens when pulling away after coming to a halt. This doesn't happen every time, just enough to be annoying, but will it get worse ? I have had the gearbox flushed through and filled with new oil and had a new filter etc. but this hasn't really made much difference. Does anyone have any suggestions as to how this can be cured or will I ultimately have to have a new or recon gearbox ?
By the way I'm a fairly new member and this is my first post !

[mike020150]

Hi Dennis,
Welcome to the bulletin board. Noises, including clunks, are notoriously difficult to diagnose without seeing the car. In your case, if there are no other symptoms, like roughness of changes or other strange behaviour, I would be inclined to look for a problem in one of the engine/gearbox mounts or even an exhaust mounting before planning a gearbox change. If there is such an issue with a mounting, it will probably be accompanied by marks on the underside of the car where something like the propshaft is able to touch the underside of the car periodically. Good luck with the search. Mike.

[MyQuest]

I used to own a 1999 XK8 which 'clunked' on pull-away. Looking through the paperwork I noted that in 2000 it had been listed as a possible warranty item by Jaguar - who decreed that it was 'slight play in the differential' and deemed not a worry...

I ran the car from 2004 till 2010 and it became no worse. It's now running around in Holland and still going strong..!

Michael

[J44EAG]

Also check the gearbox to propshaft dough nut. These have a habit of breaking up.

2 x 17mm or 19mm spanners needed to remove and replace if that unit is on its last legs. A straight forward job if that is all the fault is.

Mike K

[dennisv8]

Thank you for all your replies, they have put my mind at rest that I'll not need a new 'box. Will investigate the other possible causes.

[painter]

Had the same on my 96 coupe, after much investigation diagnosed as diff - which I could live with, but now a vibration @ 70 (ish) which I cannot. If you do need another diff. 'XJK' up north are a very good resource for 2nd hand ones (new diffs are rare and £1000 + vat before fitting).