Transmission Clonk!

[daveyb]

I have an odd clonk from my auto box when reverse is selected. There is no noise when I reverse when the car has been standing, but when warm I get this clonk.

To try and find the problem I have had the sump pan off, fluid spot on clean, replaced sieve filter and no nasties on the magnets. Put fresh fluid in still the same. Other than the clonk when warm it works perfectly.

Anyone got any ideas

[steve455]

Hi Dave, the only thing I can think of is the transmission mount. The various rubber parts fall to bits and allow lots of movement. You should only be able to push the back of the gearbox up an inch or two. If its bouncing around a lot with the torque twist of going into reverse ????? worth a look.

Check the driveshaft nuts and UJ's while you are underneath and look for splits in your rubber coupling onto the diff (can't remember if your year has this) for splitting between the bolt holes.

regards

Steve

[daveyb]

Thanks for that Steve

I will get underneath and have a good poke around. Got the perfect excuse now to go and hide in the garage as my wife has decided to put her ‘Little House on the Prairie’ DVD on!!!!

[MARKPEARSON]

Hello daveyb
If you decide to change the gearbox mount foam buffer ring buy a genuine Jaguar one it may save you doing the job twice like I did when I fitted an aftermarket unit first.
Best Regards Mark.

[daveyb]

Hi Mark

I will go down the genuine Jaguar route, as I have been having a good poke around the underside and the anti-roll bar bushes are looking a bit squashed and may also need replacing.

I have heard that aftermarket ones don’t last as long and using those polly-bush types around the car totally ruins the smoothness but doing the steering is ok with them?

Regards

Dave

[steveww]

I replaced the steering bushes with the poly type and there is a small amount of extra vibration through the steering wheel over pot holes, drain covers etc. On the positive side the steering is more accurate. I stayed with standard Jaguar bushes every where else on the suspension.

[MARKPEARSON]

I have noticed polybush do these kits in three types,kits performance dynamic and comfort has any one tried any of these I would my self be more interested in the comfort variety.
Best Regards Mark.

[ng4xjs]

I’ve decided to bite the bullet and replace the diff on my car. It doesn’t look like a major job albeit I don’t possess sufficiently high axle stands or a trolley jack with sufficient lift. So I thought I’d do the sums and find out how much it would cost the lazy way.

I tracked down a firm in Suffolk who would recon my diff for £430 which seemed reasonable. However my local friendly Independent Jaguar Specialist wanted £750 to drop the cage and put it back. Blimey.

Has anyone else done this on an outboard set up recently using just the ordinary home garage equipment and how did you get on? Any thoughts suggestions or otherwise greatly appreciated.

Happy Days
Nick

[dhdove]

Nick

Vince (Brake Buster) removed his (inboard disc set-up) diff cage in his garage with the usual "home" tools and got on OK. Why don't you drop him a pm?

Hope all is well with you

TonyS

[almcl]

Nick

I replaced the rear axle cage on my SIII XJ (same as a pre-facelift XJS) a little while back. I have no special tools, just a normal pair of axle stands and a 2 ton trolley jack.

Jack up under the tie plate and insert axle stands under the jacking points. I then inserted a block or two of wood between the jack saddle and tie plate and jacked again, increasing the height of the stands.

The really time consuming bit was disconnecting the exhaust pipes, although eventually an air chisel helped separate the joints. Getting the radius arms off at the front was too much of a challenge, so I undid the rear ends.

After dropping the cage, using the trolley jack, I was able to extract the cage sideways. This meant that the car didn't need to be very high up.

I actually swapped one cage for another (which I had rebuilt in slow time) all told, working slowly by myself it took about 3 days.

[ng4xjs]

Thanks Guys - I'll have a go.

Nick

[kelsham]

Might be worth checking the bolts that hold the diff in the cage before spending money. They sometimes come loose giving the symptoms you describe.

Regards kels.