Firstly a bit of background. My car is a 1989 TVR Wedge 400SX (that's the supercharged 4 litre model).
The jag diff on the wedge is fitted as standard equipment. It's a 3.31 ratio PL.
I've had the car for about 10 years and done 85k miles. The car weighs 1100kg so load through the diff is limited by rear end traction ;^)

The diff is fitted on a cradle in a similar way to the XJS and has the standard Jag inboard disc brakes.
The suspension arrangement is a bit different however. It's still IRS and there's a lower wishbone, but the top link is via the driveshaft (a big chunky one) that keeps the hub and wheel in a parallel plane to the brake disc as it were. So the output bearings of the diff form part of the suspension.

If you are all cool with this and giving me some advice please read on...

I have been trying to track down the source of a noise and my investigations led me to the diff output bearings.

"A whirring noise that starts at about 20mph and whirs according to road speed.

Knocking it out of gear so the engine is idle doesn't change the noise (except it gets slower again).

The whirring noise disappeared when cornering left"

I have now removed the diff on its cradle stripped off the calipers and removed the output bearings, and they don't particularly feel grindy or flapping around loose, although one feels tighter to turn than the other. Should they turn effortlessly and silently or is some whispering OK? While I have the diff out I suppose there's nothing to lose by changing the bearings, will they need pressing in/out etc?

The front bearing shows a bit or end float, maybe as much as a millimetre, and if I press on it while turning I get a noise from the diff internals, so I wonder if that's the problem, well it seems to be a problem anyway. As I recall the front bearing is the technically more difficult one to replace? It also leaks so the seal needs doing.

The crown wheel teeth look in good nick except for a small chip on the very corner of one, but it seems far away from where the pinion should engage so probably not an issue.

Please give me advice on:

- good places to get parts (I see some timken stuff on fleabay)
- rebuilding the side bearings
- replacing the front oil seal and possible the front bearings

As you might understand being a TVR owner of long standing I am well used to a bit of spannering!

P.S. For a little Jag connection/kudos, one of my best friends used to own Terry Wogan's old burgundy XJS....

 

Ward Engineering in Colchester are the guys to go to for all jag diff parts and rebuilds. The driveshaft setup doubling as the top wishbone link you have is standard Jaguar, by the way. That noise is failing diff noise, that is for sure, I would rebuild it entirely. The endfloat on the pinion shaft is not right, thee should not be any, but you cannot just tighten it up, there is a crushable washer fitted to get the correct loading.

 

Thanks I've emailed them for a price list.
I have seen salisbury beraing sets for LR diffs on fleabay in the £100-is mark.

When replacing the front oil seal doesn't the crush washer have to be renewed anyway?
If so maybe doing that will sort out the end float issue, and possibly the output bearings are relatively easy to replace. Do they need pressing in/out or can you freeze the bearing shell to get it in?

I heard tell there were also crush washers in the output bearing assemblies it this true?

= Adam

 

Regarding the pinion end float, is there anything wrong with this technique?

Differential Pinion Pre-Load Adjustment.

although it goes against your advice of not tightening the nut... but the logic seems sound. If the crush sleeve/preload isn't too tight, you can do up the nut. If it's too tight, you can't undo the nut, you have to start with a new sleeve.

In my case, wear over time has left it a bit loose, so presumably I can tighten the nut incrementally to restore preload.

​​​​​​​

 

This seems to be a useful thread:

https://www.jaguarforums.com/forum/x...d-noise-11556/

incidentally I have been replying to my own thread but nothing comes up - what gives?

 

Greg - thanks for the reply - have emailed Ward for a parts list.

I found a post elsewhere (bernardembden.com) about tweaking up the pinion nut to remove end float - says if you do it gradually to meet the crush sleeve then you can take up the slack. Just make sure to check the preload is within spec each time before tightening further. Sounds logical to me. If you exceed the preload that's when you have to dismantle and replace with a new crush sleeve.

Seems like "quick replies" work OK...

 

I tried it once and it just made things worse! Not saying it cannot be done; just saying it is basically a matter of luck, IMO. But the noises on cornering indicate to me a rebuild is necessary, regardless of the pinion situation.

 

Yeah I wish I had found out about the pinion end float before fropping the diff, could ahve tried this while still on the car and possibly saved myself a big job.
Never mind I can do a few other things whlle it's off.

I think I have come up with an explanation for the thing going quiet while cornering left = if the pinion bearing is also slightly sloppy, the propshaft will tend to push to the right (Newton't law) which will press the pinion back onto the crownwheel a bit, removing the play. As it tightens on the roller bearings it will also retract slightly.

So - the noise might be nothing to do with the side output bearings at all, but nevertheless they now seem fairly simple to replace so why not do them and the seals while they are out.

I think I'll take a punt at doing the pinion myself as a rebuild will cost a fair amount and I can have the diff back on the car to test relatively easily (that is, seal, outer bearing check/change, nip back up). Another option would be to pick up a second hand diff which are around £200-£400 depending.

 

I have been given a recommendation for a rebuilder in St Neots so I may find out how much they charge.

In the mean time I was thinking - the noise disappearing on cornering left - that can only be a good sign? Presumably if the diff is reset back to the "sweet spot" there's still a reasonable chance the noise or at least consequent failure problems will go away?

One advantage of the Wedge is that the exhaust is so flaming loud it masks minor whining etc, also my gearbox is hardly silent, so I can put up with minor whining as long as there's no massive vibration - the drivers seat being pretty much over the diff. Also with the supercharger, the intake noise is 103dB(A), which helps too ;^)

 

Progress has been good.

I have dismantled the diff and removed the front bearings, as even by eye there appeared to be asymmetric wear on the rear (inner) pinion bearing. I am wondering if this is related to the layout on the TVR where the gearbox output is on the centre line but the input to the diff is offset?

As Ward haven't come back to me yet I have researched bearings and equivalents, from Timken and SKF. looks like about £35 for a front set, and another £20 or so for seals, thrust washer etc so maybe £60 all told. A bit cheaper than £350-£450 I have seen for rebuilds!

Any preferences for bearing manufacturers?

Also any tips on removing the bearing inner from the pinion shaft (I was thinking of trying heat - pouring boiling water over it quickly to make it expand might free it up quickly)?

I'll need a new spacer washer 0.82mm = 0.032" as the old one got a bit mangled in the shell extraction.