Rear Differential (GKN??)

[jaydev]

Hello Folks,
I have just had my rear differential rebuilt and the mechanic is asking me about the oil to refill it with. In the handbook it says ep90, but he reckons that as its LSD it will need some special oil of some sort.

Any Ideas?
Many thanks for all your help

Jaydev

By the way, the car has had the gearvendors overdrive fitted, gearbox reuilt and the rear subframe and all components are being rebuilt. Will post some pictures soon!! exciting times!

V12 Coupe 1990 H Registered

[Brakebuster]

ALL XJS diffs are LSD , some with ' powerlok '

as an LSD EP90 will be fine, and you can add some LSD additive before your fill with oil

diffs were either Salisbury or Dana , depending on supply issues to the factory when your car was assembled ,

Salisbury diffs have the rear filler plug to the back cover plate


bring on the pics......


BB

[jaydev]

Many thanks BB

Tried to upload the pics but its not working. Will try again later

[PaulGover]

FWIW, Morris's do a Limited Slip Diff oil with built-in additive, at a very reasonable price. I haven't done enough miles to say if it's any better or worse than say Castrol plus additive, but I like their 10W40 that I use in the V12's engine. See here for mail order, or ask your local motor factor.

[llewy007]

Hi,
I have a 1991 facelift 4.0 coupe and the rear diff is starting to seep oil. Are there any torque wrench settings related to the diff, pinion nut for example?

[davidr]

Sounds like you have a weeping pinion seal? Changing it yourself with the diff in situ is possible but you need to be clear what you're doing. It's not a case of replacing the seal and tightening the nut to a specified torque. There is a crushable tube inside which will have been nipped up just enough to set the pinion and crown wheel at the right relationship to give the correct backlash.
The trick is to get the nut back on to EXACTLY the same position as it was. Any difference will make the backlash wrong and increase noise and wear.
The method I use is to first mark the position of the nut to the pinion shaft (using a dot punch) and then carefully count the number of revolutions to take the nut off.
When replacing you just need to count the number of revolutions to put the nut back on and realign the marks.

[poprivet]

I changed mine a while ago, I did learn a few things though:

Drain the diff oil first,
Removing the tie plate gives better access for re-filling,
The pinion nut was damn tight to undo,
The new seal needs to be pushed in tight to seal using stag or similar sealant. You need something baked bean can sized, but a lot stronger, (yes, I did initially try using a baked been tin but it crushed completely without seating the seal!)
Refilling the diff is damn messy unless you have an access hole in the boot bulkhead,
There are now plenty of LSD 80-90 gear oils to choose from, the purists say only use Shell Spirax with a bottle of additive but that was the recommendation 30 years ago, LSDs are far more common now.

Complete success by the way

[llewy007]

Many thanks!

I have passed on this advice to my mechanic and have my fingers crossed!