Differential (final drive unit) rear cover gasket

[Mephistopheles]

My E Type has a non-original differential with GKN casting mark on the housing and with final drive ratio 2,88 :1. I assume that it is a differential from an XJS, although the rear cover is not made of aluminium and has no cooling fins. It looks like shown in the E Type Series III parts catalogue.
There is oil sludge on the differential around the rear cover, otherwise the housing is dry everywhere.
I therefore want to replace the cover gasket.
Does anyone know if the differential cover gasket (part no. 3931) in E SIII parts catalogue fits GKN differentials?
Is it possible to replace the cover gasket (drain oil, unscrew lower cradle plate, loosen rear cover screws, ...) without having 100 joints on your fingers and hands, or will this little gasket require IRS removal?
Best regards

[lowact]

How do you know it is 2.88, could it be 3.07, I think these were GKN? Are there tags on the diff?
I note that 3931 is the only differential cover gasket that SNGB sell’s, suitable for 45 car types. So, if yr diff has 10 bolt holes, this gasket should fit 'cos no other choice?
Can’t imagine why you might need to drop the IRS just to replace the cover. However, with the cradle lower plate removed, check carefully for signs that leakage from the shaft seals may have flown back to collect around the edges of the cover. Also look at adjacent surfaces around the (3) shaft seals, where leaking oil may have been flung by the centrifugal force.
If the diff has never previously been refurbished, imo the seals will almost certainly be hardened, if not perished and cracked. Otherwise, a leaking seal may be indicative of a worn bearing.

[mgcjag]

The diff cover cannot be totally removed whilst the diff is in the irs.. however you can undo it and maneuver it enough to fit a new gasket...Steve

[Mephistopheles]

Gentlemen, thanks for the confirmation; I had already thought that replacing the gasket would be a fiddly job. It is indeed a 2.88 differential, because a corresponding tag labelled "2.88" is attached and a recalculation (certain speeds -measured with GPS- at different revs) has led to confirmation. In the XJS spare parts catalogue I also found out that the cover gasket of the GKN differential actually has the same part number as the cover gasket in the E S III spare parts catalogue.
Regards
Holger

[angelw]

Holger Wrote:

In the XJS spare parts catalogue I also found out that the cover gasket of the GKN differential actually has the same part number as the cover gasket in the E S III spare parts catalogue.

Hello Holger,
Or you could do as I and many others do and that is to make a new gasket out of superior material as that supplied by various vendors.

It's rather common to see the flange of the cover deformed at the bolt locations due to excessive tightening of the bolts. If this is the case with yours, the flange should be planished back into shape before assembly with a new gasket, and of course, avoid over tightening the bolts.

Regards,

Bill

[Mephistopheles]

Hello Bill,
Thanks for the advice. I plan to coat the paper gasket with a thin layer of Hylomar blue on both sides, I have had good experiences with this, especially if the sealing surfaces are not in perfect condition.
What kind of superior gasket material are you using to make the gasket?
Best regards
Holger

[angelw]

Holger Wrote:

What kind of superior gasket material are you using to make the gasket?

Hello Holger,
Superior as in thicker than what is normally supplied for this application; accordingly. there are a lot of material types to pick from.

It goes without saying to use some form of gasket dressing, but often the flange is so deformed by prior by over tightening of the bolts that a good seal is not achieved, even with the use of gasket dressing, if the flange is not plannished flat before use.

Regards,

Bill