Leaking diff output shaft

[Simonpfhc]

Hi all,

I finished rebuilding my FHC last spring and have had some glorious drives over the summer. I’ve put about 1000 miiles on it now and the only real issue is a leaking rear seal around one of the output shafts on the diff. This then leaks down on to the disc and preserves the pads forever. Oh, and then theres the issue of no braking on that corner!

Anyway, I dropped the IRS yesterday and have removed the offending flange assembly for a closer inspection (it had a full rebuild before fitting). It looks as though the surface of the flange that the seal rubs against has suffered from age/use. There is a ring if pitting which is obviously letting oil through.

The item in question is item 36 in the pic below:



Great picture thanks to SNG However, not surprisingly, NLA.

So, I’m looking for some advice as to what my options are.......

Cheers.

[mgcjag]

Hi Simon......contact Alan Slawson at http://www.ajsengineering.com/Services.html well known to the forum and normaly at Stonleigh for jag spares day... if he cant help then you are in trouble....Steve

[Simonpfhc]

Good call Steve, thanks.

[kingzetts]

Simon,

You may well be right about the source of your leak. There is another possibility you should consider, and that is oil leaking down the splines between items 26 and 36. These splines need to be sealed with some gasket sealant on assembly to prevent this. Alan Slawson rebuilt my diff last year after I despaired of solving exactly what you describe despite changing the oil seal thrice, and he said this leakage along the splines had been the cause of my leak.

This leak path only exists on 3.8 cars. Jaguar eliminated this leak path on later (4.2 onwards) cars when they changed the design of the output flanges to place the retaining nut inside the flange housing.

[Simonpfhc]

Hi John,

Yes, after posting I did spot and read you comments in other threads. Indeed, there is a large amout of oil on the splines, so it could be the culprit. I would imagine that if everything fit and sealed as it was meant to, the splines (outer end at least) should he bone dry.

I will be ringing AJS as Steve suggested to get their opinion and will feedback when I make some progress.

Cheers.

[Simonpfhc]

Ok, spoke to Alan Slawson today from AJS Engineering. What a knowledgable and helpful guy.

So after discussing the issue of the oil leak, these are the three things that should remedy the problem completely:

1. The pitting on the machined surface that the seal runs against could indeed be allowing oil past. This can be helped by using very fine emery cloth to re-polish the surface.
2. The actual seal can be pressed further into the housing by 1 or 2mm. There is enough room for this and will result in the lip of the seal to run against fresh metal.
3. Apply a thin smear of sealant onto the splines of the output shaft. He suggested to use Wellseal or even thread lock.

He finally reminded me to always fit a new O-ring where the unit bolts into the diff.

I’ve orderd a new seal, O-ring and brake pads so should have it all back on the car for the weekend. Once fitted, will report back with the verdict.

Cheers.

[abowie]

1. The pitting on the machined surface that the seal runs against could indeed be allowing oil past. This can be helped by using very fine emery cloth to re-polish the surface.

Cheers.

Why not just fit a Speedi Sleeve and a new seal?

[Simonpfhc]

That looks like a good solution Andrew. I’ve never heard of these so will investigate.

Cheers.

[abowie]

I use them a lot. Cheap and effective.