Diff input seal

Good morning to all,

I recently changed my (non leaking) pinion input seal on my Sulisbury Power Lock differential when I had the IRS down just to be on the safe side.

Well, now it leaks…

Jaguarclassic gives the part n°: AEU1685J no longer available and nowhere to be found…

Instead I used the seal from the XJ40, n°: CBC6923 that is supposed to be the same.

While fitting all seemed well, correct dimensions and identical shape with the old one…
Did I do something wrong ??

Any advice would be welcome.
Thank you,

Arrgh … never touch a running system;-) But you probably found out about this one yourself;-)

Sad to hear, but from what you describe I can’t see anything wrong except maybe the sealant: what did you use?

As for the seal itself: is it this one https://www.sngbarratt.com/uk/#!/English/parts/34c78886-4320-42d7-9715-0e8c5afb2d82. At least they don’t state it has been superseded.

Good luck


75 XJ6L 4.2 auto (UK spec)

I got round to filling my solid D axle (modified Mk2) I was dismayed to see a slight leak. The guy who installed my 4.10 Powr-Lok, instead of the open 3.54 he’d chosen, was a pro and I’d assumed he had good technique.

It had not run since building and I figured maybe the bare steel flange seal track had corroded in damp air. I used tissues and cotton buds with carb cleaner but the seal lip area seemed dry although drips were running a few per day slowly from the input seal down to the drain plug. Best I can tell there’s a nick or mark or swarf between seal case and diff casting at about 7 o’clock. Lots of carb cleaner, some ‘right stuff’ black rubber gasket maker in the tiny crack and all is well. I fitted a big breather to keep it that way

Hi Aristides - I wonder if the surface prep on the running surface is part of the issue. I don’t have much experience on this, but a search of the interweb indicates that it’s a thing.

Try searching “elastomer seal running surface finish” or similar to get an idea.


When I replaced an original leather seal on my 420G, just ordered one off Ebay,
(from a known supplier)…they show the 2 different types

the good news is it isnt hard to do this from under the car

sounds like you checked the seal surface

maybe just a dud seal

the one I fitted was dual lipped

Ordered a new seal, this time from a different supplier, installed it and all seems to be fine.

The new seal was somewhat different, brown colour (Viton?) instead of black, harder material and with a much tighter fit on the shaft.


I had a leak at the back of my BW12 - after a professional rebuild. I guess the apprentice fitted the seal. I was a single lip - the type that might come with a kit. A year later I replaced it with a double lip seal and some Hylomar (or similar) at the housing - job done. Paul

“ain’t broke, don’t fix it” Carl

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what was required to allow access to the seal in terms of removing the yoke and any other parts ?

Drain the diff, unbolt the driveshaft from the flange and you have access to the pinion nut.
The yoke might be mounted with sealant so an extractor might be needed, mine was not and pulled right out.
Be sure to mark the position of the pinion nut so you can put it back at the same place exactly and not mess the pinion bearings preload.

It was a better and easier job than I expected. About 45 minutes and I had the yoke behind the tranny in my hand. Mindful that everything had been removed in the recent past - no frozen nuts/bolts. The 1 1/2" nut came free with a couple of hits from the rattle gun. Paul

I did drop the rear mounting - maintained the box in place with trusty floor jack. I didn’t upset any if the positioning on the mounting and all went straight back in. Just pulled the forward section of the tailshaft back and to one side, enough access to get the R and R the seal.

… till it is!