Final drive pinion oil seal 1971


I like the idea of punched alignment marks for re-assembly due to simplicity, but the accuracy of that method assumes a constant correlation between the torque applied to the nut and the force required to turn the pinion. What has come out of this useful debate is that that assumption may not be correct. Friction at the oil seal lip is one variable; another is bearing wear. Hopefully (not a strong basis on which to proceed!) the wide range of permissible pinion turning force will accommodate these variables.

Given that the consequences of error may lead to a second differential rebuild, I am tending towards adding an accurate digital torque screwdriver to my kit and following the manual procedure.

I will post a conclusion when done.

Thanks for all you input.


(Dick Maury) #43

The friction from the oil seal is negligible with the new rubber seals. In the old days with leather seals, they did require a bit of effort until broken in. Usually the setup on the early cars is without the seal in place to get the right amount of shims. Once determined, the diff can be assembled with the seal. The turning torque spec in the book is for new bearings. It is also for the pinion alone, not the whole diff with carrier and axle torque. Setting up a broken in diff with the spec for new bearings will result in bearing failure in short order. In assembly with a new or used diff, the turning torque is the critical factor, not how much torque it takes to tighten the nut. I have a impact gun that puts out 1000 lb/ft of torque and sometimes it strains to tighten the nut enough to crush the crush sleeve. On a broken in diff using a crush sleeve, mark the nut relative to the threaded shaft and put back in the same position. The earlier XKE’s (1968 and back) are much easier as they use shims that do not change with nut torque. Also, the nut torque does not change the backlash. This is determined by the shim spacing under the inner pinion bearing race. If you have preload on the bearings as you should, more torque or preload is not going to move the pinion. This procedure gets a bit easier after you do a few thousand of them.

(Rob Reilly) #44

For Frank, my manual is publication E.172/1 covering XJ12 and dated 1972.
I should have asked Frankie for the date of his.

It is interesting that, while mine, presumably written by Jaguar engineers, stresses their view that the pinion seal cannot be changed without going through the whole disassembly/reassembly routine in 90 steps; his, also presumably written by Jaguar engineers, takes the view that the pinion seal can be changed by the turning torque method described.

For Dick, my 1950 Mark V has a leather seal on the pinion. For that one, the changing procedure is quite simple, though not relevant to this discussion, in that the nut is slotted with a cotter pin, so you tighten it snug (no torque specified), then back it off until you can get the cotter pin in. But of course there is quite a lot in that manual about measuring backlash.

(Paul Wigton) #45

The marking technique is what I used for diffs using a crush sleeve, and never had a failure, due to incorrect torque.

My Rover uses a separate nut, to set the crush sleeve, and the u-joint flange is just a slip-on, over splines, so replacing the seal is an easy, fast job.

(Frank Andersen) #46

When everything else fails, Frankie - read the manual…:slight_smile:

Given that the original bearing lash was set correctly, the ‘mark and set’ is a valid option. Bearing also in mind that it’s necessary to ensure that the nut must be on the ‘correct turn’ - assessed by release torque reading or turn counting…

However, the advantage of following the workshop manual’s procedure is that you verify actual bearing lash - for good or evil…

If the lash is too tight; replacing only the seal likely wont do much good anyway…

xj6 85 Sov Europe (UK/NZ)

xj6 85 Sov Europe (UK/NZ


Mine is “Service Manual Jaguar XJ6 Series 1 2.8 litre & 4.2 litre” publication No E.155/3 with a 1972 print copyright date.

The first section in “Final Drive Unit” deals with the early differentials, the second section deals with the collapsible spacer differentials. The final page is the one I uploaded and describes the procedure to “Remove and Refit” the oil seal. There is no comparable page in the first section - so I assume this procedure was introduced with the collapsible spacer diffs. The total section on final drive is 19 pages of technical text (excl indices and titles).



Thanks Dick - I appreciate your follow-up.

The manual section I was referring to is specifically for “remove and refit” of the seal - presumably therefore with a broken-in diff. I assumed that the turning torque figures given there included an allowance for bearing wear. Having said that my bearings have only covered about 3,000 miles from new since the last rebuild.

Nevertheless, good to know that the marked alignment method is valid and well tested in practice.


(Phil Dooley) #49

Timely thread.

During the last oil change, the tech was kind enough to let me look under the XJ6 for leaks, and it appears that the front pinion is leaking after 35 years and 60,000 miles. There was so much congealed grease on the diff that I couldn’t readily tell if the side plates were leaking too, so I hired a mobile detailing service to degrease and pressure wash the underside of the Jag, including the IRS and diff.
Will have to observe for a few days and see if it is pinion seal, side covers or both that are leaking.

With the optimistic assumption that it is just the pinion leaking, I asked two reputable shops how much they would charge to replace the pinion seal.

The first shop wanted 2.5hrs of labor plus parts. He said he’d measure the running torque before removing the yoke, install the seal then torque to spec and measure the running torque again.

The second shop does a lot of diff work and I’ve used them in the past for a rebuild of a Jag diff (not this car). He quoted me about an hour of labor plus parts. He said, however, it is usually a fool’s errand to replace the pinion bearing because the bearing is often worn or loose and it will take out the seal again in fairly short order. He’d do it without a guarantee of the work. He does a lot of Dana diffs, but just a handful of Jags (His recommendation was to pull the diff and rebuild it - $350 + plus parts)

The technique to successfully restore the preload with a seal change notwithstanding, what’s the success in stemming the leak with a pinion seal change? Is the one mechanic correct that the seal will be just a temporary fix, or does heat from the inboard brakes cook them till they leak and I can get by for another 60K miles with a pinion seal change?

I’m leaning towards having the pinion seal replaced for the hour labor plus parts and rolling the dice on having stopped the leak.


(tony) #50

I dont believe it would be possible for a pro to pull a Jag IRS, remove the diff, and rebuild it for $350. That would assume he could do the whole job for ~4hrs labor, and not spend a penny on parts.

The output shafts in the Jag diff have 2 bearings each, which need to be replaced, along with the seal, which is on the very outside. Those parts alone are worth over $100. Then there would be the diff bearings themselves, and pinion seal (assuming he would replace the bearings, and not re-use them)

On solid axle D44 that would be a good price

  • edit…I see you said $350 PLUS parts…that would be a great price if it is firm

(Pete55Tbird) #51

Phil, if the Dana 44 was in a Jeep rather than a Jag do you think you might get different opinions
on replacing a leaking pinion seal? Why not try? Pete

(Frank Andersen) #52

If preload is tested and at spec before seal replacement, Phil - it implies normal bearing function, and no specific increased seal wear. The heat from the inboard brakes play little part - the diff gets very hot without their help…:slight_smile:

Theoretically; the bearing play can be reset, at some risk, by increasing torque for further sleeve crushing. But it implies some bearing wear - which may require a more comprehensive diff overhaul…

I would simply replace the seal - and see what happens; it is one of those sleeping dogs - to be woken at need…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

(slofut) #53

Ten minute job to replace the seal. Mark the position of the nut well (not so easy) and DO NOT use your impact gun to “run the nut up close” and then hand tighten into position! Don’t ask me how I know.

So yes, replacing the seal is straightforward and easy enough, putting the nut back where it was is not.

(Phil Dooley) #54

Thanks very much for your collective advice. I’m going to go ahead and replace the pinion seal and see what happens - it is worth a shot for $100, guarantee or no.

As far as the overhaul of the diff - his quote was based on the diff out of the car. There’s a spare 2.88 diff kicking around in my shop and my intention was to have him build my spare diff and I’d R&R the IRS to keep the downtime reasonable.

For him to take the diff out of the car and replace it after the diff was overhauled would be another 9.6 hours of labor on top of the 3.5 hours to setup the diff after replacing the seals.

I suspect that if I were to let him do the whole job, I’d have a bill for north of $2000 for parts and labor.

Rear Diff Seal Series II