Not much of an intro to this one. The diff pinion oil seal wears out from all the trips to Tesco's, and replacing one is not too bad - with the exception of the flange centre nut, which 99% of the time requires explosives to get undone. Method of replacing the seal is the same as any other L/R - the nut and it's tightness varies though, and you should make sure that the method/torque wrench setting is correct for you axle.
Signs of the oil seal failing is what you would expect - yet another pool of oil on the drive, a quick check underneath will confirm -



Raise the drivers side wheel and put an axle stand under the axle. There's plenty of room around the rear prop/axle to get at all the bolts, so apply hand brake. The prop is held to the flange by 4 x 14mm head nuts/bolts, so propshaft tool and 14mm spanner.



Once all 4 are removed - cable tie the prop out of the way. The flange centre nut can now be seen. This is the early castellated nut and split pin type - later models have a nyloc nut.



The axle case has to be drained, and there's a square key bolt almost at the bottom - a 1/2 drive extension bar with no socket fits just nicely. Clean around the drain plug and then remove it.



The flange centre nut is very tight, a breaker bar was neede to undo it. Retrieve the washer, and the flange will then just slide off the pinion shaft.



The reason this seal failed was because it had been renewed incorrectly. This type of seal has to be fitted with the raised centre level, or slightly below the axle casting. Whoever fitted it just put it so that the edge was level with the casting - the result was that the drive flange wrecked the seal.
The diff pinion oil seal has an inner and outer lip - each with it's own retainer/tensioner. This was all that was left of the outer one.




Raised outer lip on the new seal - this has to be level or slightly lower than the axle casting.



The inner lip - again with it's own retainer ring.



Clean the axle case and then tap/press the new seal in the correct amount.



Re-assemble the flange according to your axle/nut type, and re-attach the prop. Replace the drain plug and then fill the axle case with the correct amount of fresh EP80/90 oil.


Les.

Dont forget to check the seal track on the diff flange for wear , This is usually the most common cause of seal failure along with blocked axle breathers .

These are really handy HOWTOs Les. The relatively simple LR jobs that come up again and again.

Les, correct me if I am wrong, but if you remove the flange nut is there not likelihood of needing to re set pinion height/backlash/mesh?

Indeed, depending on your L/R. Rebuilding the diff assembly would have to be a different thread, as it's a lot more work, and quite complex. If you had excessive play in the pinion/crownwheel mesh before replacing the seal, then you will still have it after doing this.


Les.

Hi Landmannnn,

This excellent post by Les is for the 'rover' type diff fitted to the front and rear axles of all SWB series landrovers, 90s, Discos and Rangerovers. It also applies to the front 'rover' axles on all LWB series landrovers and 110s. It differs slightly in relation to the Salisbury rear axle fitted to LWB series from late series 11a or to the rear salisbury fitted to 110s(and any very rare salisbury front axles).

The difference between the two types is that the 'rover' type diff has the pinion bearing preload set by shims, whereas the salisbury axle has the pinion bearings preload set by a crushable spacer.
What this means is that providing you have no play, you can change the rover pinion seal without worrying about upsetting the pinion bearing preload. With the salisbury axle, providing you have no play in the bearings, you can still change the seal, but you should very carefully mark the pinion shaft and nut before undoing them to make sure that when you reassemble them, the same amount of preload is applied to the bearings. If you tighten the pinion nut too far, you could put too much preload on the bearings by crushing the spacer between the bearings too much.

Hope this helps,
Regards,
Diff

Les, do you have the Rover part number for that pinion seal? I have never seen the double lip/spring pinion seal in Australia and I am looking for a more effective seal because my upside down rear diff really floods the normal pinion seal.
Bill.

Bill :-

Rover Number is FRC4586 - 'Oil seal for pinion'

If you have Bearmach over there, then their number is BR0668


Les.

Thanks Les. Their is a BM agent over here.
regards Bill.

Paddocks website shows that part number for Series and RR upto 1985, wish I'd known this before I changed mine yesterday as it looks better than the FRC8220.

Richard

Could anyone explain how you would do this for a 3 bolt disco diff with the bar sticking out of the middle please.

Brougham