Diff Output Shaft Leaks

[kingzetts]

I know the diff output shaft seals are prone to leaking. On my car I have replaced the output shaft seals at least 3 times in the last 7 years but each time they continue to leak - enough to worry me and drip off the edge of the brake discs in small amounts, not enough apparently to fail an MOT.

Anyway, I'm fed up with this and will try once more this winter to sort this out. On the basis that simply replacing the seals doesn't work (and yes, I am sure I am doing it correctly, and I have each time also replaced the o-rings in the output bearing housings) I'm looking for ideas.

I am wondering if the output shafts are sufficiently worn to not quite seal adequately, although visually they do not appear so. Or if oil leaks down the splines on the output shaft and past the big fat washer under the nut which holds the flange on the shaft.

Ideas welcome, but also I am wondering if the best approach is to have the diff thoroughly checked and repaired as needed by a specialist - in which case any recommendations for Salisbury diff specialists?

Thanks in advance for ideas.

[Heuer]

Is the diff breather clear? On my FHC I had a diff seal leak and found some Muppet had painted over the breather valve with black POR15. Once I had cleaned it the seals no longer leaked - basically it was a pressure increase in the diff housing as everything got hot. The valve is really odd and very difficult to see if it is blocked, unless painted over, obviously

[kingzetts]

Hi David, yes the breather is clear - I fitted a new one last time round and checked its efficacy by blowing compressed air in via the fill plug!

Neither the input shaft nor the diff rear cover are leaking, it's definitely the output shafts/seals and/or bearing housings.

[cactusman]

Mine leaked. I had a jag man do mine. the output shafts were worn. Hence the lack of sealing. One was replaced and one was sleeved. I did not do the work so no pics sadly but I do have a very large bill!!! A year one and no leaks.......yet!!!!!!

[kingzetts]

Who did you use, Julian?

[rfs1957]

Must be those roads we shared.

My diff was overhauled in 2014 I think - whenever I last posted about diffs anyway ! - and I had assumed that was a fit-and-forget, problem passed onto the next generation.

Apparently not ; I've got the two symmetrical drips now too, shiny calipers etc and identical spray patterns on the roof above the diff. If it had just been one side I'd have assumed I had cocked something up, but both ?

So am mighty relieved to hear that I am not alone and I shall be very interested to hear how you proceed. I found AJS extremely helpful, can't remember the chap's name but he posted me some unobtanium shims from his magic box for free, and when I saw his handwriting I realised héd done the diff on my car in the late 80's as I recognised it from a long forgotten invoice.

No, it's not my breather either ..........

[kingzetts]

Heeding Einstein's (I think) dictum that insanity is repeating an action expecting a different outcome, I shall this time not attempt to solve the problem myself after 3 previous failed attempts. I'm in contact with AJS and will most likely send him my diff in November or so for sorting. I will report back in due course.......

[cactusman]

Sorry Kingzetts....been on hols. I used a local garage but I rekon you would be too far away....I see you have found an alternative. Sure they will sort you out.

[ETTony]

I have my diff out to fix a couple of leaks. Rear seal and drive shaft.
The replacement seal is rubber part #8436A* an alternative to the leather that I expected.

Are we all fitting these new improved seals now ?

[rfs1957]

Anyone else faced with these issues, and have any of the combattants made any progress since the last posts ?

Kingzetts ?

I'm reluctant to pull the IRS apart again to change the output seals again without knowing WHY my last repair failed. Was there a duff batch of seals ? Mine would have been SNGB.

[kingzetts]

I had mine overhauled by Alan Slawson last autumn. It has not leaked in the 2500 miles since. He reckoned the key was to put sealant on the splines of the output shafts over which the output flange fits, as oil does leak down those splines and past the nut and washer which holds the flanges onto the output shafts and is mistaken for leaks from the seals.

I believe this only applies to the earlier diffs where the output flange is separate from the output shafts. Later diffs I think have a different arrangement and lack this particular leak path.

[mgcjag]

Hi Rory....twice on my S2 i have changed the output seals and its still leaking...the first time i replaced the bearings as a matter of course when refurbing the irs.....after discussing with Alan it seams that the original bearings for my diff are no longer available and all the replacements dont seal to the oil seal correct....i got replacement xjs output shafts and seals as a unit from Alan that he assures me will solve the problem just need to drop the irs again....anyway on to your problem.....you need to identify exactly what type of diff you have..there were 3 types just for the S2.....then contact Alan and discuss with photos to show him what you have....he "knows his onions" i assume thats a French saying All the best.. Steve
http://www.ajsengineering.com/index.html

[rfs1957]

Thanks for those observations, will bear all that in mind when next in pieces. Something tells me that my half shafts are NOT of the type where the output flanges are splined into the shaft, but rather one-piece, so the splined-routing of the leak would not be possible. Unfortunately ....... it would be easier to fix.

[kingzetts]

Has your diff been changed, then, Rory? Your car is a few months older than mine (Nov 1962) so I'd have thought we would both have had the early type diff originally.

[mgcjag]

Hi John...arnt they all basically the same anyway...a shaft with a flang and bolts at one end, a smooth section for the oil seal bearings etc and a splined section......so a one piece splined shaft.....then a carrier of different types for the seal and bearings... Steve

[kingzetts]

Steve, not so I'm afraid.

On early diffs like mine, the output shafts have two splined sections - an inner section which engages with the diff internals, and an outer section which pokes out beyond the bearing housing and terminates in a threaded end. The output flange then attaches from the outside and has inner splines which locate over the outer flanged action of the shaft and is retained by a large nut and washer on the end of the output shaft. The oil seal bears on the outside of the hollow shaft of the flange. There is therefore an oil leak path down the splines and past the nut and washer.

On those diffs the output flanges can be removed from outside the diff without first removing the bearing housing from the diff.

Later diffs have the output flange and the output shaft combined into a single component. The only flanged section on this shaft projects internally into the diff. The oil seal bears on the outside of the shaft. The output flanges cannot be removed separately from the shafts, which requires removal of the bearing housings from the diff. Because of the different design there is no leak path down the flanged section as the flanges are entirely internal to the diff.

Compare the diagrams on plates 18 and 19 in this extract from the 4.2 parts catalogue from our knowledge base. Plate 18 shows the earlier design with output shafts with both an inner and an outer flanged section and an output shaft flange which slides onto the outer flange section (as on my car). Plate 19 shows the later design where the flange and the output shaft are one component, the outer flanged section has gone and only the inner flanged section remains.

https://dl.dropboxusercontent.com/conte ... /file?dl=1

I believe the entire assembly of bearing housing and output shaft from later diffs can be fitted to earlier diffs if required.

[mgcjag]

Hi John..thanks for the detailed explanation.....didnt realise there was an o/p shaft with splines at both ends, but then ive not really looked at the S1 diffs.....on my S2 its different again to the 2 versions you discribe and there are different 3 types..anyway Alan really is the guy to talk to as you mentioned so long as you can tell him exactly what you have....problem is its such a pain if you have a leak replace the seals and the leaks still there.. Steve