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Discussion Starter #1
Hi All,
I have a problem with a leaking rear axle/half shaft seal. I have had this seal replaced but it still seems to be leaking. I suppose the replacement seal may be the wrong one or a dud, but when I looked down the tube this is what I saw. The round area at the diff end of the tube seems to be flattened off in the 4 - 6 o'clock position. Could this be contributing to the leak? What exactly is this structure ? !
Thanks,
 

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Oil retainer

Hi Richard,
I did not have the correct parts book handy, but one I did have might call that thing an oil retainer? To me, however, it looks to be the remains of the outer oil seal! Not good. Someone hammered it IN past the lip until it just slid down the tube:eek:. It appears to be laying against the back of the outer carrier race. The flat is where it was pried with a screwdriver to get it out before that someone just pounded it in:confused:. This will be a pain to get out without pulling the differential:mad:. My guess is that you may have to do this anyway as the seal seat, or the sealing surface on the half shaft may be damaged by the degree of force required to get the original seal there to begin with. :eek::mad::mad:
Is the sealing surface on the half shaft Ok? No scratches burrs or damage? How about what you can see of the seal seat? Pry marks perhaps? Maybe from a screwdriver? Edge of the seat burred?
Worse case, pull the rear axle, pick up a used outer tube if the seal seat is history, possibly a half shaft if that's bad too, then... put it all back together correctly, new bearing and seal. Lots of labor to repair someone's idea of a quick fix.:(
I hope I am wrong, perhaps someone else may see it differently, as this is just my opinion. :DGordon Raymond
 

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Richard,
I think what you are looking at is the differential bevel pinion shaft through what is left of the oil seal. Normally from the diff side of the half shaft out, is an inner half shaft bearing, a shim, the oil seal, a pinion shaft nut, a locking plate holding that lot and finally an outer half shaft bearing. With the half shaft removed, as in your picture, you should look directly down on a circular oil seal which in your case (as Gordon said above) has been forcibly rammed in and bent. The only way I can see of fixing the problem is to replace the axle tube on that side as you've got no guarantee that even if you manage to extract the stuffed seal, the inner sealing surface of the axle tube is not also damaged. Hopefully your half shaft should be OK - check the outer surface and the splined end for obvious damage - they are pretty tough :)
I sincerely hope you get back on the road again. Let us know how you get on.
Regards,
Chris
 

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I've added a picture of the standard half shaft setup. Hope it helps.
The numbered bits are -

54 Inner bearing
73 Shim
64 Oil seal
67 Shaft nut
68 Locking plate
63 Outer bearing
66 Spacer

Chris
 

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Well Richard, Chris and I agree, and he is working from the same diagram as I. As one that has built a bunch of these, the face of the seal #64, is now, unfortunately, down by #63, the bearing shim. Your ACTUAL LEAK is probably from either the damaged seal seat, or a messed up area on the half shaft sealing area. I too am interested how this all works out. Be sure to keep us informed. Photo's are good, as they will help others as well. Gordon Raymond
 

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Discussion Starter #6
Still puzzled

Gordon/Chris,
Thanks for the input guys. Your theory certainly sounded very reasonable and I thought you had cracked it. I haven't yet checked the shaft but I thought I would pull out the halfshaft from a spare diff I have lying in my shed and take another photo. Lo and behold :eek:
Now, the affected diff is in my '68 1750 but is from a 2000 berlina. It came from a totally different part of the country from the spare which I think is a 1750 diff. Exactly the same appearance!
It would be unlikely for the same rogue mechanic or dubious technique to have been used on both diffs ?
Is this then the normal appearance? Does anyone else have their diff apart/halfshaft out at the moment for a photo?
Cheers,
 

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Ain't that interesting. As far as I know, all of the bits are at least symmetrical, if not circular, though I must admit that I've never looked down the tube after replacing the bearings. Does your spare diff leak oil?
What did Sherlock Holmes say about odd events - once you've eliminated the impossible, whatever remains, however improbable, must be the truth - or something like that.
I'll be interested to see other peoples' photos.
Regards,
Chris
 

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Over the last couple of hours I've talked to a mate of mine who has owned many more Alfas than I have over the years. Between us we were trying to remember what happens when you pull out a half shaft. From our collective memories we think that the oil seal usually comes out on the shaft - that is, you don't pick it out of the axle tube. It is replaced on the half shaft before you gently reinsert the shaft into the axle tube and seat it home on the splines. Maybe what you are looking at is the shim and inner bearing and not an oil seal at all. In that case even if diff oil gets past it, the seal should still prevent it from leaking out.
What came out when you removed the half shaft? Is the stuff that is leaking out oil or maybe brake fluid from a leaking caliper? I'm just guessing now, so maybe it's time I went to bed and slept on it :confused:
 

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The Answer!

Now this is getting interesting! ALMOST tempted to pull one apart and have a look. Almost... After fiddling with these cars for 40+ years, I must admit I have never looked down a tube. If things ware bad, I pulled the whole axle assembly, and took it all apart, repaired as required and reassembled. I honestly do not remember if the back side of the carrier bearing looks like that... BUT, I DO KNOW WHO DOES:cool:! He is working on one as I write this;)! PM Alfar7, Richard Jemison. He is currently building this type assembly for one of his customers. He can read this thread and either answer from memory or better, be persuaded to include photo's:rolleyes:! Ask him to have a shot at this one! :DGordon Raymond
 

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Dixrex: I'm can't really resolve what I'm seeing in your photos. Something looks weird (those flat areas at 4 O'clock, the shape of the seal face), but it's tough to really see what's going on.

Chris1750 had written: "From our collective memories we think that the oil seal usually comes out on the shaft - that is, you don't pick it out of the axle tube."

Chris: My memory tells me something different: I believe that the seal remains in the axle tube when you pull the half shaft. Perhaps you're thinking of the FRONT seal, which does come off the hub when you remove the hub, since the inner bearing is usually stuck on the spindle.

Gordon Raymond had written: "Worse case, pull the rear axle, pick up a used outer tube if the seal seat is history"

I agree, but remember that if it's the LEFT axle tube that is damaged, the operation becomes more complicated. The left side - the side with the larger diameter flange - contains the bearing that supports the ring gear & differential. That bearing has been shimmed to provide the correct side-to-side clearance. It is unlikely that mixing a used axle tube with your old differential and housing will produce the correct dimension.

If your left tube is bad, it would be more practical to install a complete, used differential assembly than to fool around with re-shimming the bearing.
 

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Jay,
You are no doubt right - it's been a while since I've pulled out a pair of half shafts, though I distinctly remember that the job went very smoothly. My mate is still convinced that the last set he did, the seal came out with the shaft - maybe they were so rooted that they would have fallen out anyway. A bit like skinning cats I guess.
I might get him to sign up to the BB so he can argue his case directly rather than using me as an intermediary.
None of this has yet answered the original questions - what are we looking at down the end of that axle tube, is it normal and if so, why is oil leaking out?
Back to the forge,
Chris
 

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Discussion Starter #12
Maybe what you are looking at is the shim and inner bearing and not an oil seal at all. In that case even if diff oil gets past it, the seal should still prevent it from leaking out.
What came out when you removed the half shaft? Is the stuff that is leaking out oil or maybe brake fluid from a leaking caliper?
Chris, I suspect you are right about the inner bearing. The seal stays in the tube and is reasonably difficult to remove, requiring a moderate amount of force with some adjustable pliers to get it out (haven't got a seal puller). I'm pretty sure it's diff oil - there was oil outside the seal when I pulled the half shaft and there is no fluid leaking from the disconnected brake caliper.

I took the opposite half shaft out of the spare diff today and have attached the photo. Same appearance without the flattened off area. Perhaps this is due to wear?

Gordon, I will pm Alfar7 - perhaps he can sign this off!

Jay, It is the right half shaft that is giving the problem.

Cheers,
 

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Richard Jemison
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Tube Thingy

There is one in all axle tubes. Early cars relied on diff lube for there lubrication. Later cars did not as the bearings were sealed. But
there is a drain back through all of them somewhere.

They are there to contain the lube to some degree in the center diff as the car is cornered. otherwise the oil would head for the end of the tube.

The retainers in Alfa`s are "thingys".:p Remarkably the hole in the center is larger by far than the early axles themselves. Most racecars use a true "seal" to keep the oil in the differential.

If your car is leaking at that side you can pull the axle out and 1st inspect the axle shaft at the seal area for wear/damage. Good time to replace the bearing if any wear is evident. If it is loose it could be a contributor.

These cars also need to be checked for play in the bearing race area laterally. If you can pull & push on the brake/backplate assembly and get in & out movement, you need to shim between the retainer plate and outer bearing race to end that. As Gordon found the retaining snap ring used to hold syncroniser assemblies together works perfectly. (I have a few a few laying in the trans parts cabinet if needed) They work perfectly as they can be sprung to the side a bit to get over the axle without having to press all the bearings etc. off. ;)
To the seal. Pull the one in out:p and check the outer seal surface. clean it up, wipe in a bit of RTV (Ultra Blue is impervious to most gearlubes) and install the seal carefully.
You need to lube the seal and not destroy it installing the axle.
if all mentioned above is good it won`t leak.
Rj
 

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You need to lube the seal and not destroy it installing the axle.
This is an extremely important installation tip! Do not allow the weight of the axle to rest on the seal as the axle slides in. Unless of course one likes changing axle seals every week.
 

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Discussion Starter #15
Oil retainer !

Thanks Richard and Jim.
I have checked the half shaft today and it looks fine. Will get a new seal and install as per your instructions. I'll also check the outer bearing and half shaft in/out play. Will update when it's back on the road.
Many thanks for everyones' help.
Cheers,
 
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