356a rear axle seal problem (leak)

[Paul Thompson]

Hi guys,

I'm in need of some help from the braintrust here. Just finishing up putting all new brakes/lines on my 57 speedster and noticed I had a decent leak at what appeared to be the axle seal on the right rear. So, I took everything apart, replaced said seal along with the 2 o-rings, installing everything as it had come out and low and behold I still had a leak! I then broke out the trusty Elfrink book (should have done that before!) and realized that there was a procedure for measuring the gap between backing plate and bearing cover to ensure you have the correct shim size. Assuming this was my problem, I tore it all apart again, measured as per the book and indeed my gap was too large. I put everything back together with the now correct shims, and within 5 minutes or less of filling the transaxle with new fluid (Swepco), I had fluid leaking out. It appears to be leaking from within the splines - see pic below. Any thoughts as to what I may have screwed up?!?

[Curt Dansby]

Hi Paul
When you put the larger o'ring over the bearing it rolls so there is a twist placed in its normal orientation. After you get the o'ring up to the bearing housing put a small bent pick under the o'ring and rotate it around the bearing a couple of times to get the twist out of it. It will pull back some from the housing, just carefully slide it back flush without rolling it over the bearing.

Curt

[Martin Benade]

I agree that the oring would be the source of that leak. Also inspect for nicks in the areas that the oring seals on.

[Paul Thompson]

Thanks guys. Curt, yes I did notice the oring twist a bit putting it on originally and I thought I had it corrected, but perhaps I did not. Ugh...maybe third time's a charm! Fingers crossed...looks like I'm going back in.

[Eric McKinley]

I did this job on both sides a few years back after one side was leaking just like yours.

If I am not mistaken the large O ring can also get nipped during tightening.

[Paul Thompson]

UPDATE: So, I had another seal kit lying around so disassembled everything and put it back together with new o-rings. I couldn’t see any obvious issues with the o-rings upon removal but I reassembled and the leak is MUCH better than before, however still there. It probably takes a good 10-15 mins now for a drop to form but you can still visually see leakage at the splines. I noticed the spacer that seats against the small o-ring looked pitted, so I’ll order a new one and another seal kit and hope that does it. Thanks all for the advice, will update again soon.

Paul

[Jon Bunin]

Paul,

This has nothing to do with the large o-ring, it is leaking past the small o-ring.
If you have not yet installed the brake drum and torqued the rear axle nut, then the newly installed small o-ring will not seal effectively.

[Paul Thompson]

Ahh, I see...thanks Jon. Yes, I figured it had to be the small o-ring, but I did not realize that the drum and axle nut was necessary to achieve proper crush on the ring....perhaps I have no problem then, as it is now barely seeping out with no drum installed.

[Rick Johnson]

In my search for a solution to a rear axle oil leak on my 59A coupe, I found this thread and decided to post in it rather than start another. After removing the rear backing plates and installing new seal kits I have a leak on one side between the backing plate and the axel tube flange. I removed the bearing cover to check the large o-ring and it looked fine so I reinstalled the bearing cap and torqued to 42 ft lbs and it is still leaking. My question is will this leak go away after the brake drum is installed and torqued or do I have another problem? Thanks in advance for any help on this!
Rick

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[Vic Skirmants]

Torquing the drum will have no effect on that leak. It has to be the O-ring. Can you post photos of what you have dis-assembled?
One tip on installing that cover: I install a stud in one of the bolt holes to help line things up. After installing three of the bolts, remove the stud.
This also helps immensely if you are doing the work with the parking brake cable in place.

[Rick Johnson]

Thanks Vic! Appreciate your response and installation tip as I did leave the parking brake cable attached to the backing plate. I'll take photos when I remove the cover and post them if the leak continues after reassembly.
Regards,
Rick

[Rick Johnson]

Finally got out to my shop to see the results from using Vic's installation tip. Thankfully the leak has stopped. For anyone else having issues installing the brake backing plate and bearing cover I recommend disconnecting the parking brake cable and using a stud for alignment and then removing the stud after you have the 3 other bolts installed in the bearing cover. This makes it so much easier to keep the backing plate, O-ring and bearing cover in the correct orientation.

Thanks again Vic for sharing your knowledge!

Rick

[Vic Skirmants]

Using the stud method, you don't really need to disconnect the parking brake cable.
Glad to help. Also glad some people follow my advice.

[Wes Bender]

I think more people follow your advice, Vic. They're just not thoughtful enough to let us know about it.