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Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 8:18 am
by pwhodkinson
Thanks for useful site.
Some help please. Just doing the rear oil seals on my 1976 1300. And I've crawled the web, manuals, YouTube.
Getting very conflicting input.
My question. The big o-ring that sits around the wheel bearing. Does it go inside (closer to brake backplate) or outside (closer to wheel) of the paper gasket?
Thx


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Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 9:26 am
by Donovan D
Image

Hope that helps

Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 10:15 am
by pwhodkinson
thanks. hmm. all the manuals have pic like this. But then see some impressive looking youtubes from guys who seem to know what they are doing saying they stick the oring outside paper - which kind of makes sense as there is a notch/ groove in the bearing cover casing.
would explain why mine continues to leak despite what i thought was a meticuluos job if i got it wrong (o-ring closer inside).

Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 10:32 am
by 73type2
As per the diagram, the o-ring goes around the bearing. I had oil leaks in the past after doing this job and found that the o-ring got jammed because I didn't make sure that it got seated in the groove on the casing. If you follow the diagram correctly and slowly you won't have any oil leaks. I use a bit of rubber grease when installing o-rings.

Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 10:36 am
by Donovan D
https://www.youtube.com/watch?v=j0TxH4NCGUE

Have a look at that video, use a bit of grease to ensure the o-ring stays in place before fitting the cover.

Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 10:50 am
by pwhodkinson
thankyou both. And yes I have seen this video - he wants to put big O-ring on the outside of the paper gasket (unlike the diagram). Yet if you look in the comments to his video even you will see people disputing this!

Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 12:36 pm
by Tony Z
I recently did a custom rear disc conversion and I also had the O-ring and paper gasket.
I havent put oil in the gearbox yet, so the rest of what I say could be completely wrong.
I cant remember if the manuals I had showed the gasket or not.
But, as you rightly point out, the gasket either fits on top of or behind the O-ring. In my opinion this effectively defeats the purpose of the O-ring. I mocked this up numerous times and nothing made sense. So I resorted to first principles in my thinking.
The inner O-ring and shaft seal should stop oil coming out of the shaft so they stop it leaking there.
The outer seal or O-ring stop oil coming out from around the periphery of the housing so they stop it leaking there. In all honesty, I think if anything, the gaskets we are getting today are supplied with the hole being too small. The O-ring should do the sealing. My conclusion is that we should be able to use the O-ring by itself and not worry about the gasket.
Also, you take it one step further - the housing holds the rear bearing in place. Those gaskets are pretty thick and this holds the bearing cover away from the point where I have measure that it should sit, and this will allow the bearing to walk a little (even if it is 0.3mm).

I might be wrong and would be very happy for someone to tell me why. It might also be nice if someone else tries this too and confirms whether the O-ring is good enough all by itself.

Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 1:11 pm
by pwhodkinson
Great response Tony! Glad to know I'm not the only one theorizing about it! I have thought the same that without the paper could work too.Or even cutting the hole bigger on the paper.
I was thinking of doing one wheel inside, other out to test. but now you add third option of toss paper!
Not such a fun job that I want any to fail though!

Re: Rear wheel bearing o-ring

Posted: Tue Jun 26, 2018 6:27 pm
by retrovan
pwhodkinson wrote: Tue Jun 26, 2018 1:11 pm Great response Tony! Glad to know I'm not the only one theorizing about it! I have thought the same that without the paper could work too.Or even cutting the hole bigger on the paper.
I was thinking of doing one wheel inside, other out to test. but now you add third option of toss paper!
Not such a fun job that I want any to fail though!
Tony is correct, the oem paper is bigger holed and has nothing to do with the "O" ring, they should not be in contact with each other as this will compromise the seal. and the location of all the parts., also the paper will collapse and create a path for a leak.

You are safe to cut the paper hole bigger and assemble as per drawing.

Herman