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Leak free tranny - possible

As mentioned before, and since I do not agree with the theory that oil leakage from a gearbox is a normal and acceptable thing (I have a BMW designed in those years and it is spotless),
when I overhauled my gearbox all bearing facing outward were replaced with the sealed type, when the inward sealings were removed.
I also used shamelessly modern rubber oil retainers where necessary. ​
I do remember that there is one oil seal or oil retainer somewhere in the depths of the bike made of felt (?), Which before assembling I soaked it, as much as possible, in heavy industrial grease.
So far the box is not leaking at all.

email (option): michasteinmann@gmail.com

Re: Leak free tranny - possible

I agree Michael....If it's possible to 'improve' on the original specification in a discreet way it seems crazy not to and it is possible to reduce or eliminate much of the leakage that was inherent in the original design...

We use Gel batteries, electronic regulators, anti wet sumping valves, led light fittings, modern brake lining materials and clutch plates etc....Why should the approach to oil leaks be any different?....Ian

email (option): ian@wright52.plus.com

Re: Leak free tranny - possible

Michael, you mention a felt oil retainer. Is that the felt piece inside the chaincase?

Re: Leak free tranny - possible

No, no; I'm really sorry but I do not remember.
Yes, there is also a large felt gasket in the chain case and I also soaked it in grease, but I vaguely remember that there was a non-metallic bushing on one of the shafts inside the box.
Sorry.
Maybe I'm mistaken here.

I remember that at the time of the dismantling, due to age and dirt, it initially looked to me like the rest of the bronze bushings, until I noticed its low weight relative to others and checked what it was made of.
And I also remember ordering it from DraganFly.

email (option): michasteinmann@gmail.com

Re: Leak free tranny - possible

OK Michael, thanks.
PS what BMW?

Re: Leak free tranny - possible

There's a tapered felt washer that slides over the gearbox mainshaft and seats against the outer end of the sleeve gear...The gear and its internal bush are countersunk at the end to accept the tapered side of the felt washer...Ian

email (option): ian@wright52.plus.com

Re: Leak free tranny - possible

As Ian said. No61 in the diagram. Ron
ScanC

Re: Leak free tranny - possible

Even then you still have the starter and the gearchange to leak oil from
And I really can not see how the gearchange can become leak free , unlike the unit boxes you just can't machine a square depression & slip a quadring in there .
The other problem is the absence of any breathing for the gear box so sealing them up tight will lead to other problems.
The original design can breathe through the scroll

Re: Leak free tranny - possible

Hi Ian
I managed to locate quite a number of these tapered felt seals some time ago
I will be using them in my gearbox rebuilds coming up
I have some spare if anyone needs them
Correct type & shape are generally not available
Jo’b

email (option): jonnyob1@googlemail.com

Re: Leak free tranny - possible

I'll have a couple John....Ian

email (option): ian@wright52.plus.com

Re: Leak free tranny - possible

Save me a couple too if poss John. I'll see you at Kempton. Ron

Re: Leak free tranny - possible

Hi, for the models A7 A10 and B31 B33 there is a sprocket nut with an oil seal (SRM). Why not for "our" BSA ?😭

John 👍

email (option): john.kater@chello.nl

Re: Leak free tranny - possible

Michael, you mention using sealed bearings but removing the inner facing seals. I can understand this with the gear change end of the main shaft to allow pass through of oil. My hand change gearbox does not have any holes to allow oil to pass from the outer case to the main body so requires oil to pass through the bearing. So in this instance both seals need to be removed.
Would it not be better to leave the seals on the main bearing at the drive end in place since these bearings are intended to be maintenance free for their life.
Regards, Lionel

email (option): Lioneljrudd@gmail.com

Re: Leak free tranny - possible

Bob
OK Michael, thanks.
PS what BMW?
R51

email (option): michasteinmann@gmail.com

Re: Leak free tranny - possible

Lionel Rudd
Michael, you mention using sealed bearings but removing the inner facing seals. I can understand this with the gear change end of the main shaft to allow pass through of oil. My hand change gearbox does not have any holes to allow oil to pass from the outer case to the main body so requires oil to pass through the bearing. So in this instance both seals need to be removed.
Would it not be better to leave the seals on the main bearing at the drive end in place since these bearings are intended to be maintenance free for their life.
Regards, Lionel
There is conflicting debate over that Lionel. On the one hand, you remove the inner seal so as to lubricate the bearing in the normal manner. On the other hand as the bearings are sealed for life and you wouldn't remove a seal for a wheel bearing application. Why not leave them intact which would protect them from debris and double the sealing effect against oil leaks?? Ron

Re: Leak free tranny - possible

I was advised to remove the inner seal as the gearbox oil serves to both lubricate and crucially, cool the gearbox main bearing...The advice came from a friend who was the chief development engineer at RHP bearings (as well as a BSA enthusiast) so I decided to go with that...It's worked so far...As the bearing at the gear change end is entirely within the gearbox the presence of seals would serve no purpose in preventing leaks....Ian

email (option): ian@wright52.plus.com

Re: Leak free tranny - possible

Yes Ian I have always removed the inner seal, but I can't help thinking...Is it necessary? There was often a problem with Wiilys Jeep gearboxes where the oil would pump from the gearbox into the transfer box through the open mainshaft bearing. The fix was/is a sealed bearing and the one I bought had steel seals on both sides and the instruction was, to leave them intact. I also think that wheel bearings work harder than a gearbox main bearing and possibly get just as hot??? Ron

Re: Leak free tranny - possible

These are questions that don't have an answer...You would have to do a long term road test under similar conditions with both set ups to determine definitively which method is best in terms of gearbox bearing service life, so we'll never have the true answer I suspect...

The purpose of the modification is to reduce/stop oil leaks through the bearing and having a single seal fitted seems to achieve that OK...
Removing the inner seal gives the bearing lubrication in the way that was originally intended and IMO there seems no logical reason to change that if early bearing failure is not an issue...

At the end of the day I suppose everyone must pick the theory they prefer...Ian

email (option): ian@wright52.plus.com

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