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Thread Like Summary
Z900
Total Likes: 5
Original Post (Thread Starter)
#850756 06/05/2021 10:22 AM
by Z900
Z900
Hi, i'm investigating the oil-leakage from the gearbox.

Got the gearbox out and I saw oil comming out the seal of the main output with the gearbox leaning on the shaft (after 2 / 3 min)

1. Is this OK ? (I think no)
2. When I rotate de sprocket, the seal is turning in the case, is this correct ?

Thanks, Gerrit

https://i.gyazo.com/328bc137ead51f8af286362fb7253b06.jpg
Liked Replies
#850762 Jun 5th a 11:36 AM
by kommando
kommando
Originally Posted by Z900
Hi, I'm investigating the oil-leakage from the gearbox.

Got the gearbox out and I saw oil coming out the seal of the main output with the gearbox leaning on the shaft (after 2 / 3 min)

1. Is this OK ? (I think no)
2. When I rotate de sprocket, the seal is turning in the case, is this correct ?

Thanks, Gerrit

https://i.gyazo.com/328bc137ead51f8af286362fb7253b06.jpg

1. No is correct

2. The seal should not rotate in the case.

For 2 you have to find out if the gearbox housing is now worn oversize in which case you will need a solution or hopefully the seal OD is undersize then all you need is a new seal.
1 member likes this
#850768 Jun 5th a 12:51 PM
by kommando
kommando
No means No, even leaned over so the oil level goes higher on the seal side it should not leak through the seal.
1 member likes this
#850775 Jun 5th a 02:55 PM
by kommando
kommando
So your housing is worn, you will need a solution to that.

1. Look at the seal catalogues, including metric ones, and find a seal with the same ID and thickness as original but a slightly larger OD.

2. Get the shell welded up and then machined back to standard size

3. Get a second hand gearbox shell
1 member likes this
#850786 Jun 5th a 04:31 PM
by kommando
kommando
Originally Posted by Z900
Thanks kommando, really helpfull !

1. Could it be the case that the bearing is too deep in the casing, so there is too much space for the circlip to hold down the seal?

2. How do you take out the bearing? Can it be done from the outside? If so, what do I need ?

1. The circlip locates the seal axially, ie in and out, it cannot hold the seal and stop it from spinning, this is performed by the housing giving a slight interference fit with the seal. The bearing may be located wrongly but that has no effect on the spinning seal.

2. You need to find out which of several gearboxes used on the B33 and get the service sheet for it to change the bearing (it goes by frame ie rigid, plunger or swingarm). The case will need heating and the bearing is driven back into the case, it cannot be removed from outside. But I doubt this is the issue as your gearbox would be locked solid if the bearing was too far in.

Service sheets

https://partsbooks.britishonly.com/#BSAService

BSA did not print workshop manuals until the early to mid 60's, before then they issued service sheets.
1 member likes this
#850794 Jun 5th a 05:32 PM
by kommando
kommando
It looks like this is a top hat seal rather than a normal garter seal, so maybe it does not rely on the OD, but if the bearing is too far in then the gearbox would still lock. Maybe the circlip slot is worn.

Answer could be here

https://www.a7a10.net/forum/index.php?topic=8786.0
1 member likes this
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