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#850756 06/05/21 10:22 am
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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

Last edited by Z900; 06/05/21 10:25 am.
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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.

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Thanks kommando !

So for 1. you mean there is no problem ? Is this only the case because the gearbox is leaning to its output shaft?
In other words: when the gearbox is horizontal there should be no oil leakage ?

I made a movie for 2.of the rotating seal, its uploading for your info. (I did put on a new seal):



Cheers, Gerrit

Last edited by Z900; 06/05/21 12:45 pm.
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No means No, even leaned over so the oil level goes higher on the seal side it should not leak through the seal.

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These seals should be a pain to fit the clearance is so tight. I usually
Find warning the case up with a heat gun aids fitting, then get the circlip in quick.


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Originally Posted by Allan G
These seals should be a pain to fit the clearance is so tight. I usually
Find warning the case up with a heat gun aids fitting, then get the circlip in quick.

Wow really? Its easy here to fit.....

Here the turning of the new installed seal:


Last edited by Z900; 06/05/21 2:31 pm.
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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

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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 ?

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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.

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What a great help !!! Appriciate it so much,,,,,,,,,

My B33 is a swingarm 1957 BUT with GB prefix motor (it should have an altenator but it doesn't), I dont know why this is......

1. Ow wow, I misunderstood then, I take a look again to see the casing of the gearbox were the sealing fits if there is worn.....

Thanks !!

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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

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[quote=kommando] Maybe the circlip slot is worn.

Thank you so much !

Yeah that was my idea too, I coundn't imagine that the seal has such a narrow fit........

[Green] = circlip space is approx. 0.11 inch

The circlip thickness is 0.055 inch

[Linked Image from i.gyazo.com]

[Linked Image from i.gyazo.com]

[Linked Image from i.gyazo.com]

Last edited by Z900; 06/05/21 7:20 pm.
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Here the difference between circlip thickness and the circlip space:

[Linked Image from i.gyazo.com]

Last edited by Z900; 06/05/21 7:50 pm.
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FYI:


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And here is the solution: a 2 times thicker circlip. Now the seal isn't turning anymore and no leakage.

I dont know yet if the previous owner has puted in a wrong circlip (seems pretty original though), or the circlip has worn out the groove (no signs of dirt from the alu carter alltough).

[Linked Image from i.gyazo.com]


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