Oil leak from gearbox final drive

[BSA500]

It leaked so bad I filled it with the graphite grease used by Landrovers in the swivel(sp) steering joints.

[Topdad]

Good news about that BSA500 is that when you fix it the box should feel as could be , mine was transformed when i did mine, regards bobH

[DazSeaton]

Just a word here, when I did my last box up the large oil seal over the output shaft was slightly oversize meaning it would not fit into the end of the box without a bit of filing around it's perimeter.
Now with hindsight I should have sent it back and got a replacement because making it fit around the outside could mean it doesn't put even pressure on the shaft because it may not be central after filing.
I think I would have taken enough off so that the seal had some float - but memory's not my strong point

Bill,
Both the one I took off and the new one were too large to enable the circlip to slip into the recess. Checked the bearing was fully in and then ended up grinding a millimetre off all round to get it to fit. In fact I am hoping that this was the problem causing the oil leak, in the fact that the circlip was not in the recess and pressing the seal onto the outer bearing face.
Darren

[bsa-bill]

Yep , that was exactly the problem I had Darren

[Topdad]

Hi Bill and Darren, doe's anyone know if a plunger box circlip is slightly thicker than the s/arm one? if so and over time suppliers could just be making the "new" type ,just a thought ,as you 2 had the same problem and just by chance did you both get the circlips from the same dealer ? regards bobh

[bsa-bill]

Hi Bobh
Can't recall now where I got the seal from, sorry not much help.
My box is a S/A one if it is the original box for the bike and the spare box I bought is supposed to be S/A also, however all four selector forks have the plunger part number so who knows you might well have a good point there.
It also has to be said I bought some "Genuine" S/A selector forks from one of the lesser known BSA dealers, the parts arrived from somewhere else altogether with the part number ground off ??? (once bitten), it also has to be said that nobody seems to know what if any difference there is between Plunger and S/A selector forks apart from the part number

[DazSeaton]

Hi Bill and Darren, doe's anyone know if a plunger box circlip is slightly thicker than the s/arm one? if so and over time suppliers could just be making the "new" type ,just a thought ,as you 2 had the same problem and just by chance did you both get the circlips from the same dealer ? regards bobh

The spring clip fits in the recess perfectly, there is not enough gap between the outer face of the bearing and the clip to get the seal in unless you reduce the size on the seal. the seal only just fits throught the outer gearbox casing.

[chaterlea25]

Hi All,
Yes!! I have several battles fitting the seal and circlip
Theres a little ridge at the back of the seal which has to be compressed against the bearing outer ring to form an oiltight point
Along with the seals being a little oversize in diamater it makes fitting them a ""challenge""
The seal edge can also easily slip into the circlip groove
A little rub with a file around the outer edge helps
If the gearbox is out or stripped apart a piece of suitably sized tube and and a large bolt and some Big washers can be used to compress the sealing lip against the bearing, this can help a bit !!
the other method is to centeralise the seal and fit the circlip into the housing , then use a flat ended punch to tap gently all round the circumference of the circlip till it seats into the groove
HTH
John O R

[BSA500]

See my reply in the Sleeve gear bushes replacement topic for more fun and games