BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: RESTORER on 10 September, 2017, 21:46:19

Title: A10 STD Gearbox
Post by: RESTORER on 10 September, 2017, 21:46:19
I have my A10 S/A G Flash well into restoration but not yet running and stood on a bike lift. I have had oil in the gearbox for 2-3 months and I have just noticed a blob of oil forming on the end of the plunger housing, where the two flats are.  There is not enough oil to have dripped yet but this must happen eventually.  The plunger is adjusted so that two threads are showing when the nut is tightened.  Reading what I can find, which isn't much, and studying sketches and exploded views etc, a seal is not specified for this area so I assume that the locknut tight on the casing face together with the plunger to casing threads tightening together, must normally be capable of doing the job, meaning that I have not tightened mine sufficiently.  Before I go any further can anyone answer a couple of questions: Is this a common problem with a known fix? and if the cam plate is kept in neutral can the plunger housing be disturbed for inspection/resetting and re-tightening without resulting in a total strip down?  Any views on this would be very helpful.  Thanks for reading.  restorer
Title: Re: A10 STD Gearbox
Post by: JulianS on 11 September, 2017, 09:43:04
Not normally a source of a serious leak. My A10 has a smear of oil, see photo, which is how it looked this morning after use since May this year, when last gunked off.

I presume the oil is not forming on the plunger having leaked from another joint.

No problem with removing the plunger housing, the correct gear indexing is set by the quadrant being in correct relationship with the cam plate when inner cover is replaced and this can only change if the inner cover is removed.

I would remove the plunger and examine the area around the thread. I apply a small amount of gasket sealer to the threads, or you could try PTFE tape which has many uses on our old bikes.
Title: Re: A10 STD Gearbox
Post by: RESTORER on 13 September, 2017, 21:08:44
Thanks yet again Julian, I have removed, cleaned and refitted the assembly, using the PTFE tape method as I already had some. Only time will tell but after a couple of days the assembly is still bone dry and with the bike not finished yet, I can monitor for a while.