Sunday, August 28, 2022

Replacing the Gear Change Spring on Swinging Arm BSA A10

Working on the A10...

Being pressed back into action for the first time in years, you sort of expect a few issues. The only thing that went wrong was the gear change return spring snapping, but did it leave me stranded? Not at all, shoot back home, take off the cover and order a new one. It was there the next day! 

So, without further ado... The outer cover comes off easily with four nuts to remove and three screws. The kickstart and gear change can stay attached at this stage and makes it easier to remove the cover. Also, the outer cover can be removed without affecting the gear indexing so makes this a very easy job.

With cover removed, you can see the offending item sticking out behind the gear change mechanism. The split pin, visible here, can stay in place, just remove the tiny circlip from the outer side of the cover and the whole unit will slide out from this side, revealing the spring.



Nearly seventy-years-old, do they make nothing to last nowadays?? I'm actually pretty happy with that. 😂

The dowels were knackered, i remember this from years ago now so what better time to replace them? Only they were that thin that nothing would grip without crushing them. Tried warming with a blow lamp, and using a Vise-grips with a stud inside to prevent the dowel crushing. They weren't budging.

After running a drill down slightly smaller than the O.D. of the dowel, I filed a taper on a bolt and ran that in there. Came out a treat!


Two new dowels, ordered with the spring, from C & D Autos, these guys are the best! Ten quid for the lot, including postage, and arrived the next day. I used to order from them in the nineties, and they're still delivering superb service. Thank you guys! 

If you need BSA parts, give them a bell on 01564 795000, you won't be disappointed.


With dowels in, cases cleaned, it was time to refit the gearchange mechanism with new spring. 


Certainly built to last!


And we're back in play. The case cleaned up like new!

I personally use instant gasket on this face without a gasket. This was because the reproduction gaskets seemed to be a bit flimsy back in the day. I could make a new one out of decent gasket paper, but this is quicker and I've never had an issue. Just use a very fine bead, no need to plaster it on thick.

And then a reversal of how it came to pieces. Again, easier with kickstart and gear lever attached when refitting. It allows you to move the kickstart into the correct position when pushing the cover home.

With screws and nuts tightened, it was refilled with oil and the speedo cable fitted. Footrest back on and she was ready to go again.




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