Author Topic: Swing arm frame gearbox removal  (Read 618 times)

Offline a101960

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Swing arm frame gearbox removal
« on: 22.10. 2013 12:30 »
Lately I have experienced some shift problems. (1st to 2nd sometimes shifts ok sometimes not.The action feels stiff) Is it possible to remove the gearbox without first removing the engine? Or can the box be worked on in situ? Anyone got any ideas about what the problem might be? The box seems to function well when I first ride off. The problem seems to start after I have been riding for 20 minutes or so. Could this be a clutch problem maybe? I know nothing about gearboxes! I would be very grateful for any advice. Thanks in advance.


Online bsa-bill

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Re: Swing arm frame gearbox removal
« Reply #1 on: 22.10. 2013 16:31 »
Hi John - Think your suggestion re the clutch could be close to the problem , possibly dragging a bit, I think I'd be inclined to examine the clutch, the plain plates in particular for flatness,
replace any that rock on a known flat surface ( thick glass plate from some discarded domestic appliance ), and of course the pressure plate lifting square
If funds allow the alloy pressure plates as sold by SRM and Lyford Classic are a good investment .
Can't think of anything in these boxes that would be to much bothered by it heating up, maybe the indent plunger spring but if you haven't altered it it should be OK.
I have had the gear change return spring break one leg so the lever still worked kind of but I lost a gear, worth a look you'd only need to remove the outer cover not the gearbox.
Keep us informed
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online morris

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Re: Swing arm frame gearbox removal
« Reply #2 on: 22.10. 2013 19:36 »
Hi John,

The box can easily be dismantled in situ. Just a bit fiddly to get to the grub screw that secures the shaft for the selector forks
It only has got to come out if you need to replace the drive side bearing (case needs to be heated up to get the bearing in)
It can be taken out without removing the engine. You just need to remove the footrest and engine plates timing side (the one that runs from the battery tray down to the engine, and the other one running underneath the box, though not sure anymore if I removed the latter last time I took the box out)
Fairly heavy box though, so best is to remove the innards before taking it out or in, or get a mate to give you a hand holding the box up while you fiddle it in place
'58 BSA A 10 SA
'52 BSA A 10 Plunger
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