BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Barthol_18 on 10 Dec, 2025, 17:35

Title: BSA B31 Clutch Question
Post by: Barthol_18 on 10 Dec, 2025, 17:35
Hi Forum

When I checked my clutch I can move the clutch gear wheel 4 mm in / out -axial direction
Clutch assembled without clutch plates,

I understand that the springs will push the clutch gear wheel towards the gear box , and I guess it will sit like shown in image 1. My concern is that it looks like the outer ball almost clears the outer bering ring,- is this correct? The inner bearing ring is app 14 mm while tho outer is just below 10 mm( tis equals the axial play)
I do not see anyway to reduce the play. and the primary drive lines up perfect with the engine gear wheel when the clutch is complete ly mountde.

Should I be worried , Or can I just assemble the bike.

BSA B31 -Rigid from 53.
Clutch is with 6 springs

BR
Kim

Title: Re: BSA B31 Clutch Question
Post by: idie on 10 Dec, 2025, 18:05
That is  normal on the BSA 6 spring clutch. They always look as if they are falling apart. Once running they centre up with no problem.
Title: Re: BSA B31 Clutch Question
Post by: Barthol_18 on 11 Dec, 2025, 05:08
Ok Thanks a lot, as just concerned about the position oft the outer ball ring:-)

By the way, I can see that the Bearings can be bought as separate parts i.e. only the galls and the thin ring they are mounted in.

Do you know how to get the balls/ thin ring mounted on the inner Race with the grooves, ?
I guess that it cannot just be pressed on?


BR
KIM
Title: Re: BSA B31 Clutch Question
Post by: limeyrob on 11 Dec, 2025, 11:26
Th just pop on with hand pressure.  The ones you have look quite good, they are often a bit bent.
Title: Re: BSA B31 Clutch Question
Post by: Barthol_18 on 11 Dec, 2025, 20:09
hi ,  Some of the steel baals actually dropped put when I removed the clutch Bowl. I did put them back in , ans as soon as the Clutch bowl is installed they seem to stay in place even , they seem to be very visible and close to the edge as pr photo one

I ordered two new ball races, just in case.( they are quite cheap to buy)

BR
Kim
Title: Re: BSA B31 Clutch Question
Post by: idie on 11 Dec, 2025, 20:16
Almost half of one race will show at the back of the drum.
Title: Re: BSA B31 Clutch Question
Post by: V500 on 11 Dec, 2025, 21:28
If you're buying from Drags, then beware.
The cage and balls are sold separately from the outer race, which make it an expensive repair.
The outer was an extremely tight fit in the chainwheel (far tighter than the old one previously fitted) needing heat, chilling and a large press.
The cage also wouldn't fit on the adaptor. This needed chucking up in the lathe and a few thou removing.
Next time I would just fit new balls if at all possible.
Title: Re: BSA B31 Clutch Question
Post by: limeyrob on 11 Dec, 2025, 23:35
Hold the balls in place with grease when you assemble.
Title: Re: BSA B31 Clutch Question
Post by: neil1964 on 13 Dec, 2025, 08:22
Quote from: V500 on 11 Dec, 2025, 21:28 If you're buying from Drags, then beware.
The cage and balls are sold separately from the outer race, which make it an expensive repair.
The outer was an extremely tight fit in the chainwheel (far tighter than the old one previously fitted) needing heat, chilling and a large press.
The cage also wouldn't fit on the adaptor. This needed chucking up in the lathe and a few thou removing.
Next time I would just fit new balls if at all possible.
Same experience here with Dragnfly hub bearing replacement. Although ready to fit I have kept on shelf as spare and opted to go belt on the current build.