BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Fraz on 05 May, 2025, 23:43

Title: B31 Plunger - Clutch Basket sheared off.
Post by: Fraz on 05 May, 2025, 23:43
Hi. Today, whilst riding, my clutch basket came off.
It appears that there's a large nut with a flange with a flat (that holds the clutch basket on the shaft) that had come undone.

I'm sure the flat must be for locking but can't see anything to lock it with.

Are there any exploded diagrams of the 6 spring clutch assembly anywhere please?
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: DAVE BRADY on 06 May, 2025, 07:34
Hi,

It looks like the shiny washer serves as a lock washer with the edge turned up against the flat on the nut.  Also, it looks like the washer is the wrong way around as the lip is not quite flat to facilitate turning it up against the nut.

Dave.
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: scifi on 06 May, 2025, 10:29
Bit confusing this...  First is the washer supposed to be first on the shaft, or second , after the clutch basket is fitted..?

Second, what are the two threads on the shaft..?  Does the nut go on the big threads or the small threads..?   There must be two sizes of nuts.
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: DAVE BRADY on 06 May, 2025, 11:18
Hi,

The large thread is for the puller and the smaller one is on the gear box shaft. 
Clutch hub then washer and then nut.
It looks like some sort of thread locker has been used but as well as the lock washer and optional thread locker, the nut must be very tight. 
70 ft/lb of torque for A65 so probably about the same for most clutch nuts unless otherwise specified.

Dave.
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: Andy Kay on 06 May, 2025, 13:17
Part Diagram here:
https://partsbooks.britishonly.com/partsbooks/20-10193C.pdf
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: Fraz on 06 May, 2025, 15:42
Quote from: Andy Kay on 06 May, 2025, 13:17 Part Diagram here:
https://partsbooks.britishonly.com/partsbooks/20-10193C.pdf

Fantastic, thank you.

It would appear that I've not got part 65-3822 (Main shaft locking washer)

You're a star
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: cdsdorset2 on 06 May, 2025, 16:58
Quote from: Fraz on 06 May, 2025, 15:42
Quote from: Andy Kay on 06 May, 2025, 13:17 Part Diagram here:
https://partsbooks.britishonly.com/partsbooks/20-10193C.pdf

Fantastic, thank you.

It would appear that I've not got part 65-3822 (Main shaft locking washer)

You're a star

You have the washer, its under the nut.
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: Fraz on 06 May, 2025, 17:49
Quote from: DAVE BRADY on 06 May, 2025, 07:34 Hi,

It looks like the shiny washer serves as a lock washer with the edge turned up against the flat on the nut.  Also, it looks like the washer is the wrong way around as the lip is not quite flat to facilitate turning it up against the nut.

Dave.

Hi.
Having now seen the parts diagram, I now understand what you're saying.

It looks like I do infect have the tab washer (that I thought was missing) but it's been fitted before (under) the clutch basket - which is wrong and probably the wrong way up because there's no way to "lock" it on to the flat of the big nut.

Looks like (from an eBay picture of the tab washer) that it should be dished outwards so it can be more easily bent up to lock.

Thanks for your advice
I'll take a closer look tomorrow
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: Fraz on 06 May, 2025, 17:50
Quote from: scifi on 06 May, 2025, 10:29 Bit confusing this...  First is the washer supposed to be first on the shaft, or second , after the clutch basket is fitted..?

Second, what are the two threads on the shaft..?  Does the nut go on the big threads or the small threads..?   There must be two sizes of nuts.

Having seen the parts diagram, it looks like my tab washer was incorrectly fitted under my basket
Title: Re: B31 Plunger - Clutch Basket sheared off.
Post by: Fraz on 06 May, 2025, 18:50
Quote from: cdsdorset2 on 06 May, 2025, 16:58
Quote from: Fraz on 06 May, 2025, 15:42
Quote from: Andy Kay on 06 May, 2025, 13:17 Part Diagram here:
https://partsbooks.britishonly.com/partsbooks/20-10193C.pdf

Fantastic, thank you.

It would appear that I've not got part 65-3822 (Main shaft locking washer)

You're a star

You have the washer, its under the nut.

Yeah, it was fitted BEFORE the basket (incorrectly) by previous owner.