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Gary E
Gary E
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B31 1949 ZB plunger clutch removal
#809471 05/19/20 2:37 pm
Joined: Oct 2016
Posts: 58
Ian T Offline OP
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Hi

I wonder if someone could help.

I'm trying to remove the primary backplate to access the gear sprocket. I've got the single spring clutch basket off but I'm left with these which I cant work out how they are removed...

I assume this comes off first (screw drive pointing)
https://s1067.photobucket.com/user/Iantinley/media/INNER_zps0wm96a1m.jpeg.html?sort=3&o=1

then this (finger pointing).

https://s1067.photobucket.com/user/Iantinley/media/INNER_zps0wm96a1m.jpeg.html?sort=3&o=1

should they be pulled off or are they on a thread?


Any help greatly appreciated.

Ian


Sunbeam S7 Deluxe 1949
Suzuki GP100 1979
Suzuki GT500 1977
BSA B31 1949 ZB Plunger
BMW R1150 RT 2003
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Re: B31 1949 ZB plunger clutch removal
Ian T #809524 05/19/20 10:11 pm
Joined: Feb 2014
Posts: 661
Likes: 14
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Hi Ian,
That complete part is attached to the main shaft on a taper/key there is a nut in the centre of the clutch adaptor
Remove the centre nut, either get a suitable threaded puller to screw onto or into the threads on the outer end, or
screw on the clutch spring nut and use a suitable puller on that
They can be really tight, I have found that after tensioning the puller pouring boiling water over the centre will expand them enough to pop off
its the shock heating that works, heating with a heat gun or blowlamp allows time for the heat to transfer into the inner shaft
Its better than whacking the puller with a hammer
The parts diagram is on line at https://www.baxtercyclebooks.com/FB/BSA_1949-58_M_Models/30/index.html

John

1 member likes this: Ian T
Re: B31 1949 ZB plunger clutch removal
chaterlea25 #809569 05/20/20 9:55 am
Joined: Oct 2016
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Ian T Offline OP
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Hi John

Thanks for your reply. First thing this morning, I did what you advised- reattached the nut, put my three pronged puller on the part and off it pinged- no heat needed! So pleased. The parts diagram you sent is fab- the bike is new to me so it seems someone has put an M20/21 clutch and parts on the bike. I'm hoping there's a seal on the gear sprocket as I'm leaking clean gear box oil. Also, I'm going to replace the crankshaft seal cause its leaking dirty oil into the primary. Here's to an oil free bsa!!! (hopefully)

Best wishes

Ian


Sunbeam S7 Deluxe 1949
Suzuki GP100 1979
Suzuki GT500 1977
BSA B31 1949 ZB Plunger
BMW R1150 RT 2003
Re: B31 1949 ZB plunger clutch removal
Ian T #809678 05/20/20 9:06 pm
Joined: Feb 2014
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Hi Ian,
The M clutch was fitted I believe for some markets or a previous owner could no longer live with the six spring clutch
The Baxter cycle parts books on line are a valuable asset sitting here in the armchair and not having to go and search through books in the shed
Unfortunately it looks to me as though a gearbox strip is needed to replace the oil seal in the box ? Its been quite a few years since I had one apart and cannot remember exactly?? Oil will also leak out along worn high gear bushes !
There is no seal between the engine and primary it relies on a shim washer that acts as a labyrinth seal
Wet sumping is a much discussed topic elsewhere

John

Re: B31 1949 ZB plunger clutch removal
Ian T #809695 05/20/20 10:13 pm
Joined: Oct 2016
Posts: 58
Ian T Offline OP
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Hi John

I’m starting to realise why Bsa’s leak! I can’t understand why bsa didn’t fit a renewable seal between the crank and primary, just in case - I will have to sort out the wet sumping in that case.

And the same said of not having a seal that can be replaced from the outside of the gearbox without having to delve into it! In that case, I’ll start to remove the gearbox To get at that seal!

Thanks for all your help and advice.

Best wishes

Ian


Sunbeam S7 Deluxe 1949
Suzuki GP100 1979
Suzuki GT500 1977
BSA B31 1949 ZB Plunger
BMW R1150 RT 2003
Re: B31 1949 ZB plunger clutch removal
Ian T #809880 05/21/20 11:16 pm
Joined: Feb 2014
Posts: 661
Likes: 14
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Hi Ian
The later pre unit gearboxes have the sprocket seal fitted from the outside
Get a set of BSA service sheets for the B31, That and the parts book are essential

John


Moderated by  Allan G, Jon W. Whitley 

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