Author Topic: B31 clutch & primary drive  (Read 442 times)

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BeenyBoy

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B31 clutch & primary drive
« on: 13 February, 2018, 17:38:23 »
A little advise please-

I'm trying to rebuild the primary drive and clutch on my B31 (M m series gearbox + 6 spring clutch)

Inner chain case and sliding plate fitted -
-felt and cork washer behind the splined sleeve-
-2 row bearing and rear plate onto the sleeve

all as per service sheet and manual- but when I fit the clutch centre and tighten the mainshaft nut it tightens down but leaves the chain wheel loose and- for want a a better word "wobbly"- Further tightening of the nut results in the clutch centre becomes fixed and will not rotate

I cant see what I'm doing wrong- as the order of assembly is as per the worksheet and I cant really see how else it can fit together- what am I missing ?

any thoughts ?

 

LJ.

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Re: B31 clutch & primary drive
« Reply #1 on: 15 February, 2018, 10:32:20 »
If I remember rightly there always was an acceptable amount of wobble with the six spring clutch. Draganfly improved on a better bearing which is a solid aluminium ring with two rows of ball bearings, I found this a considerable improvement, however on my B33 I eventually replaced six spring clutch to a four spring, for better. My m21 from six to an even better believe it or not, single spring.

BeenyBoy

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Re: B31 clutch & primary drive
« Reply #2 on: 15 February, 2018, 17:40:10 »
Thanks LJ...  I'll give that a coat of looking at- I find that if the centre is tightened down there is about eighth inch forward and back free play on the chain wheel- but this largely disappears once the  springs and cover are fitted; Everything will rotate although all it feels very tight. I'll strip it down again tomorrow and have another look
cheers

LJ.

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Re: B31 clutch & primary drive
« Reply #3 on: 15 February, 2018, 20:03:40 »
Hi Beeny, The six spring clutch requires a LOT of patience in getting it right and it can be done as I have once found, and it was a good un for a long time until it eventually needed adjustments, and taking apart it then it became a pig and was never the same again, which is why I swapped for a four spring clutch... never looked back. One would have thought that six springs would have been much more even than four, I could never work out why the four is better though.  :o

ANDY HIGHAM

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Re: B31 clutch & primary drive
« Reply #4 on: 15 February, 2018, 20:48:35 »
I have a 6 spring clutch on my B31, it is light, frees off well, does not slip or drag and was not made by BSA

20160221_114636_zpslshptepm by Sigma Projects, on Flickr

BeenyBoy

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Re: B31 clutch & primary drive
« Reply #5 on: 16 February, 2018, 16:46:13 »
Thanks- Stripping and rebuilding it (again !!) and I think I've ascertained what the problem is- I think that the centre sleeve -and/or the shaft - have worn so that the when the centre nut is tightened the sleeve is hard up against the casing -or final drive sprocket- which is why the cork washer is crushed and it is difficult to rotate the clutch centre when tightened up - so....the answer is........ answers on a postcard ...to....this is going to be Expensive !!!!

ths

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Re: B31 clutch & primary drive
« Reply #6 on: 18 February, 2018, 15:58:18 »
Andy that clutch looks impressive, where did it come form please?

ANDY HIGHAM

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Re: B31 clutch & primary drive
« Reply #7 on: 18 February, 2018, 20:19:39 »
The inner drum, basket and pressure plate are Suzuki GS850 shortened by one plate. The sprocket is a standard plate sprocket fitted with a ball race onto a modified BSA centre. A modified rusty old BSA inner drum unites the Suzuki drum to BSA centre

20151116_210940_zpsvoqppleh by Sigma Projects, on Flickr

20151115_190402_zpslfisfmsi by Sigma Projects, on Flickr

20151116_211017_zpsobynshqb by Sigma Projects, on Flickr

20160215_085908 by Sigma Projects, on Flickr