The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: edboy on 06.07. 2014 15:35

Title: duplex sprocket clutch
Post by: edboy on 06.07. 2014 15:35

hello, i am building up a  swing arm gold flash from a lot of old bits and pieces. unfortunately the original clutch drum and plates are scrap. however there is an early plunger engine duplex, 4 lobe clutch assembly in good condition. is it possible to fit this unit to a swing arm gearbox mainshaft? will it be too wide for the cases? could i buy a chain to fit?
i want to be on the road asap so cant afford to waste time and money on a non starter.
any information appreciated. a mate had a duplex chain on his a10 in the 80s but i think that was triumph.

Title: Re: duplex sprocket clutch
Post by: muskrat on 06.07. 2014 20:43

Short answer is no. The plunger main shaft is a spline the S/A is a taper & key.
I'd go for a 4 spring conversion.
Cheers

Title: Re: duplex sprocket clutch
Post by: BSA_54A10 on 07.07. 2014 09:35

Fairly sure that you can swap the main shafts if you really want to use the other clutch but it is a lot of work

Title: Re: duplex sprocket clutch
Post by: edboy on 07.07. 2014 18:51

thanks for replys and i will have to check mainshaft fits when i next have time i m sure the gearbox mainshaft is tapered. but would a triumph duplex clutch sprocket fit. i am sure i have an old one somewhere but would the triumph duplex chain fit the bsa sprocket? i appreciate the 4 spring clutch would be best but was trying to use up what i have already.

Title: Re: duplex sprocket clutch
Post by: trevinoz on 07.07. 2014 22:14

Ed,
         You can even fit a triplex clutch in there if you want, but first you need the sleeve to fit the gearbox mainshaft.
The Triumph duplex chain is the same type as was used on the BSA duplex primary drive.

Trev.

Title: Re: duplex sprocket clutch
Post by: BSA_54A10 on 08.07. 2014 11:57

Quote from: trevinoz on 07.07. 2014 22:14

Ed,
         You can even fit a triplex clutch in there if you want, but first you need the sleeve to fit the gearbox mainshaft.
The Triumph duplex chain is the same type as was used on the BSA duplex primary drive.

Trev.

So where does one get a tripplex cush drive sprocket ?

Title: Re: duplex sprocket clutch
Post by: duTch on 08.07. 2014 21:59

 I think he means use the duplex drive sprocket and disregard the third row on the chainwheel

Title: Re: duplex sprocket clutch
Post by: trevinoz on 08.07. 2014 22:24

One does not need a triplex cush drive sprocket as the cush is in the clutch hub.
One could also try to find a triplex cush sprocket which was used on the Super Flash and, I suspect, was an option for America.
I had one which I gave to a friend as he had the matching chain wheel.
The same bloke had the triplex set up from an A65 on his A10 for a while but has now gone back to the standard simplex set up.

Trev.