Author Topic: B31 gearbox output shaft splines  (Read 127 times)

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oldgeeza

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B31 gearbox output shaft splines
« on: 20 April, 2022, 10:43:39 »
 TPO had ridden it with the g/box pivot hanging out, thus odd wear to chain and sprockets. G/box sprocket issue. The one fitted has splines and flutes of the same dimmensions, and the replacement has narrow flutes, about 1/2 the width of the splines.  So the question is.....any ideas as to what machine the gearbox orriginaly would have been fitted to. It is marked STD.
Oldgeeza

idie

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Re: B31 gearbox output shaft splines
« Reply #1 on: 20 April, 2022, 13:16:57 »
I think only gearboxes for the swinging arm BSAs were marked as STD. GoldStars were RRT2 for instance.

JulianS

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Re: B31 gearbox output shaft splines
« Reply #2 on: 20 April, 2022, 14:08:50 »
The flutes/splines on the sleeve gear of the swining arm heavyweight gearboxes are all the same.

They were available with different number of teeth and the B31/B33 had a narrower sprocket to take a 5/8 x 1/4 rear chain til 1957. The A7/A10 and 1958 on B31/B33 took a 5/8 x 3/8 chain with wider sprocket to suit.

Photo shows the sleeve gear flutes/splines - left from a box STD T with layshaft needle rollers and right a box STD with layshaft bushes - the same flutes/splines on both.