The BSA Workshop > Pre War

1929 Sloper "challenge"

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Hi folks, Just recently joined BSAOC and just recently purchased a 1929 S29 Sloper 500cc OHV. She has been running fine but when I took off primary chain and cush drive for a bit of cleaning/maintenance, I noticed there is some "rotational" play on the crankshaft drive stub ie: you can rotate the crankshaft stub that sticks out into the primary drive chaincase easily with your fingers WITHOUT rotating the engine!! The rotational play is about  1/16" on as measured at the max diameter of the crankshaft stub. I am assuming this is not normal and am planning on engine removal and splitting crankcases to see what on earth is going on. I have heard that the drive-side crankshaft stub is rivetted to the left hand flywheel, which to me as an engineer, sounds an "intriguing" way of fixing the two together! And i have heard these rivets can come loose and hence some rotational play. i guess the  only other options is that the crankshaft stub has snapped, but in a way that allows it to still transmit torque (at the moment!). This does not seem likely as there is absolutely no end float. Does anyone have any experience/comments/suggestions? (BTW -I have tried to contact Jules Dassen from the Technical Area who specialises in pre1930 models but not sure if he's on holiday or my emails are ending up in his email Junk folder?). Any help/advice much appreciated......

Article below may give some Sloper information.

Coud you post a photo of the shaft end?

Hi JulianS,
Picture showing shaft end and very short video (.mov) showing "rotational play".
Hope this helps......

Thats a problem.

The shaft is, when assembled, a very tight press fit in the flywheel and is held in position by the rivets. A common means of assembly with British single.

The only way is complete dismantling when you will no doubt find the drive shaft and flywheel damaged.

First photo is from 1930 catalogue showing what the flywheel assembly looks like and the next 2 show crankshaft parts and is from the 1929 parts book.

Good luck.

Ok. Thought it was very likely a problem! Appreciate your advice though - at least i know I've got to get crankshaft out.  Do you (or does anyone else) have any recommendations for Sloper crankshaft specialists once I get it out?


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