Norton Bike Gear Box Casing Repair. 

Hi Paul Yeah, the hot plate will heat soup and boil a kettle as well :) I'll search out Robin's spindle rebuild video, sounds interesting., Cheers!

Thanks Matty. it only needed an increase in temperature of about 80 degC to expand the bore 66mm bore about 0.1mm. Cheers!

Thanks for that information, very much appreciated, amazing stuff Loctite especially when done correctly. cheers!

Thanks for your interest and comment. Yes, I was concerned about weakening the casting which didn't seem to have a lot of strength between the bearings. It was what my friend wanted and apparently a common repair though maybe not a successful repair regarding longevity.

Thanks for that insight into Noton Bearing Failures, I was quite amazed when my friend told me that the out race of the bearing had cracked in two halves, hard to imagine how that's possible. Anyway, good to know I made the repair in the same way as others before me. Cheers!

@@GoCreatehms You may want to tell your friend to watch out for something which is rather strange but true. Frequently when this bearing starts to fail, when starting out from a standstill, your kick start arm will go back and when you pull the clutch to shift the spring will whip ahead and smack you in the back of the calf muscle in your leg. No one knew why this would happen because the kickstart assembly had nothing to do with the bearing, but this was a sign. It will do this for a day or two and then stop leaving you to think whatever was ailing it has "self repaired" itself. Trust me, it hasn't. What has actually happened is the bearing is now in full failure mode and it's only a matter of time before it seizes altogether. Don't ask how I know this........

Thanks for that info, This bearing must have quite a load on it. I'll certainly pass on the message. Cheers!

Hi Robert Time will tell whether it's worked out OK, it will be w while before it's re-assembled. The new bearing was a loose fit in the bearing housing presumably because of the damage done by the broken bearing, so I couldn't really use the old bearing location as a ref. It can only be assumed that the smaller bore was machined concentric with the bearing location, but that was slightly out of round. So it's fingers crossed. Cheers!

Perhaps original bearing broke because not in centre location meaning your fix might be the solution.

the gearbox halves were not line bored. AMC and Norton made the gear box shell on a Herbert capstan using a special two position chuck/fixture with the two positions of the sleeve gear and layshaft concentric with the sliding chuck

I met a guy recently that told me he's done many of these types of repairs on Norton gear boxes, he used his mill with a boring head rather than a lathe. Thanks for taking the time to view and comment, much appreciated.

@@GoCreatehms your welcome but mine would need both done, its a shame because the case is good otherwise

Hi Ken, yeah a boring head in the mill would have been a good option if I'd had a suitable boring head, though I'm more confident doing jobs like this on the lathe.so a good boring head probably wouldn't have changed my method. Anyway, hope to see you at a steam rally in the not too distant future, wishful thinking maybe, but we live in hope. Cheers!

Sorry, I don't know. I did this job for a freind of a freind, I don't know anything much about the bike/engine. Anyway, thanks for your interest in the video.