Stripped Thread Final Drive
Posted: Wed Sep 12, 2007 1:37 am
Hi Peter,
personally, I like Helicoils, so much so that I sometimes put them in on new threads in aluminium castings to beef them up, as Norton did on the ally head ES2s etc.
Yes, its possible to build the (bare) case up with weld and machine it but I've seen a few cases ruined this way by distortion, and although modern ally welding techniques are better, I'd avoid trying that until all other options were used up, especially on something as sensitive as your final drive case. There's also a product called lumiweld which uses zinc alloy at low temperatures but I've not used it myself.
My own inclination would be to strip it, drill it oversize and make a bush from Phosphor Bronze or similar, tapped internally to take your original plug (which I'm guessing will probably gently knock out with a drift from the inside), to screw into the case and be loctited in, although it is visible, once done its actually better than new. Its an old fashioned way of repairing it, but if we didn't think old fashioned was best we wouldn't ride these bikes, would we?
Good luck with it
Cheers
personally, I like Helicoils, so much so that I sometimes put them in on new threads in aluminium castings to beef them up, as Norton did on the ally head ES2s etc.
Yes, its possible to build the (bare) case up with weld and machine it but I've seen a few cases ruined this way by distortion, and although modern ally welding techniques are better, I'd avoid trying that until all other options were used up, especially on something as sensitive as your final drive case. There's also a product called lumiweld which uses zinc alloy at low temperatures but I've not used it myself.
My own inclination would be to strip it, drill it oversize and make a bush from Phosphor Bronze or similar, tapped internally to take your original plug (which I'm guessing will probably gently knock out with a drift from the inside), to screw into the case and be loctited in, although it is visible, once done its actually better than new. Its an old fashioned way of repairing it, but if we didn't think old fashioned was best we wouldn't ride these bikes, would we?
Good luck with it
Cheers