Crankshaft Fix

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
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Shorty
Posts: 19
Joined: Sat Feb 04, 2017 11:49 pm
Location: WESTERN AUSTRALIA AUSTRALIA

Crankshaft Fix

Post by Shorty »

The right hand side crankshaft thread on my G80CS is stripped. This is the left hand threaded side, under the camshafts.
Is there any easy way to fix this or is it a complete tear down?
bitza
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Joined: Tue May 27, 2003 1:00 am
Location: SHROPSHIRE UK

Re: Crankshaft Fix

Post by bitza »

Looks like a strip down bud, unless the experts know of a easy fix.
SPRIDDLER
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Re: Crankshaft Fix

Post by SPRIDDLER »

Rotten luck.
Not something I've been faced with but as I happen to be logged in at the mo I'll throw in my two penn'orth.
Strictly speaking the timing side axle needs to be replaced which means a strip down and splitting the flywheels.

However, the timing side pinion is keyed to the axle and I imagine that it doesn't have a great axial force on it when driving the straight cut valve gears. In my experience it usually needs a seriously strong puller to remove the pinion from the axle. I don't know whether it would be possible as the axle will be hardened but (MickD should look away now ;) ) maybe a new thread (even a metric thread) could be cut with the axle in situ if a l/h metric nut is available - but it would only ever be a bodge and a strip and axle replacement is the only proper fix .
Last edited by SPRIDDLER on Thu Sep 30, 2021 1:16 pm, edited 1 time in total.
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Which taken at the flood............'
Mick D
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Location: Aberdeenshire

Re: Crankshaft Fix

Post by Mick D »

Hi

As the axle is now bu****ed, you're looking for a quick fix and as Sprid has pointed out there's little force on the gearing, I'd think about welding the nut in place on the axle. When the time comes to fix things properly you should be able to grind off the nut to reclaim the gear for installation on a new axle.

Regards Mick
Shorty
Posts: 19
Joined: Sat Feb 04, 2017 11:49 pm
Location: WESTERN AUSTRALIA AUSTRALIA

Re: Crankshaft Fix

Post by Shorty »

Thanks Gents.
I was a bit worried that it would let go or the nut would come off and smash the timing housing. I will give it a tack with the mig and see how we go!
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