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Solid LH worm drive on crank

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Please help me from my nightmare of an imported project now found to have a shattered flywheel and bent rod amongst other problems.  I just can not get the worm drive nut off the T/S crankshaft which is stopping me splitting the cases (or even removing the Intermed pinion and cam chain)

I know its a LH thread and I am undoing it clockwise !

I have tried oils / shocking / lots of butane heat and in desperation even a chisel and lump hammer !

It is solid and I don't want to risk damage to the cases , its the only valuable thing left of it !

Any suggestions please before I go insane

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When all else fails I have partially  cut through one side of a nut and used a cold chisel to split it. Or a Dremel.  Where are you based?.

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I longtime thought the Dremel a toy,then my spendthrift son bought one, It now lives in my shed.

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Good time to get it out, I had the wife buy me a powered one which came in handy when I had one of the bolts holding the Z plates on strip on the reverse side so I could not get it off. I carefully cut the head off it with the dremel. You can buy a huge amount of accessories for them now.

Just make sure you have the right disc for the job if you do go down the dremel route, and safety kit.

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hello buy now the damage has been done to the threads internally  and a blow touch will not get it hot enough you need a gas cutting torch with a warming nosel on and this will heat the worm drive gear up so you can see it glow hot  and then with vice grips you can then try turning it the right way  to the left hand then it just may come way intact, brute force and ignorance never gets you any were  time to use some grey mater  instead   yours  anna j    

Hi Rob, I'm in Northampton and was pondering about the possibility of grinding through to weaken it.

I have a replacement crank for this one anyway so I would be happy to just get the cases apart safely.

Thanks Anna

I can only go to Mappgas in my workshop  but I take your point with the extra heat required, I am just anxious about the vicinity of the intermediate gear sprocket and chain.

If I do use a dremel on the worm drive teeth I would then have the clearance to rotate the crank so I can get the Intermediate and cam sprockets off with the chain and this may give me more access to the problem drive itself

I appreciate all the advice guys,  I've had continuous Triumphs since 1976 ( including same one) and know them inside out but only recently picked up a 71 Combat project  as I have fond memories of my 73 Interstate 750 sold back in 79/80 . (so long ago !)

Hi John

I have a donated dremel but am wondering the best tool head to use for this application

a thin cut across the teeth or a grind through ?   Carbide tip milling ?

I 've got safety gear and patience but want to use the right blade for such hardened metal

Maybe I can give it a crack tomorrow if I get an early reply ?

many Thanks Bob

Hi Ian

I have a nut splitter but will nit be able to get a square purchase around the drive as the intermediate gear is still unable to come off until some of the teeth are removed

also this is a particularly hard steel compared to the nuts i have used this on before

Bob

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I only have the cutting discs that came with the dremel, and not sure which ones you need maybe you can phone around.

Let me know the type of disc and if mine suit let me know I am on the boarder of Northampton pop over during the week if no success.

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Another trick is to drill a line of small holes across half the face of the nut ,slightly overlapping them ,and drive a cold chisel into them.This will release the grip on the shaft. ,The drill tip may mark the face of the worm but won't do any significant damage to it.

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I'm pleased to say that it's ages since I've stripped a Commando bottom end..I seem to have been playing around with side-valves more of late, but is the oil sealing disc, half-time pinion and worm not capable of passing through the crankcase aperture ?

If you remove the drive side half, clamp the crank in a vice and then heat the timing side case, it should be possible to lift it off , leaving the main bearing on the crank. The heat is only needed to ensure that the main bearing exits the housing without damage.

Hi guys thanks for your help

Got it off today by grinding a large flat on it to take a bit more heat from the Mapp Gas

No other damage to peripherals 

 

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