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AMC gearbox nut behind clutch lifting mech

Been years since I worked on one- RH thread yes?

thanks

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The only left-hand thread on the AMC gearbox is the big nut that holds the sprocket onto the Sleeve gear shaft. It sits outside the gearbox behind the clutch and primary case.

All the threads inside the gearbox are right handers.

In reply to by philip_hannam1

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Thanks so many years since i did one, still got my thin box spanner for inner case nuts that i spark eroded from solid bar 40 years ago! I also made one for the sprocket nut that had a hole for the clutch thread to come through and the clutch nut lightly screwed on, no more slipping off the sprocket nut, just got to find it!!!

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I have a clutch on my dominator 99 that is always reluctant to disengage, I’ve checked everything and replaced parts that looked suspect to no avail. I think I may have found the problem, I as a last resort placed a dial indicator on the drive shaft and have established that it is clearly bent and when checked at the diameter of the clutch sprocket is quite considerable. Has anyone else experienced this?

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People racing Nortons post-war quickly found out that those with AMC gearboxes struggled when more than 60BHP started arriving at the clutch. This amount of power was easily exceeded with a well-tuned 650 or 750 engine and the racing brigade noticed gearbox shafts bending enough to shed teeth.

This problem was highlighted by people who purchased Commandos to race and actually swopped the Triplex chain drive set-up for a weight-saving simplex job. Finding out the hard way why the Commando was gifted a triplex chain in the first place. 

The Factory racing team at one point resorted to fitting an outrigger bearing in the primary case to help keep the mainshaft straight. 

The more obvious reasons that could cause a permanent kink in a gearbox main shaft. Bad engine seizure or rear wheel lock-up top of the list.

In reply to by philip_hannam1

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The lock ring/tab washer is very important too, as I found out to my cost when steaming across Dartmoor in the dark in about 1965!  For some obscure reason I hadn't put it back on when I reassembled after previous spannering.  The nut worked loose and caused a clattering and metallic noise on the chainguard, causing me to stop on a hill trough a woodland stretch of the main road.  I used the battery box lid to drain the oil into and took off the outer casing to find out what was going on.  That didn't help much as I then realised it was the sprocket - behind the inner case.  No way was I going to try and remove the clutch in the dark so I think I managed to tighten the nut up a bit and saw that it couldn't actually fall off!  I continued my journey home to Southampton without any more problems.

 


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