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1949 upright gearbox clutch drag

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The clutch frees quite easily on second kick, but when the machine is in motion it drags causing sometimes difficult gear changing. When the machine comes to rest it still wants to move forward even with the clutch lever pulled back to the handlebars, though this is not always the case.

I replaced the clutch springs with the later ones as supplied by the NOC which are  slightly longer than the originals, placed a 1/4" ball at the clutch end of the pushrod and replaced the 3 flanged screws holding the springs. I tightened these screws fully home as that's how I think they are meant to be.

I am at a loss of what to do next, any advice would be most welcomed

 

 

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There are many reasons why a clutch will drag.  You may find the problem easily ,or it may take many weeks of patient investigation. Worn components, incorrect parts or poor assembly and setting up ,any or even all together is possible.   Start with checking you have truly flat plates and that the clutch lfts and spins evenly. Use very thin oil in the case,and the bare minimum needed for the chain to kiss the oil surface.  My later(AMC) clutch dragged for years until I found a faulty spider in the center and reduced the clutch basket wobble with non std rollers.  Good luck!!.I don't think the springs should be fully tightened ( But I am not familiar with the early clutch).

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Hi Robert,

   See John Day's thread,   es2 clutch laydown box  , from last month as the clutch is the same on both gearboxes. I always tighten the spring retaining screws. If the pressure plate doesn't lift evenly you can shim the spring(s) with a suitable washer.

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... is a common cause of clutch drag on these but needs the gearbox dismantling. The culprit is usually the bronze thrust washer on the main gear.

In theory, the mushroom head on the clutch pushrod thrust pin should keep the pressure plate reasonably square even if the springs are of slightly different strengths.A previous owner of my bike actually made one of these with a deeper section which probably improves it further.

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The last time I had my clutch rubbers replaced, they were ridiculously stiff to insert and ended up with the spider not fully flush in place. If I had put it in like that, it would never have worked properly. Maybe worth looking at. The old rubbers were swollen but otherwise OK, so I trimmed them with a Stanley knife and put them back! (Current Norton clutch rubbers are not fit for purpose...)

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That's an interesting point David, if the problem persists I shall look in that direction. Thanks.

 

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