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How many shims are too much for the CB ?

How many shims are too much for the CB ?

Old 10-15-2009, 07:18 AM
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Default How many shims are too much for the CB ?

I was putting together a clutch out of spare parts on an old motor I had and when I put the CB on over the clutch, the motor shaft was sticking out a lot. So I shimmed it and now you can see just the edge of the clutch when you look directly down on it. I canít find my calipers so I canít give you an exact measurement but if I were to guess I would say to could see 2-3mm of the clutch shoe. Is this a bad idea to run like that? Other than this, everything else lines up good.
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Old 10-15-2009, 07:49 AM
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shim it from behind the flywheel first
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Old 10-15-2009, 07:51 AM
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You shim the clutch bell so it lines up with the gears and completely covers the clutch shoes.

You can put shims outside the bell on the shaft to get rid of excess play.
I've never had to use shims under the collet on Novarossi and RB engines.

Sounds like you shimmed it too far forward. Remove some shims and put them on the outside, on the shaft that was sticking out. You need a steel washer on your clutch bolt as well.

Leave 1mm endplay.
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Old 10-15-2009, 07:59 AM
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1mm of end play is Way too much if you ask me....... .3-.5mm is where you want it.
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Old 10-15-2009, 08:00 AM
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Thanks for the info. Ill try shiming it from the front .
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Old 10-15-2009, 08:27 AM
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Also, as you mentioned you are using spare parts to put this clutch together. Make sure you are using the right flywheel nut. I've used some form another manufacture and found some are different lengths. What happens is.. when you put the inner bearing and CB on the gap between the bottom of the CB and the flywheel are too large. So you either need a shorter flywheel nut or you maybe able to cut the nut down and then shim it back up if needed. I would only suggest cutting the nut if you have the means to make a straight cut.

One thing to consider, if you shim the brass / cone of flywheel then you will move the center line of the CB further out. The problem with this is your motor mounts may not allow enough adjustment to obtain the proper mesh to the spur gear / center diff gear.

You can shim the CB in either direction about 1mm and then tighten it up.

You might want to check into something like this:


Last edited by offr0aden; 10-15-2009 at 08:46 AM.
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