Shimming Gear shafts. 250nc 5speed.

bobnorton · Post by **bobnorton** » Tue May 04, 2010 10:01 am

My output shaft and selector drum have too much end play,no shims missing, which ends best to shim?

Eldert · Post by **Eldert** » Tue May 04, 2010 11:33 pm

Bob
when you put the front sprocket on the outputshaft and tighten there is
no play in the shaft anymore . only first gear has a little play

same with inputshaft when putting on the clutch

always put on frt sprocket and the clutch ( or a piece of tubing ) when
shimming the gearbox so you can pull the shaft all the way in the bearings

Eldert

bobnorton · Post by **bobnorton** » Wed May 05, 2010 8:30 am

Thanks Eldert, thats really usefull, so no point in shimming the two shafts! The drum I can shim at the selector box side ?.The new case gasket is a fair bit thicker than the oid so the crank shim will also need changing, where do you get your shims?, just found odd main bearings,one c3 and the other std (tight and noisy) Any idea what the max clearance is between crank and oil bush?I have about 4 thou, I think the crank should be 12mm but mine is not.

Chris Bushell · Post by **Chris Bushell** » Thu May 06, 2010 5:30 am

Bob,

I have a selection of shims for these engines, give me a call.

Saw your crank up at Paul Watsons on Tuesday!

Chris

bobnorton · Post by **bobnorton** » Thu May 06, 2010 7:58 am

Thanks Eldert, High Chris,The crank was in a state, Paul has done well with it, what mischeaf are you up to ?not another Duck! Have just learnt that its best to leave slack for oil access to gears and a sloppy drum works better than a tight one,so much for the manual then!!Amazing that the little red rocket went so well with so much amiss.I will be convalessing after heart work tomorrow hope they do a job like paul,Putting the motor back together will be good therapy next week, will be in touch to swap a few shims.

Chris Bushell · Post by **Chris Bushell** » Sun May 09, 2010 11:39 pm

Bob,

Just rushing round getting four bikes ready for the Moto Giro d'Italia at the end of thois month.

Get well soon

Chris

bobnorton · Post by **bobnorton** » Fri May 14, 2010 10:34 am

I'm back in the fray, replacing most of the bearings,re-shimming all the bevels, upgrading where possible,this will be a quick and quieter motor, looking at crank shims at present , not the easiest thing but satisfying when right.(I hope!!)