DynamoDrive chain

itma · Post by **itma** » Sun Mar 25, 2012 11:38 pm

sledgehammers and nuts again

take trouble to line it all up right, and the chains will not touch nor spring links dislodge.

laxy · Post by **laxy** » Mon Mar 26, 2012 12:13 am

hi fump,you say you cant get an endless chain for the dynamo.I had no problem getting one from jsl last year. Youve got to take the chaincase off any way so how long does it take to undo a nut, pull off the shock absorber spring and cam and pull the engine sprocket off,1/2 hour? when its all back together make sure both sprockets are running in line before adjusting chain and tightening the strap.Dont forget there is a metal strip with upturned edges that screws to the dynamo body between the engine plates to stop the dynamo moving sideways if by any chance the retaining strap comes loose.A forum search will recall this very subject from last year.

bigwol · Post by **bigwol** » Mon Mar 26, 2012 10:16 am

What fump said laxy was he couldnt get a dynamo chain that wasn't endless.
You are quite right, the correct parts should be used and had the dealer i bought it from fitted the dynamo he had re-wound with a woodruf key, correct nut locking washer and circlip I doubt the sprocket would have fallen off! This guy incidentally is not a back street dealer but has a show room and workshop set up, offering servicing repairs and MOT's.
Needless to say he will not be doing any work on my bikes!
I didnt remove the engine sprocket, got the dyno chain on as you suggested, on the sprocket then sprocket to dyno, the primary went on by moving the gear box fully forward and feeding onto the chain wheel.
Ken, i did indeed take plenty of time to make sure all was lined up and adjusted correctly. What oil should i use in there?

itma · Post by **itma** » Mon Mar 26, 2012 11:07 am

naughty bigwol

clive · Post by **clive** » Mon Mar 26, 2012 11:09 am

A trick for refitting the primary chain without moving the gearbox. Assuming it was correctly tensioned before you took it off and you have a spare spring link then turn the engine/clutch basket until the two ends of the chain are fully engaged with the clutch basket gear towards the rear of the bike. Push the spare spring link 3/4s of the way on to both ends. Then rotate the engine forward so that the spring link is placed halfway along the dynamo chain run. At this point there is enough clearance to fit the other spring link from behind the chain, pushing out the spare link as it goes in. Bit fiddly but much quicker than moving the gearbox forwards and backwards.

fump · Post by **fump** » Mon Mar 26, 2012 9:01 pm

Thanks for all your comments. A Woodruff key is not used with the very similar Magneto drive arrangement. So why is it needed here? I wondered after my disaster, if it had not been there perhaps the chain would have remained unbroken because the sproket would have then rotated on the dynamo shaft......... not ideal but not disasterous either.
How about using a drive belt instead?

wilko · Post by **wilko** » Mon Mar 26, 2012 11:56 pm

It's only there to stop the shaft turning when tightening the nut with a spanner on the flat of the back of the sprocket. I've used a maggy sprocket on mine for the last 8 years.

clive · Post by **clive** » Tue Mar 27, 2012 12:37 am

but without the woodruff key its not possible to use the locking arrnagement for the nut (tab washer and circlip) can you lock it up sufficiently without? I too used a mag sprocket on an Alton alternator for years, only locktite to stop the bolt unwinding. somehow the woodruff key andn lock washer give more reassurance. I have just fitted, removed and refitted two dynamos (one motored but did not generate) in a couple of hours, including fitting a new endless dynamo chain. do not see why its a problem and you are thinking of changing to belt drive. This sort of maintenance is going to be a regular feature if you drive a 50+ year old bike any distance.

bigwol · Post by **bigwol** » Tue Mar 27, 2012 10:19 am

quote:
It's only there to stop the shaft turning when tightening the nut with a spanner on the flat of the back of the sprocket. I've used a maggy sprocket on mine for the last 8 years.

My understanding is that woodruff keys are used to prevent sprockets turning on the shaft under load and loosening the retaining nut. If you've ever had an engine with a mag flywheel this becomes clear as any damage to the keyway results in a poor fit and usually the flywheel slipping and wear on both the shaft and seating to the flywheel. The load on a dynamo at full charge is probably much higher that with a mag, perhaps thats the reason one has a key and one not?
Whatever the reason, if there is an undamaged keyway on the shaft I will use one as well as the lock washer / nut / circlip arrangement which seems to work.

itma · Post by **itma** » Tue Mar 27, 2012 4:26 pm

if you had a key way on the magneto how will you time it?