belt drives to dynamos

itma · Post by **itma** » Thu Mar 24, 2005 9:09 pm

has any body ever tried belt driving dynamos on singles?
if so was it succesful?
i`ve just had a fidget with mine to check on the noise on the chaincase, which was a chain that has become very slack in one spot, and very tight in another, making adjustment a bit hit and miss.
i`ved noticed this always happens to dynamo chains, on this bike at least, and wonder if belts are the answer, or is it just crap chain?

Biscuit · Post by **Biscuit** » Thu Mar 24, 2005 10:02 pm

Two thoughts Ken, how do you arrange a belt drive in a chaincase containing oil, (or do we have to go through the dry chain saga again) The diameter pulley required to obtain the friction required to drive 45 or 60 Watts could not be accommodated in the standard chaincase. (Have a look at the belt drive on a Velocette)

itma · Post by **itma** » Thu Mar 24, 2005 10:28 pm

dunno alan thats why i`m asking![:)]there always seems to be someone who can come up with recondite knowledge on this site
don`t some of these belts run in oil? i`m a bit behind in modern day technology

RogerNorman · Post by **RogerNorman** » Thu Mar 24, 2005 10:46 pm

From memory Alan, from my days as a Viper owner, the pully on the 30 watt and 60 watt dynamos were different sizes on the dynamo end but I am sure either would fit inside the space left on an AMC. Mine used to get oil on it - admitedly not suturated as it would in an AMC case, but if using a Vee Belt it didn't seem to affect it whereas a flat belt would slip. Trouble is the pully was wider from memory and wouldn't fit in the normal position for an AMC set up. I'm sure wearing your Engineering Hat you will now rise to the challenge and go and start producing one to turn up at the Fighting Cocks with one fitted in the none too distant future - there's a challenge! They were certainly quieter and had the advantage that if the bike did kick back, the belt would slip against the engine rotation.

Biscuit · Post by **Biscuit** » Thu Mar 24, 2005 11:18 pm

Will it won't it will it won't. Roger mate you say in one breath the pulleys would fit, and a couple of sentences later say they are to wide. I have treated you in the past as an esteemed Club member, both at local and National level, and now you admit to owning a Vespa, oops, Velocette. When I have designed a nylon chain and faced the shock absorber cam face with PTFE, I'll look into the belt driven dynamo.

RogerNorman · Post by **RogerNorman** » Fri Mar 25, 2005 10:44 pm

Should have made the comment clearer I guess. The diameter varies but I am sure would fit - whichever size was used. The problem however may be the width of the pully but I am sure there are other pully belts on the market which could be used and would be narrower in fact I guess nowadays a cambelt type could be used. I look forward to your rising to the challenge. I'm sure if anyone can - you will.
As for the Velo - it went long before you joined the Section in fact I did a straight swop for it against the G9 one day with Ray Groves, who used to be a Surrey Section member. It was certainly still around a few years ago but it was a bit of a love/hate relationship.

doug · Post by **doug** » Tue Apr 19, 2005 8:36 pm

Ken have you considered that a bent dynamo shaft or crank shaft could cause the chain to be tight at one point and slack at another? In which case changing to a belt drive whould not solve the problem unless the belt had a tentioner of course. I don't know if it is possible to fit a chain tentioner or even if there's room. I would say if it is a bent shaft either dynamo or crank it needs to be replaced, or machined true if that is possible.

itma · Post by **itma** » Tue Apr 19, 2005 10:25 pm

yep, bent dynamo shaft sounds a good bet, every thing else new, and it fits in with the bent theme thats going on in my life lately, like my bent peugeot 505, reputedly unbreakable, unless it is on the same road as an out of control espece d`un putaine 20 mile out of calais[:(][:(!]

doug · Post by **doug** » Tue Apr 19, 2005 10:43 pm

your problem with the espece was not because you were on the same road as it, but because you were on the same part of the road that it was on. I know I've done the same thing with a lorry

Colin F · Post by **Colin F** » Wed Apr 20, 2005 8:55 am

I only know of 2 bikes that have a belt drive to an alternator, Both these bikes have a car alternator mounted up under the seat.
Malcolm Saggers has a drive off a BSA bottom end so not really relevant here.
The other one is Bill Redford and his G80. I'm sure a lot of you will know this bike. From memory this has the dynamo armature replaced with a dummy spindle with a pulley on to drive the alternator.
The down side is that the dynamo chain is still required to drive this set up.