The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: Grammabud on 01.02. 2014 21:20

Title: Dynamo chain replacement?
Post by: Grammabud on 01.02. 2014 21:20
Is it necessary to remove the crank sprocket in order to replace the endless dynamo chain?  If so, does it require a special puller?

Why is the chain endless anyway???
Title: Re: Dynamo chain replacement?
Post by: trevinoz on 01.02. 2014 21:30
You should be able to remove it by rotating the dynamo until it is loose and lift it off.
Maybe it is endless because the design engineers were afraid that a clip would come off.
Probably the same reason they made duplex primary chains endless.

Trev.
Title: Re: Dynamo chain replacement?
Post by: morris on 01.02. 2014 21:50
I had to pull the crankshaft sprocket off to remove the chain on mine. No way to lift the chain over the sprocket. It wouldn't pass between the sprocket and the case.
I used a small bearing puller over the sprocket with the chain on (in case something gets damaged it will be the chain not the sprocket)
This was before I converted to belt drive which is an option sure worth to consider.
The belt pulley has two 1/4 ww threaded holes to get it off the shaft without a puller, and the small pulley is threaded inside to pull it off easily.
It also makes your dynamo spin 20% faster, so makes for a better charge, and if the belt lets go, it'll sure make less damage than a chain.
I am thinking along the same lines as you Trev. A clip on such a flimsy chain could easily let go.
Title: Re: Dynamo chain replacement?
Post by: WozzA on 02.02. 2014 02:17
as Trev said... I just rotated the dynamo to slacken the chain to remove & replace it...
Title: Re: Dynamo chain replacement?
Post by: RichardL on 02.02. 2014 02:40
Look closely fo the removable-link retaining clip. It's small and might be ovelooked. .
Title: Re: Dynamo chain replacement?
Post by: Grammabud on 02.02. 2014 03:32
The chain was broken when I bought the bike.  I purchased a Reynolds replacement.  It has no master link.  Like MORRIS, There is insufficient space between the crank sprocket and case to install the chain.  At least on this bike the sprocket will need to be removed.  
I don't understand why some are different.
Title: Re: Dynamo chain replacement?
Post by: KeithJ on 05.02. 2014 10:22
"I don't understand why some are different."
Perhaps to do with the type of machinery they were made on and methods used.  When casting crankcases wooden patterns are used.  From time to time they need to be refurbished and hence the moulds produced may vary.  Don't forget these were made in the dark ages when investment in modern machinery was not in vogue.
ATB
Keith
Title: Re: Dynamo chain replacement?
Post by: bsa-bill on 05.02. 2014 11:09
I agree with Keith

the inner case partition webs differ in thickness
Title: Re: Dynamo chain replacement?
Post by: townsends20 on 05.02. 2014 21:45
Why replace the chain when you can convert it to belt (no noise, no rattle, and no damage from a slack or broken chain)
    Steve.
Title: Re: Dynamo chain replacement?
Post by: duTch on 06.02. 2014 09:45

 Hey Morris,
 
Quote
I had to pull the crankshaft sprocket off to remove the chain on mine.
,

 I'm sure you meant 'drive Sprocket', as this is not on the crankshaft...?

 I have the SRM belt conversion, but still had to relieve the casting to accommodate the drive pulley...... :!
When I remove the pulley/sprocket, I slip a chock (thick enough to take up end float) between it and the case and after loosening the nut give it (idler shaft stub) a sharp rap with a 'drift and hammer' - should jar it from the taper.
 I also think the nut only needs to be tight enough to stop the pulley from slipping, it doesn't load up too much...??
Title: Re: Dynamo chain replacement?
Post by: morris on 06.02. 2014 19:43
Quote
I had to pull the crankshaft sprocket off to remove the chain on mine.
,

 I'm sure you meant 'drive Sprocket', as this is not on the crankshaft...?
Right.....sorry *eek*
Title: Re: Dynamo chain replacement?
Post by: duTch on 07.02. 2014 12:51

 's ok, no need fer 'sorry', am not pickin' on you...... *beer*
Title: Re: Dynamo chain replacement?
Post by: morris on 07.02. 2014 17:24
I know you didn't, I just want to get the facts right.
Cheers ;)