Snapped Primary chain.

[dave16mct]

Another solution could be to remove the dynamo altogether. Using LED's throughout and a good battery could be an alternative. Now that good headlight LED's are available I'm considering going down this route on my next project.
Dave

[MrB]

Firstly many thanks for Groilys reply, very informative and it has helped me dig a bit further as to what I actually have dynamo wise. I have scraped the paint off the main body and wire brushed till I have found some numbers. visible is 3 H M - L O also 200286. Its very faint but its there. I suspect its not off a G80.
The bits and bobs I have found so far is it looks to be BSA and had a gear originally on the shaft. So, and I agree it is a solution from Daves post is to just use the Dynamo as a ornament as I already have LED lights or if someone has the correct dynamo for sale I think I need to buy a replacement.

[Groily]

Yup, bit of a mish-mash I think. E3H M is for a magdynamo, so you are right, not originally from a G80. It would have had - originally - a parallel shaft on the drive end for a pinion, and a bearing retainer plate that was triangular, to mate with the aperture in the magdyno casting. So, not correct, although some mix 'n match could have made it OK. Sadly, if the end's been chopped off . . . .
But don't throw it out - the bits are good for someone, and new / correct armatures can be got, so it could be restored to health and even to AMC single spec, if anyone wanted!
Dunns Dynamos would probably have what you want, if you want to spend the ££, as the E3N isn't rare (until you want one - of course! - when they become rocking horse poo). But LEDs are quite adequate for a lot of us these days, as night riding for hours on end isn't a big thing really.

[MrB]

Thanks again , I shall contact Dunns tomorrow for a price. Then probably decide that bolting the old one back in without the chain or sprocket on and charging the battery beforehand ,whilst spending the saved money on fuel and enjoy riding it as much as I can.

[Chazzyb]

Long dynamos won't fit CP boxes but you can get them in on the GB box (B52)

I can confirm this. My 18S with B52 box has an E3L dynamo fitted, with a keyed, tapered shaft and bolt fixing.

[MrB]

So although I have bolted it all back together and gone for several pootles without the dyno successfully , I have managed to bag a correct second hand dyno from ebay. Now does anyone know what size woodruff key it takes ? and whilst it came with the bolts to secure the locating plate, I don`t have the locating plate. Any ideas on sizes as I will make one.
Cheers

[Pharisee]

Long dynamos won't fit CP boxes but you can get them in on the GB box (B52)

I can confirm this. My 18S with B52 box has an E3L dynamo fitted, with a keyed, tapered shaft and bolt fixing.

I think it may depend on which end cap the dynamo has. My '55 M18S had a long dynamo fitted when I bought it. The had the plastic end cap with the metal band around it and plug in wire connection. It would only just fit with the gearbox adjusted fully back. That meant that you couldn't adjust the primary chain. I have it on good authority that long dynamos with the pressed steel end cap and the grommet in the side for the cable can be used and allow limited gearbox adjustment.
Better option is to use the correct short dynamo.
John
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Long dynamo...
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picture29.jpg

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Short dynamo...
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picture34.jpg

[dave16mct]

Here's a drawing of the dynamo locating strip:
http://archives.jampot.dk/technical/Do- ... guess).pdf
Dave.

[MrB]

Thanks for that Dave.

[Chazzyb]

Here's the end cap on my E3L. It's still snug.

Dynamo Cap (Small).jpg