AJS & Matchless Owners Club

I was under the impression that the later dynamos were a larger diameter and wont fit my mounting plates or is that wrong?

I believe that they are all the same diameter. There are two different lengths, though. I needed a dynamo for my G3/LS and I bought the longer E3L version that has originally been fitted to a BSA A10. The longer version is more readily available as they were fitted to many makes and models back in the day. The front mounting plate was different but they are interchangeable and the correct mounting plate was obtained from a supplier on eBay.

Whatever is fitted will need the correct bearing retainer plate at the drive end, and these vary according to fitment.
All E3s whatever length are 3" diameter with offset armatures.
Long E3Ls won't - I think - fit (or fit easily) with the CP gearbox, but others could confirm.
The E3AR is, as someone implied, probably the worst of the lot with the brush end bearing supported in the end cover and a non-detachable brush end, but E3N will go straight on.
If the little strip of bent tin on the outside of the dynamo, which stops it migrating into the primary chaincase, is required, some holes may need drilling and tapping in the body of a non-original fitment instrument to hold it.
There are lots of small differences between the various 'short' versions including - most important - the shape of the drive end shaft of the armature (tapered or parallel and keyed) for attaching the sprocket.

Interesting info so thanks to all. Will definitely keep an eye out for an E3N in future but as I have a new armature I'm committed to getting my old unit build. Only option I see working at this stage is the blind hole puller. Don't have one but there are cheap kits out there.

ELPS wrote:Interesting info so thanks to all. Will definitely keep an eye out for an E3N in future but as I have a new armature I'm committed to getting my old unit build. Only option I see working at this stage is the blind hole puller. Don't have one but there are cheap kits out there.

I was thinking about this some more last night, another option (which might work) is to freeze the bushing so it shrinks and pulls away from the bakelite bearing seat, you could do this with canned air (or even canned butane -- but do it OUT SIDE in a well ventilated area).

The idea would be to warm the bakelite housing while pouring / squirting in the liquid into the fitting hole. If you're lucky, it might shrink that fitting enough that it just drops right out of the bearing seat. I've used such tricks in the past for similar types of removal/installations.

Also regarding the blind hole bearing puller, here in the states a lot of the auto parts shops will rent you the tool for next to nothing, so you might consider ringing your local auto parts store and seeing if the same deal can be had.

Good luck and remember, if you do manage do destroy the bearing seat, your local machinist can probably make a whole new cover for you if it comes to that

I just did mine not long ago. I drilled two small holes 180 degrees apart in the back. Just large enough to get a punch in and slowly punched the bearing out. It cam out without any problems. When I put the new bearing in I merely sealed the two holes with a sealant (could seal it with anything). It all worked a treat

Just wanted to finish off by saying I got the bearing shell out. It wasn't easy. I purchased one of those blind hole puller kits. Initially I didnt think it was going to work as I could not get it under the shell but I ended up scrapping away some of the bakelite around the lower edge and manage to get the remover started. Still took a fair effort to hammer the bearing out but all good now. Cheers

I have not tried this but I would try finding a big bolt with a thread which just start to screw press fit into the inside of the old bearing you are trying to take out. Spray some penetrating oil on the outside joint first of all. Leave for a couple of hrs, then gently screw in the bolt. Once it has gripped on a few turns then pull. I sure purists will wince at this approach and, like I say I have not tried it myself- so your are your own! - but it might work

ELPS wrote:Just wanted to finish off by saying I got the bearing shell out. It wasn't easy. I purchased one of those blind hole puller kits. Initially I didnt think it was going to work as I could not get it under the shell but I ended up scrapping away some of the bakelite around the lower edge and manage to get the remover started. Still took a fair effort to hammer the bearing out but all good now. Cheers

Glad to hear it worked out bud.