Dynamo Rebuild

[laxy]

What am I talking about? Of course a K2F is a magneto.
the dynamo is of course an E3L.
There is no excuse for this schoolboy error and I hang my head in shame.

[Biscuit]

Laxy you should berated me for picking holes, will I ever learn.

Well we have a mystery Don, I have had three armatures in my twin over the last two years, removing and re-using the bearings each time.
The first, 'original' armature spread it's commutator segments in a delghtful pattern inside the cover, surprisingly with no peripheral damage. The new armature lasted just on a year when six or seven commutator segment went high resistance one to the other. Jim replaced it and it been OK since. Neither of the three had a circlip, or indeed a groove.


Could it be that mine were all pattern items and yours perhaps were originals?

[Don Madden]

I have my duff ones thrown into a box for future rewind or disposal. I think all or most of them have the lucas part no. stamped in so I suspect they are original.

I did not remove the bearing from all of them as some were noisy, so cannot say if those have the circlip.

Mystery, indeed! Perhaps the ones sent to California have extra hardware knowing they would be abused.

Cheers, Don.

[RogerJ]

I have just had cause to replace an armature on a E3N dynamo - and that had no screw but what did appear to be a groove for a circlip of some sort (also missing!).

I noticed that there is also a spacer below the bearing and then a thin "paper" washer either side - were these just to stop grease from the old style bearings getting into the gubbins?

The Lucas parts diagram also refers to a felt bearing washer and cup for the same - were these also for when the bearing was not sealed?

Lastly - does anyone know what the size of the screw is that will fit the replacement armature (as discussed previously)?

Thanks, Roger

[Biscuit]

My one is 2BA.

[RogerJ]

Thanks Alan.

Roger

[Don Madden]

The E3L dynos I have worked on mostly had the small spacer, the cup washer & a ring shaped felt, which goes next to the bearing.

And maybe I don't have all the grooved shafts. Thought perhaps I had another short circuit in my brain.

Cheers, Don.

[Rikki White]

I’m happy to report that everyone’s advice and some beginners luck has enabled me to dismantle my Dynamo without any problems and surprisingly without the use of any hammers. Everything unscrewed okay, and a 6” bearing puller made releasing the armature from the large drive side bearing quite easy.

I‘ve checked the armature on the lathe at work and much to my relief it runs true, I’ve also lightly skimmed the commutator segments as suggested, the depth of the grooves is fine and it now looks as good as new. The large drive bearing feels a little rough but the small commutator end bearing is fine. Its held in place with a small wire clip and not with a screw as shown in the service sheet and as Don mentioned it’s very awkward to remove.

As well as the bearings, brushes and brush plate, I’ll need to replace the oil seal in the bearing retaining plate as it’s hardened. I’ll also replace the spacer that it mates with as the seal appears to have worn a groove in it (or should this be there to support the seal lip?)

As I couldn’t find any reason for the armatures reluctance to rotate I’ve re-assembled it with the original parts to try and understand what’s going on, but much to my surprise it now rotates freely!! So I’m not sure what the problem was, maybe the large bearing wasn’t seated properly but thankfully it seems fine now.

So I’ll carefully dismantle it again and order the parts I need and re-assemble it for the final time hopefully when they arrive in a week or two. I’ve taken quite a few of photo’s and I’ll be happy to forward them on to anyone that may be interested (Keith would they be of any help to you).


Many thanks again Don, Biscuit, Lawrence, IoIski, Keith, Johnny, 56G80S, Duncan, Roger and everyone for your help and advice, this has been a great introduction to using the club web site and getting more involved with the club.

Rikki

[itma]

A word of advice re brushes, some replacement ones seem to be made of soot and wear out within hours.
try and get hold of something like old stock starter motor brushes and file them down to suit, folk don`t realise you can solder the tail leads to carbon brushes either

[Biscuit]

Ken, I have read somewhere that car dynamo and starter motor brushes are much harder than the motocycle examples, and wear the commutator quite quickly.