Dynamo strip.

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MalcW
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Posts: 626
Joined: Tue Oct 24, 2017 12:05 pm
Location: DEVON UK

Dynamo strip.

Post by MalcW »

Hi, the E3L dynamo on my 1960 twin has oil in it, courtesy of a failing oil seal. I've removed it from the bike, taken off the drive gear, Woodruff keys and washers, both brushes and springs and the two long through bolts. The end plate at the brushes end has moved very slightly, but that's all. I don't want to force anything. Is there something else I need to remove, or do I need to get the mallet out?

Thanks,

Malc
Groily
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Joined: Thu Jul 04, 2002 1:00 am
Location: NORMANDIE FRANCE

Re: Dynamo strip.

Post by Groily »

The brush end needs easing off the armature, with the small ball bearing complete on the shaft. As that bearing's a good fit in the housing, it may need a bit of a gentle tap or levering to get the alloy housing off. But be sure not to trap a field coil wire as you do it - they can be a bit tangled sometimes.
You can do it by pulling off the drive end complete with armature, often just as easily. The little bearing may have a small circlip outboard, which would have to come off to replace it, or an axial screw (and washer maybe) holding it on. But there's nothing to impede withdrawal of the armature or removal of the housing except the fit of the bearing race and the 'maybe' of field coil wires getting jammed. (Worth noting which field coil lead went to F and which to the earth screw (along with the earthed brush), for when you reattach them. An error there (or with which brush is attached to what) will change the direction of rotation of the dynamo.)

At the drive end, the armature is a tight fit in the bearing and will not usually slip out easily. It probably doesn't need to come out, unless there is any wiggle.
The collar on which the oil seal runs will probably be threaded or could (maybe) be a plain push-fit one. It needs to have an unblemished outer surface, or the new oil seal won't seat nicely or last very long . . . . Mole grips, steel vice jaws or pliers are therefore bad for getting the collar off!
g5wqian
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Joined: Wed Nov 18, 2015 7:43 am
Location: wiltshire
Location: near swindon wilts

Re: Dynamo strip.

Post by g5wqian »

mine came apart easy enough , there is a screw and washer on one end of the armature shaft that needs taking out at the small bearing end .

the only difficult part is removing the small ballrace as you need to make sure you dont damage the thread inside the end of armature , i have a puller which has screws to tighten that grip on the outer of the ballrace but i made a small plug of brass to sit on end of armature shaft so that the screw in the puller pushes against that plug instead of trying to work its way into end of the armature shaft .

all you need to clean the internals of the dynamo is a can or two of brake cleaner and if possible some compressed air to blow it out , then somewhere warm to dry it out , i dried mine in front of a halogen heater .

you can get the cork seals for the dynamo to timing case from the club spares and the lip seal is easily obtainable along with bearings if reqd , brushes are also easy to get .

dont forget to watch out for the shim washer if there is one , under the bearing on the shaft .

the lip seal taps out easily .

just need to be a bit carefull with the dynamo gear and woodruff key on assembly , not to lose or cause damage to the key and slot when putting the gear back on .

dont tighten the draw bolt in the timing case too much , it has only got a small thread in the dynamo casing , best to just pull the drawbolt lightly in and push the dynamo up and to the timing case with a bit of wood and then tighten the strap up and then nip the drawbolt up lightly .

i used welseal on the cork washer and it sealed nicely after leaving overnight to cure .

when you run the engine up , if youve put new brushes in , you may find it needs running a few seconds at up to 1700 revs before the dynamo shows charging .
mine tends to cut in at about 1200rpm if it has no load on it , but if it has a headlight load it tends to function from idle looking at the ammeter .

you probably wont need to flash the polarity .

to test the dynamo is working before re installation to bike if you connect a voltmeter that is set on its lowest range [ maybe 1 volt range] across the terminals and turn the armature by hand you should see a small deflection on the meter reading , an analog "needle" type meter may be more usefull in this respect.

cheers
ian
MalcW
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Posts: 626
Joined: Tue Oct 24, 2017 12:05 pm
Location: DEVON UK

Re: Dynamo strip.

Post by MalcW »

Thanks chaps

I'll follow your advice and see where I get to. I've ordered a replacement cork gasket (mine came off in 2 bits), a new oil seal, and a new tab washer for the drive gear bolt. Oh, and a new oil tank cap, to replace the one that went walkabout on Sunday.

As long as I have it back on the bike ready for the bank holiday weekend I'll be happy. If it isn't charging properly I'll see where to go next, but at least I'll be able to ride the bike.

Cheers,

Malc
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