Dynamo issue

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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FergusandTed
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Dynamo issue

Post by FergusandTed »

Hi I'm trying to align the dynamo on my model 18 I bought the bike as a collection of parts not all of them correct
The dynamo sprocket is to far away from the inner chain case even with the dynamo touching the back of the gearbox
The gearbox is a CP stamped G1G45 the Dynamo E3H I'm sure I have the correct spacer behind the engine sprocket and correct dynamo sprocket
3B4B4525-17A0-4E4A-9EF6-B64BADC94FEA.jpeg
The only problem I can see is the armature shaft seems to extend too far out the case
0495978B-7896-4DCB-B0CF-E7E0859B7CDF.jpeg
The shaft turns ok but the thread isn't great and the woodruff key doesn't fit so if I get the armature replaced will a E3H fit with the CP case
Also I've read on the forum about a dynamo alignment plate and how to fit it but I have never seen one and have no idea what it looks like could anybody post a pic please
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clive
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Re: Dynamo issue

Post by clive »

The Dynamo sprocket looks correct. There are two lengths of Dynamo. The later longer version will not fit with the CP box. If yours is the wrong type changing the armature will not fix the problem.
clive
if it ain't broke don't fix
Groily
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Re: Dynamo issue

Post by Groily »

The correct armature - Lucas part # 200802 - should be 166mm long.
Your one looks correct (it's the only one of the range that has the tapered nose and fits a short dynamo body) but is there more thread showing outboard of the locking ring than is correct, suggesting that the armature is not fully home at the brush end perhaps?
The alignment thing you refer to is an adjustable strip of bent tin which screws into the dynamo body (if it has the holes tapped for it) to stop the dynamo sliding into the primary chaincase. Not found on other marques AFAIK.
The thread would clean up OK with a 3/8 BSF die I think - if the armature actually works.
New armatures are available easily luckily, so you should be able to get to 'happy' without too much trouble.
FergusandTed
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Re: Dynamo issue

Post by FergusandTed »

Cheers Clive and Groily
Thanks for confirming it will fit, that's the main thing ( I'm no expert as you may have guessed) so I'll send the dynamo off for refurbishment
There are no holes in the body to fit the alignment plate ,I guess it's from another marquee so no need to worry about that
Thanks again
SPRIDDLER
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Re: Dynamo issue

Post by SPRIDDLER »

Alignment strip shown.
Also note that the extent of the armature protruding from the end plate is less than in your photo.
Dynamo alignment strip.jpg
Photo courtesy of Group Leader :)
Group Leader wrote:That dynamo looks terribly familiar Sprids :lol:
Alan
I assume from your subtle hint it's yours. I do collect pics from the highly skilled and knowledgeable for further reference. ;)
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Last edited by SPRIDDLER on Sun May 17, 2020 9:34 pm, edited 1 time in total.
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Group Leader
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Re: Dynamo issue

Post by Group Leader »

That dynamo looks terribly familiar Sprids :lol:

FergusandTed if you do get tempted to have a go at rebuilding the dynamo yourself (it's a great way of learning) make sure the main bearing is a good but not ridiculously tight fit on the armature. I've had two armature (from different sources) where the armature diameter was oversize. On the second re-build I learnt from my earlier mistakes and ended up having to take a skim off the shaft to get the correct fit.

http://www.jampot.com/forum/viewtopic.p ... re#p206333

Alan
1953 AJS 16MS, 1939 BSA 250 and a 1/3 scale Sopwith Triplane but that's another story ..... :lol:
FergusandTed
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Location: Suffolk

Re: Dynamo issue

Post by FergusandTed »

After reading your trails and tribulations Group Leader I'm happy not to tackle it myself so I'll call Dave Lindsey tomorrow and hopefully get it to him this week
Thanks for the guidance guys stay safe

Every days a school day
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Group Leader
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Re: Dynamo issue

Post by Group Leader »

SPRIDDLER wrote:I assume from your subtle hint it's yours. I do collect pics from the highly skilled and knowledgeable for further reference. ;)
Your first sentence is correct, I too collect reference photos when ever I come across them although in my case I'm not very good at filing them somewhere where I can find them again! One of the many benefits of good internet forums I reckon is the wealth of knowledge and visual information given freely by so many to so many :)

However, I'm not certain the second sentence applies in this particular case! :oops:

Alan
1953 AJS 16MS, 1939 BSA 250 and a 1/3 scale Sopwith Triplane but that's another story ..... :lol:
FergusandTed
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Re: Dynamo issue

Post by FergusandTed »

I case it's of interest or help to anybody
My E3H is from a mag /dynamo and would not have been suitable even if the armature was correct because there is no bearing in the drive end I'm told
I contacted Tony at TC motorcycles he was very helpful and explained the problem
He provided a reconditioned E3N with a 2 year guarantee at a very responsible price and posted out straight away which fitted straight in
Thanks for the advice and I can recommend TC motorcycles
56G80S
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Re: Dynamo issue

Post by 56G80S »

+1 for Tony Cooper.

Johnny B
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