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MG Midget and Sprite Technical - Dynamo model number

Evening all, I have a 72 midget fitted with a Dynamo. Its had a chequered history, rebuilt in 1980, commutator cleaned on a lathe, new brushes and bearings etc. All perfect. It stopped charging around 1986 when the car went into long term storage (for storage read terrible decline). I'm now rebuilding the car and of course had to tackle the dynamo again. Does anyone know which model I should have? I'm trying to keep it stock so not sure if it was right in the first place back in 80. I'm not keen on remanufactured so would like to rebuild or replace with similar. Many thanks. Si
Simon Ricketts

Lucas C40 dynamo; IIRC the month and year is stamped into the casing.
David Smith

Yes, C40 it is.

It's actually the week number and year on all Lucas parts.
Dave O'Neill2

Thanks guys.
Simon Ricketts

Check your regulator box too.. I used to take mine to an 'Old School' auto electrician to have 'set-up' before fitting as a pair (dynamo and reg box).

Mark.
M T Boldry

What Mark says.

When I was a AA bod I was forbidden to fit only a control box or a dynamo alone. We always HAD to fit the two as a pair and make the dynamo live by "splashing" the field terminal on the dynamo.

Before the D and F terminals were connected to the car wiring.

Disciplinary would ensue if we didn't, not because of selling parts, in the early days of my employment we didn't sell parts via the AA.

But definitely got a Trossaching if we got it wrong.
Bill1

Well, I tackled the dynamo. Installed a complete kit, brushes, bearings etc. Cleaned polished and painted all the components and it was great for while, 30 mins, and then it went again. Red dash light on. Stripped everything again just to make sure nothing was awry. All ok.
After a search I found the article describing the troubleshooting technique for dynamos the results of which were the field windings are U/S.
I have to say that they were a bit shabby, cotton covering falling off, but connections were fine. I trimmed up the loose cotton but that was it.
So, does anyone have any other ideas? I could pick up a new field winding from eBay but none of their numbers are the same as mine. For the record mine is 22704L2 62, which I think makes it a 62 model. Can’t be the original surely.
Does anyone have a spare C40 for sale, or suitable windings, I can pick up from Hampshire, Berkshire, Devon or Cornwall areas. Yes I get about a bit.

Many thanks Guys.
Simon Ricketts

Someone who knows about electricity will help you, but how do you know that the fault is with the dynamo and not with the voltage regulator?
Guy Weller

Simon I have several dynamos in Wokingham, not expensive, and we can rummage to find one you like the look of or has the best date for you...
David Smith

Guy, I used the following to trouble shoot:-
http://www.mgb-stuff.org.uk/electricstext1.htm#nocharge

I believe its taken straight from the Lucas manual.

Results:
If the voltmeter reads 0.5v to 1v then the field winding may be faulty

It has the word 'may' so open to suggestions.

Si
Simon Ricketts

I've got a C40 marked

Lucas
6. 22765D 12/
C40 2/68

Not too sure about the "6." but I think I've got the rest of it right.
Unfortunately, I'm in Stockport, Cheshire.
However, it was working fine up to 4 months ago and if you're stuck, I guess I could remove the field windings( if not too big a job) and post those to you?
Regards,
Malcolm
M J Chapman

Many thanks Malcolm, I'll let you know if I get stuck.
Simon Ricketts

Simon your server is blocking my return email...
David Smith

Got your phone message David, many thanks. Will give you a call this evening. Si
Simon Ricketts

This thread was discussed between 07/01/2012 and 19/07/2012

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.