Sunbeam Talbot 90 starter motor issues

[Martinwilliams123]

I’ve purchased my first restoration project, it’s a Sunbeam Talbot 90 1952. It’s in good condition for the year but I’m having trouble with the starter motor. It’s a Lucas M418G 25521D. I’ve removed it and stripped it down as it was turning slow. Can’t see anything wrong and brushes look ok. I’ve rebuilt it now but I’ve got a short across the power terminal and body. I stripped it again and removed the body and still got short. Can anybody enlighten me? I don’t understand why the power terminal is connected to the magnet which is screwed into the body?
Also anybody know where is the best place for buying replacements etc for this car?
Is there a equivalent type starter motor or a modern one to use instead. Thanks

[Martinwilliams123]

The code is different. The M418G is correct but the next number is different(25521D) do you know if that would make a difference.

[NMNeil]

Cross reference chart
http://www.classicvehicledata.com/wp-content/uploa...
Or rebuild the starter again.
http://mgaguru.com/mgtech/books/wsm/wsm_n_electric...
If you look at N7 and the terminal part G, it looks like there may be an insulator that goes over the terminal stud. Did you leave that out by any chance?

[Martinwilliams123]

No it still showing short when removed from housing

[Martinwilliams123]

Thanks for the info, it still showing short when removed from housing.

[Allan L]

This may seem silly but how did you find (or measure) the short?
If you used a multi-meter the normal internal resistance measured would be quite low. I can'r remember how low, but low enough to permit 12v to use several hundred amps.

[matchmaker]

Allan L said:

This may seem silly but how did you find (or measure) the short?
If you used a multi-meter the normal internal resistance measured would be quite low. I can'r remember how low, but low enough to permit 12v to use several hundred amps.

Good point. Ohm's Law applies. V=IR where V is voltage, I is current and R is resistance. Say V=12v, I=200a, then the resistance will be 0.06 ohm which will be hard to measure as it is so small.

[jet_noise]

How did you decide it was the motor, and not, say, battery or wiring?

[Konrod]

Is the car a positive earth? If so that may explain why the power connects to the motor body.

[matchmaker]

Konrod said:

Is the car a positive earth? If so that may explain why the power connects to the motor body.

Unless it has been converted, it will be positive earth, but I don't think that makes any difference to the connections.