Hot Rods '50 Cad. starter works on bench but not in car

The starter in my '50 Cad. powered '48 Ford just quit working. It would kick in and move the engine just a little. I took it out and took it to a friend that used to run a starter/gen. shop and he went through it. It works on his bench but when I put it back in the car it just does the same. I know it is starter trouble because I took the starter out of my Cad. powered roadster and put it in the '48 and it cranks great. Just wondering where to start looking.

 

Make sure you have a good engine ground.

 

Does the same starter work in the roadster?

 

as themoose said,id say its a bad earth /ground,do you have a ground cable from engine to chassis?

 

After I put the roadster starter in the 48 and it worked as well as it had in the roadster. I put the rebuilt starter that took a dump in the 48 in the roadster and it just barley cranks as it did in the 48 before having it rebuilt. That says to me it is in the starter.

 

Gary,have you talked to your friend that went through it, to see what he has to say?

 

Ask your friend if he put new bushings in and checked for play when he "went through it".

 

It may be internally shorted. I'm assuming this is a 6V starter than has been run on 12V. Over time, the insulation can break down; you'll probably have to do a 'growler' test to see if the armature is shorted, as well as testing the field windings to make sure they're within spec. Worst case, you can have it rewound at a motor shop. It could be bushings or brushes, but most rebuilders check/replace those. Try running a load current test; a low reading could indicate bad brushes or open windings, high could be a short. I would expect to see roughly 300 amps while cranking (+/- 50), above or below that indicates a problem.

 

He did put new bushings in it and he's had it twice. Would it work like that if it was dragging?

 

i would agree it is a starter problem.
tooth count the same?

 

Tooth count must be the same the good roadster starter works just fine in the 48.

I'm thinking Steve is right It's something in the windings.

 

You can lose one field winding and the motor will still start and run on the bench; it just won't have enough power under load.

 

Thank's Steve That sounds good i'll check it out.