Rebuilding a starter

The 600 Ford with 12 volts has turned the engine very fast all along until it didn't turn at all one day. After removing the band covering brushes,I can see that all brushes are worn out and one is worn so bad it's falling out of holder between commuter and brush holder. I am considering one of the $16 brush,clip and bushing kits available from YT parts. As might be expected,the commuter is burned and pitted. Is it mandatory to turn the commuter or is sanding sufficient? If sanding,which should be used, crocus cloth,emery cloth,sand paper or wet-dry sandpaper? Back when generator were common, I've heard yea and nea on all of them,because of grit imbedding into the copper and/or conducting electric current.I suppose the conductivity issue would be easy enough to prove or dis-prove with an ohm meter but grit imbedding is not so easy. Then there's the question of how succesful shade tree rebuilding really is. I haven't dealt with a starter or generator failure in 50 years and back when I did,there were helpful one man repair shops on every street corner. I bet dealer mechanics have never heard of a growler,much less know how to use one.

Look very close at armature and and commutator. I had a starter rebuilt recently, had to replace whole unit. NAPA couldn't come up with a replacement in any of their warehouses and suppliers. Found a back yard shop that rebuilt my starter, with new armature in a couple days, including ordering and getting new parts. If your commutator is shot, good chances armature is shot as well.

There is a place in Kalkaska that rebuilds starters and he has everything under the sun and the price is not hard on your pocket. I think he has starters and parts there for stuff that has not been around and 70 years

I have never heard of turning a commuter. I was taught in trade school to use crocus cloth, the finer the better. By using fine crocus cloth it will help eliminate the grit embedding issue because the girt is so fine and it does not leave large scratches which could affect conductivity. After you sand the commuter take a pick or a small flat blade screwdriver and clean out the grooves in the commuter. By the way you describe the starter I would not be afraid to try rebuilding it. Now if it was starting to give you fits or getting progressively slower, then I would lean towards a new or reman starter as the armature or field coils may be starting to go. HTH

I always turn the commutator as I often find a low spot. Gets them round & straight again. Then check it on the growler.

Look closely at each individual bar on the commutator. If one or two have been arcing that is a sign of a open or partially open circuit which would be the solder between winding and bar. If it has that your armature is pretty much shot. Nearly impossible to test for a open without specialy test equipment unless completely open which is highly unlikely. If just even blackening all the way around it is due to poor brush contact. That can be cleaned up with a medium grit sand paper. We used to have a special roll of armature sand paper but in later years the suppliers quit offering that and we just used regular dry , maybe 150 grit paper to start and finer to finish. Does it imbed, well, some but it has worked for years doing it that way. If deeply grooved, it should be turned on armature lathe. One other thing is that after about 50 years, about in the 60's, Delco Remy FINALLY came to their senses and quit undercutting the mica on armatures.

Other manufacturers (Autolite for one) had been NOT cutting the mica forever. If armature was undercut and you don't remove enough material to completely eliminate the groove, you will have to clean the grooves so no contact is made between each bar. A starter commutator is not nearly as fussy for getting it perfect like a generator because of the relatively low speed it turns and brushes can maintain good contact. I no longer have access to a armature lathe so I have improvised other methods for the few starters I have repaired recently. I do have a growler though.

Bushings are very important in a starter along with brush contact. Go for it.

The commutator can be turned on a plain old engine lathe too. A little more setup time than a dedicated armature lathe, but it works.