24 volt Autolite UMB 4301 UT

Bobber · Post by **Bobber** » Sat Feb 13, 2016 3:36 pm

I've tore apart my starter, how does it look? the pinion keeper was bent up and distorted when it came out. The pinion would fall out when tilted downward when not in the motor. Other than that, how does it look? It rotated when in the motor, but not fast enough. I didn't find anything other than the keeper messed up to be wrong with it. I cleaned it up and will test the field coils and what ever the book says. Do I have enough of the brushes left? I guess it wasn't clean enough to get good contact and that was what made it so slow?

Thanks

Post by **wesk** » Sat Feb 13, 2016 5:58 pm

Brushes need replacing and commutator is in dire need of truing the surface and a new undercut of the mica. Before throwing money at the armature take it to a good shop and have it checked with a growler then while it's there get the commutator undercut done and the set of 4 new brushes run in properly on the bench.

This is how the commutator should look. The razor's edge shows the proper undercut needed.

Here's the commutator in a proper undercutting lathe.

Keep in mind these little starters run $375 O/H'd exchange.

Bobber · Post by **Bobber** » Sun Feb 14, 2016 11:27 am

I'll drop by and have it checked out.

Thank you.

Post by **wesk** » Sun Feb 14, 2016 11:39 am

Also, are you sure about the model #? Should have MBP4301UT. It would improve proper seating of new brushes and continued operation if you can find 4 new brush springs as well.