Starter bench test spins slow
 

The starter on my 29 was spinning slow. 6 volt battery and all connections were fine. I installed my spare starter and everything is fine. Now I need to fix the slow starter. I disassembled the slow spinning starter and the only thing that I noticed odd was the insulation on the insulated brushes was falling off. One of the insulated brushes had pretty shinny wire where the insulation had fallen off, maybe it was shorting there. Is there a good tutorial online for starter component testing and inspection? What could I use to replace the insulation on the wire for the brushes?

Re: Starter bench test spins slow
 

The armature may be dragging on the field shoes .

The rear bushing in the starter is under strain.

The rear bushing is usually the first thing to go .

If the rear bushing is worn enough the armature can drag , causing the starter to spin slowly .

Re: Starter bench test spins slow
 

I have made starter/ generator fabric insulation out of outer covering from shoelaces, wrapped some thread around the ends with dab of glue to prevent fraying

Look at the armature and pole pieces to see if there's signs of rubbing--- due to worn bushings, or loose- mis positioned pole piece

Re: Starter bench test spins slow
 

Guys, thanks for the input. The bushings are tight enough and the only thing the looks like rubbing are the wiring for the brushes. They may have been polishing the end of the armature. See the discoloration of the twisted wire.
Attachment 410349

What do you think?

Re: Starter bench test spins slow
 

I have used Plasti Dip brush on electrical tape to replace the insulation on generator wires. It should work ok here too I imagine.
SAJ in NZ

Re: Starter bench test spins slow
 

I am going to look into that.

Re: Starter bench test spins slow
 

My local parts house had Blue Magic brand. I’m going to try it.

Attachment 410385

Re: Starter bench test spins slow
 

I do my own starter conversions when I go 12 volts. That means insulating wires inside. I use strips of fabric covered in silicone. Once wrapped on and held in place for a while, the silicone cures and I have an insulated wire. I have 4 MOdel As all done this way and have done the same for others. There has never been a problem.

Re: Starter bench test spins slow
 

I figured out the problem. The brushes were loose on the field coils causing them to get hot and turn color. Quick disassemble, clean up connections, install heat shrink tubing and reinstall brushes. Spins like a mofo now.
Thanks for all the help.