Starter sluggish, time for rebuild?

[ArtB]

The original 1109611 6V Starter on 55 Lo-Boy is sluggish, barely turns over with a new fully charged 6V battery, yet spins right up with a 12V battery. Disconnecting the wire to the starter switch and applying 6V power directly using a heavy-duty jumper has the same result, ditto for 12V. Removing from tractor and bench testing gives the same results. Time to strip down/rebuild?

[Jim Becker]

It probably needs a new set of brushes, maybe bushings too. Replacing those parts is not beyond typical DIY abilities. Take the band off and have a look.

By the way, the "9G 9" on your tag is a date code. It decodes as July 9 and some year that ends with a 9, probably 1959. So you have the original type starter for a '55, but it has been changed some time in the past.

[ArtB]

Thanks for all the info, parts have been ordered.

[Jim Becker]

Don't know your knowledge level on starters/generators. You will need to clean up the commutator and undercut the gaps between each segment. If you are unsure about what is required, ask.

[ArtB]

Opened it up, this is what I've found.

[Matt Kirsch]

Yeah, that commutator is pretty chewed up and really should be cleaned up on a lathe, then the mica in between each segment undercut as Jim said above. If you don't have a commutator lathe or know someone who does, try to find a local automotive electrical shop.

Just throwing new brushes in will make it worse because the commutator is all grooved up. Smooth brushes will be making less contact than the existing brushes with the matching grooves worn into them.

[Jim Becker]

Yes, what Matt said. It looks like it has had water standing in it, probably didn't destroy anything. Blow out whatever loose material is inside the shell and stuck to the armature. Avoid damaging them, so don't go crazy cleaning them. Clean the areas of contact on the end plate, shell, and nose piece so there is good electrical contact between them. Put new brushes in, making sure all the electrical connections on the end plate are clean. Put in 2 new bushings for good measure.

[ArtB]

Cleaned up the armature, brushed and blew out the body, and installed new brushes, the bushing IDs matched the new ones so I left them in place. Reassembled, and bench tested, it spun up quietly and smoothly. Reinstalled, tractor starts first pull each time now using only the 6V battery, Thanks again for all the advice.