Commutator stones... you need them.

[pfarber]

Everyone at some point has suffered through slow starting or charging issues. These 6 volt beasties just don't leave much room for corrosion or bad grounding. While the TM does list some acceptable ways to clean the commutator, in 2012 there is a much better way to do it.. while the starter or genny is still in the vehicle:

Commutator stones aka brush seating stones or brush cleaners.

There are several products that go by this name, you don't want the one with the two separate stones on a plastic holder, you want the one that looks like a square bar about 6 inches long.

The above stone is 1/2 x 1/4 x 4 3/4

I could not find a video to show it, but the cleaning operation is simple. Just remove the brush cover and while the commutator is spinning, touch the stone to the commutator with a light pressure. You will immediately see the copper get nice and bright. On a starter you are working around parts that do have several hundred amps going through them (a starter will see just about full battery amperage).... so don't touch any wires. The stone is not conductive, but the dust could be. It only take a second. A genney has 40amps at full charge rate... plenty of amperage to make your day suck.

One more note on commutators: ONLY GENERATORS HAVE THE MICA UNDERCUT! If your starter commutator has undercut mica that can be a problem.

Beware if you buy the stones online. I was able to get a local electronics store (Moyers) to order me a box a 6 for $30. Some places charge $30 for just two so SHOP AROUND.

[pfarber]

Got the stones in. A box was $32 with tax, delivered:

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So here is a pic of the commutator on my jeeps genny. This is still mounted on the engine:

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Note the dark ring in the middle of the commutator. This is dirt/debris/carbon from the brushes. It must be removed! I unhooked the belt and turned the pulley with my hand while holding the stone against the commutator and applying a little force. In about a minute this is what it looked like:

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To quote Mal from Firefly "SHINY!'

On to the starter. I had hoped to keep the starter on the engine but the location of the brushes, springs and wires did not leave any room to get the stone on the commutator. Here is the starter off the jeep with a brush out:

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Again, note the dark ring on the commutator and the dark face of the brush. The TM10-1513 says to use #00 sand paper to clean the commutator and brushes. But I like the stones as the are finer and do both the commutator and brushes as the same time.

After about a minute of spinning the shaft and holding the stone on the commutator this is the result:

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Nice and clean! I also oiled the bushing, re-greased the pilot bushing in the bell housing the cleaned all the ground points.

My starter is again working like a charm!!!!