Some notes on reworking the VW generator

To dis-assemble the generator, I loosened the two long bolts that go all the way through the generator, end to end.  I left a full thread engagement into the end cap and I broke the end cap loose buy  tapping the slotted end of the bolts.  This made a nice gap to insert a couple of pry bars in between the end cap and the generator body.  I just tapped on the end of the armature shaft with a bronze hammer until it slid out from the bearing.  I did almost the same thing to the opposite end.

Next, I released the springs that apply pressure to the brushes and I loosened the screw that connects the end cap to the electrical contact in the body and the whole assembly just slid apart.

I removed the two screws that held the bearing into the end cap on the fan end and the cap came right off.  Next I pulled the bearings off the armature shaft using a small puller.  They were not on very tight, they slid right off.

I sprayed all the parts with cleaner and pushed the bearings back on the armature.  I just reversed the disassembly process and it was back together and ready in no time.

I used a piece of 400  grit sandpaper to clean the commutator.  Make sure there are no burs left that can cause excessive ware to the new brushes.
Pay close attention to the brush spring positioning upon reassembly.  The coil spring should be positioned so that pressure is applied to the center top of the brushes.  This applies a nice straight even linear pressure on the brush so it is being pressed against the commutator.  Be sure to check the travel of the brushes to be sure they do not bind.

A couple of notes here, this procedure applies to a generator that was previously working, it just needed the bearings replaced.  The coils were fine and the generator produced power, it just had noisy bearings.

It really isnt possible for a DIYer to repair bad windings. The parts should just be replaced if that is the case.  Used parts are out there, just be sure they are good.

Be sure to polarize the generator before you reinstall it.  To do this, connect a jumper wire from the D- terminal to the ground screw. Connect a +12 volt DC source to the D+ and the D- terminals.  The generator should spin up like a motor.  Only allow this to run for a couple of seconds, that's all you need.  This magnetizes the iron/steel cores between the windings and the hysteresis in the system (trace amounts of magnetism left over in the plates) will allow the generator to produce power.  Generators that have been sitting for long periods of time will eventually loose their trace amounts of magnetism in the plates and will "forget" how to make power.  The polarizing  restores this magnetism and you are off and charging.
Good luck!