Bosch Alternator Disassembly

I needed to clean my alternator of 32 years of dirt and grease. I took it apart, cleaned the grease from the cases,pulley and fan, inspected all parts, removed some rust from rotor, cleaned slip rings and brushes and re-lubed the rear bearing. Reassembled it then had it checked at Autozone and all systems passed.

Some observations:

I used Simple Green Extreme (aircraft version), CRC QD Electrical Cleaner spray, 400 grit sandpaper and brass brush to clean, polish and remove oxidation.

Most screws are slotted and are in very tight. Use the proper size screwdriver and go easy.

The pulley nut can be loosened as follows: After you separate the front and rear cases, the pulley and rotor will still be attached to the front half of the case (held on with the front bearing plate which is accessible once you remove the pulley). Secure the rotor in a vise (plastic or rubber jaws), now you can use a wrench to loosen the nut and then a puller to remove the pulley.

The diode assembly and stator are only connected to each other by three, large soldered wires. Handle this with care.

I did not have to replace the bearings. They both spun well. The front one was sealed on both sides. The rear one was sealed on one side and open on the other (with the balls held in by a cage) . This is the side that fits into the recess on the back case. I just cleaned out the old grease and repacked it.

The easiest part to find is the voltage regulator assembly, which includes the brushes. Brushes are also available separately and need to be soldered in the holders. Check the brush length and don't let them get too short or they will score the slip rings and then you will have to replace the whole rotor. The voltage regulator with brushes is held in with two screws and is "somewhat" accessible without removing the alternator. The round shield, held on by 4 nuts that attach to the case screws, will have to be removed, however, to gain access to the voltage regulator.

The internal parts are standard Bosch parts and used by several other cars, 95 Volvo 850 and 90 Audi 100, among others. This Ferrari alternator is 55A and other versions of this alternator may be higher amperage.

From my research, the Ferrari case is unique. Some Fiat applications also have the same three, mounting holes, but the 308 has a unique distance between the holes.

The Audi Alternator manual has some good info on bench testing as well as an exploded diagram of the parts.

Nice project for an afternoon.
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