Precis 1988 (Bosch type)
Note: If you decide to replace the brushes (but not the entire regulator), you will need to desolder the old brushes from the regulator and solder the new ones in their place. If you do not have the soldering skills, leave this job to a qualified person. If you overheat and damage the regulator while performing the brush replacement procedure, you will have to buy a new one.
1. Remove the generator.
2. Unscrew the screws securing the voltage regulator (see illustration).
17.2 To remove the voltage regulator/brush holder assembly, unscrew the two mounting screws (shown by arrows), then remove the assembly
3. Remove the brush holder and regulator assembly and measure the brush protrusion length (see illustration). If the brush length is less than 5 mm, replace them with new ones.
17.3. Measure the length of the brushes with a ruler; if the length is less than 5 mm, replace the brushes
Note: If you are replacing the voltage regulator, skip the next step as the new regulator has new brushes.
4. Unsolder the wire connections on the brushes, remove the brushes with springs.
5. Install in reverse order. Make sure that you solder the wires of the new brushes correctly.
The rest (like Melco)
6. Remove the generator (see section 16).
7. Unscrew the bolts that connect the two parts of the generator together.
8. Wrap the front of the generator housing with a rag and secure the front of the generator in a vice.
9. Unscrew all nuts from the rear of the generator.
10. Using a 200W soldering iron, heat the rear bearing seat in the rear housing (see illustration). Carefully insert two regular screwdrivers between the two halves of the generator (not too deep or you will damage the stator) and separate the rear housing of the generator (see illustration).
17.10a. Heating the generator rear bearing seat will facilitate separation of the generator housings
17.10b. Using two screwdrivers, separate the generator housings
Warning: Perform the operation carefully, otherwise the aluminum body may be damaged.
11. Unsolder the brush and regulator holder.
17.11. Exploded view of a Metco type generator. 1. Alternator Pulley, 2. Seal, 3. Rotor, 4. Rear Bearing, 5. Bearing Holder, 6. Front Bearing, 7. Front Bracket, 8. Stator, 9. Terminal, 10. Plate, 11. Adjuster and Brush Holder, 12. Brush, 13. Brush Spring, 14. Oil Deflector (if fitted), 15. Rectifier, 16. Rear Bracket.
Note: When heating electrical parts, it is recommended to use tweezers as a heat sink. Do not heat for more than five seconds.
12. Inspect the brushes for signs of intense wear; if necessary, replace the brushes by unsoldering them (see illustration).
17.12a. If the brushes are worn to the limit, they must be replaced
17.12b. When replacing brushes, unsolder and solder the wires in the indicated places
13. When installing new brushes, solder the wires so that the limit line on the brush protrudes from the end of the holder by approximately 2-3 mm.
17.13. When installing new brushes, they must protrude from the holders by a certain amount
14. Install the brushes into the holder and secure them with pieces of wire so that the clips can be removed from the rear of the generator after assembly is complete (see illustration).
17.14 When joining the two parts of the generator housing, insert pieces of wire through the rear housing to secure the brushes in the holders
15. The rest of the assembly is carried out in reverse order.