Bosch 120A Alternator Rebuild!　2006/01/28 Related Vortex Forum
When I looked for the rebuild parts for the bosch alternator before, I could get only IC boltage regulator(see this page). This time, I got all parts which are necessary to rebuild in the Japanese Bosch dealer.


Rebuild Parts.

Bridge Rectifier（Diode plate） Bosch＃1 127 319 738 129 dollars.

Carbon brush for IC boltage regulator 7 dollars.

Fitting ring for small end bearing Bosch＃1 120 591 103 2.6 dollars.

Bearing 6303VV 6203VV 9.6 dollars.
I got this 120A alternator from 93 Golf VR6 parts car. That doner car's mileage was only 40,000 mile. mine? about 100,000 mile. :D

Very good condition.
BOSCH# 0 123 510 005

VW# 021 903 025 B

To order this part, the Bosch number is very important. I ordered it at the Bosch number and got it the next day.

I could not get them at the VW dealer.
The VW dealer only sale the rebuild one.
about $750! now! Crazy expensive.
Loosen three screws and remove rear plastic cover with pushing three lock tabs on the side of the cover.
Loosen two screws of the IC regulator and remove the IC regulator.

Next, loosen three screws of rectifire.

If you want only replacing the front and rear bearing, you don't need this work.
Crimped terminal of the stater coil wire..
How to remove ........
Broke the terminal by using the diagonal cutter pliers at six tarminal.

Work carefully so as not to break stater coil wires.
Check slip rings and contact terminal of IC regulator. A slip rings is quite worn.
Removed rectifire.
Loosen the four Phillips bolt head screws located around the outer perimeter of the rear case.
Using a flat head screwdriver and turn a screwdriver carefully at four sides.

I needed power hardly.
Done
Shaved and clean up the slip rings and remove any oxidation of the voltage regulator contacts face.

I shaved the slip ring by the flat file.
Replace the fitting ring to new one for new bearing.
I painted the steel core of the stator coil, Because the core was rather rusty.
Remove 24mm pulley lock nut by the impact wrench.

Or you will use the VW's SST.
Four screws can be accessed when removing a pulley.

The screw is fixing the cover of the front bearing.

This screw removes using the impact screwdriver because it is difficult for it to loosen.
I useed the press machine for press out the front bearing w/ the thrust washer. Easy way!
Rotor. a little bit rusty.
The bearing retaining plate fixing the front bearing to the front casing.
In my first plan, I should polish it to bling bling.

However, I painted it to silver.

corner cutting work! :-P
Remove the rear bearing by puller.

Be the most careful of this work.






Attach the push bolt of the puller to the steel shaft of the rotor.
Never attach it to the slip ring.
Because the slip ring part made by the resin, I guess that it's break easily.


If you need the slip ring repare parts, check this out. Wood Auto Supplies
All stuff.
Reassemble!

I used the bearing heater to install bearing easily this time.
However front bearing didn't need it.
Because the bearing should be inserted in the front case like this.
Install the bearing retaining plate.
Install the rectifire.
Crimp the stator coil wire and the rectifier terminal.
Carbon brush of the IC regulator.

I saved by about 80 dollars.
But, that replaced work is very difficult. Brush wire is crimped and soldered. :(
Pulled out wiring and make a hole to the brush holder with the drill.
Reassemble carbon brush to the IC regulator.
Soldered.
Installed.
Re-installed the pulley and thethrust washer.

The reassembling complete.
I bought a rebuild part at this shop.

Okada firm
2006/01/29

Instlation

The alternator is completely exposed to view because my C doesn't have an air filter box.

But, I worried about them, there is not an enough room to take it out.
The side member blocks an escape route.
I set up an engine jack to engine bay, and loosen front engine mount nut. and jacked it up.
Release the serpentine belt tension by tightening down the tension release bolt. Remove the belt and tensioner.

However air filter box bracket obstructs the work.

My C doesn't need that bracket, I bended it by the hammer. :-P
Fist of all, disconnect battery ground terminal.

Loosen B+ terminal and remove wire.

Disconnect the D terminal connecter.

Loosen wire bracket 8mm nut.

Sorry that red wire is additional direct battery wire. Generally, C doesn't have it.
Remove two 13mm mounting bracket bolt.

An alternator doesn't come out to straight.

I was very much troubled to take it out.
Rebuild alternator and Old one!

Beautiful! :D
Re-install the alternator into the vehicle.

The alternator became very quiet and made 14.5 V voltage generate.





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