Toehead

My voltage regulator seems to be on the verge of crapping out, so I am taking this oppurtunity to rebuild my spare 108 A alternator from an 86 firebird. Does anybody know where to get a bearing rebuild kit,brushes, and a new voltage regulator? I searched, no luck. Alternatorparts.com doesnt seem to stock any parts for the 108 A model. Thanks
-Toehead

Vader

The brushes are standard (Wells RX130 or equivalent). The front bearing is a Fafnir 203PP or equivalent. The voltage regulator is a standard as well (Wells VR723 or equivalent). Any parts house should have or be able to get those for you. The rectifier bridge is also a standard parts item. The only trouble you might have is with the rear roller bearing, but those rarely fail, and can be cleaned, lubed, and reused 99.99% of the time. .

Toehead

Thank you Vader.

Toehead

Ok. I have both alternators apart... They are a year off and there are some differences between them. For instance.. my 85 utilizes a wire wound resistor between 2 terminals of the voltage regulator, wheras the 86 does not.


IN any case.... The resistance of the diodes is also different. On my 85, all three are about 7k ohms one way, infinite the other. On the 86, one is 9k, one is 10k, and one is 11k ohms and infinite the other. Which rectifier should I use? Please respond ASAP, I have work at 4

Edit-
The one from the 85 has a blown regulator. should i still use this rectifier

Toehead

I decided to use the 85 rectifier assembly, because the diode resistances were more consistant and it appeared to be in better physical shape (no corrosion, ect) Got it back together, in the car. start it up, check the voltage. 14.6 at idle. Good. Switch to VAC. .021 volts. Good.

One annoying thing. When I stand outside, the alternator makes a whine noise, mirrored in my speakers. The whine was always present in my 85. The physical whine isnt any louder or quieter now that I rebuilt it, but the speaker whine is MUCH LOUDER.

What do you think I did? Also, i'm not sure wheter or not I got the two connections on the side in the right order. What would happen If i mixed up the low charge light (i think) wire and the output voltage to the regulator wire?

Toehead

Update- Took the car for a drive, noticed a few other things.

In gear only the speakers buzz loudly after 1/4 throttle. Up until a quarter throttle, silent. Over, and the speakers buzz. In park, I can free rev the engine without any buzzing.

The voltage with all accessories on also is still killing the alternator When I first turned it on, I could turn on all the accessories and the voltage would be constant. After the drive and the car was warm, the voltage would remain fairly constant with every accessory turned on, up to a point. Sort of a "straw that broke the camel's back " type thing. This is why I rebuilt the alternator in the first place. It will be fine, then all of a sudden, battery voltage only.

The only parts that were reused from the bad alternator were the rectifier assembly, that little condesnsor looking thing (current smoothing? ) and all the windings. What is the most likely culprit, seeing as the car isn't leaking AC ripple voltage. Im stumped.

Toehead

Replaced the rectifier with the one from the 86, all the buzzing in gear and hot voltage drop went away. I guess the recifier is bad, but only shows symptoms when it gets hot.