Author Topic: Alternator rebuild  (Read 133 times)

Josh78T/A

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Alternator rebuild
« on: October 05, 2017, 04:04:33 AM »
How many have rebuilt their own alternators? Where is the best place to get the parts to do it? I know they are cheap enough to get a replacement but I wanted to do the one on my son's as a project with him.
His is a 1981 Firebird Formula.

Thanks in advance.

Warren Seale

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Re: Alternator rebuild
« Reply #1 on: October 05, 2017, 11:52:08 AM »
The alternator is known as a 12SI and they are easy to work on.  You can easily find parts by doing an internet search.  My experience has been the diode trio fails or the brushes wear down to the point where they no longer make contact.  The brushes, diode and voltage regulator can be found in a kit that costs about $10.  My alternator is still running on the original bearings.  It has 117,000 miles on it.  The bridge rectifier is very robust and heavy duty so I would not expect it to fail.

Here is a link that shows how to rebuild them.

https://www.youtube.com/watch?v=NWMANjkgtFw

Warren
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firebirdparts

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Re: Alternator rebuild
« Reply #2 on: October 05, 2017, 01:15:23 PM »
I never do would do a full rebuild because they just don't require it, and why would you bother anyway.  Typically what I have replaced on them was the diodes and voltage regulator.  The parts used to be common at any auto parts store, but these days I think you would have to mail order.
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Josh78T/A

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Re: Alternator rebuild
« Reply #3 on: October 10, 2017, 10:06:47 PM »
The alternator is known as a 12SI and they are easy to work on.  You can easily find parts by doing an internet search.  My experience has been the diode trio fails or the brushes wear down to the point where they no longer make contact.  The brushes, diode and voltage regulator can be found in a kit that costs about $10.  My alternator is still running on the original bearings.  It has 117,000 miles on it.  The bridge rectifier is very robust and heavy duty so I would not expect it to fail.

Here is a link that shows how to rebuild them.

https://www.youtube.com/watch?v=NWMANjkgtFw

Warren

Thanks Warren.  That's really what I was looking for about it being the 12si. I've been looking up info about replacing the diodes and everything and it just seems too easy to do and I don't like paying someone else to do things I'm capable of doing myself. I appreciate the info.

Josh78T/A

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Re: Alternator rebuild
« Reply #4 on: October 10, 2017, 10:08:42 PM »
I never do would do a full rebuild because they just don't require it, and why would you bother anyway.  Typically what I have replaced on them was the diodes and voltage regulator.  The parts used to be common at any auto parts store, but these days I think you would have to mail order.

Yeah, I was meaning replacing the diodes and regulator and those things. I should have worded that a little better I guess. I'd been looking up all the info about replacing those parts but really couldn't find about it being the 12si or which one came in the '81s.

Thanks.

Re: Alternator rebuild
« Reply #4 on: October 10, 2017, 10:08:42 PM »

gm muscle

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Re: Alternator rebuild
« Reply #5 on: October 12, 2017, 10:28:51 PM »
I used to buy rebuild kits at Pep Boys for around $8. My stepdad would then do the rest...including the replacement of the bearing. Sometimes the armature was a  bit uneven and had to be turned. Even then, I still didn't pay more than around $20 for everything.
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Re: Alternator rebuild
« Reply #5 on: October 12, 2017, 10:28:51 PM »
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