rebuilding an alt

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Rapid Robert

Rapid Robert

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70's squareback. can I rebuild this at home & if so what areas do I attack? I have one that O'reillys says is only putting out a few volts iirc. O'reillys has a pulley puller if needed. thank you for your time. RR
 
How to videos on YouTube, you can follow along.

Spin it over by hand to feel if the bearings are rough for starters. Brushes can be replaced and the contact rings they ride up against can be cleaned up for better contact.

Good Luck


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If it is not brushes or the diode block, the rest of a rebuild is probably more trouble than it is worth.
 
Diodes do not 'wear' out. Unless somebody reversed the bat leads they should be ok. Easy to check.
 
Many parts for rebuilding are not available. It is best to buy an alternator already rebuilt that has all the good parts in it and is guaranteed.
 
I pulled one apart and polished up the casing and changed the bearings in my teens. Always made noise after. Sitting in a box somewhere. I'm not the sharpest tool in the shed sometimes and probably did something wrong.
 
Bewy said:
Diodes do not 'wear' out. Unless somebody reversed the bat leads they should be ok. Easy to check.
Click to expand...
Not really true. Diodes, like most electronic components are degraded by heat, corrosion, thermal cycling, mechanical stress and applied voltage. They are very reliable compared to moving parts, but still can “wear out” after years of use.
 
Easy to rebuild. New bearings, lightly polish the copper on the rotor, new brushes and holders, diodes are replaceable in banks. Need special puller for the pulley and a press for the bearings.
 
If bearings diodes and brushes are your only concern, they are available. The rest are not.
 
This job is too easy not tackle.
Almost without exception, the brushes get to be too short, and the alternator slowly quits. Or, the bearings get to be noisy. Yeah, I bought a puller for that, and eventually, a press lol. after that I rebuilt a pile of them, for spares, most of which have been put into service. My shed now has a pile of cores again.
Getting the pully off is the hardest part. I bought the tool IDK maybe 40Plus years ago and haven't bought an alternator since. But I keep spare brushes in the glovebox.
 
Rapid Robert said:
70's squareback. can I rebuild this at home & if so what areas do I attack? I have one that O'reillys says is only putting out a few volts iirc. O'reillys has a pulley puller if needed. thank you for your time. RR
Click to expand...
Yes.
Depending on what you have at home, and what isn't working.
Only putting out a few volts? I have no idea what the ___ that means. They probably don't either.

The the tests are in the shop manual and pretty easy to do. Actually really easy to do.
You'll need a multimeter to read ohms, volts, and preferable a second one but otherwise just one that can read up to 10 amps.

Now if a bearing is shot, or anything in the pulley side needs the pulley off, then you'll need a puller and a press. Put if its just electrical then its just basic tools you already have.
 
Before opening it up start with the basic checks for the field circuit being grounded or open, and the output terminal (stud) isn't grounded. Then do field current draw test on the bench.

Ignore the mess. Grounded field alternator.
On your isolated field alternator its almost the same hook up.
1718823124814.png

1. Connect the field terminal to the battery negative (unlike the photo yours is not and should not be grounded).
2. Set the multimeter for 10 or 15 Amps. For this meter pictured it means plugging one of the leads into the 15 amp position and turning the dial. Connect the one lead from the meter to the second field terminal.
3. Connect the other lead of the the multimeter to the battery's positive.

Try to turn the pulley while the reading the current. (you should feelk some resistance) Disconnect. Done.
Compare the field current measured to the spec for the alternator.
If you didn't have a second meter reading the voltage while testing, best you can do is check the battery voltage after. As long as its over 12 volts its close enough.


The holders and brushes for all but the revised squareback alternators shown here:
Alternator repair, a little show and tell.

Two on-line companies I've used for new parts:

chrysler alternator parts

Premium quality alternators, alternator parts & alternator repair kits forearly chrysler alternators at wholesale.
www.aspwholesale.com www.aspwholesale.com

Quick Start: Alternator Exploded Views & National Quick Start Sales, High output alternator, Alternator & Starter Parts


Alternator repair, a little show and tell.
 
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There are minor internal differences over the years. The details I don't recall off the top of my head but you may find thin mica insulator or a three piece item later replaced with a two piece item. Its kindof obvious when you have it apart.
 
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