Alternator repair, a little show and tell.

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Mattax

Just the facts, ma'am
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I finally got around to fixing a squareback alternator I removed from the Barracuda a year and half ago. It came out because its output was weak. Thought I'd share some of the repairs here. Its not meant to be a complete 'how to.'

First thing was to remove the pulley. This had nothing to do with the needed repairs. It was about me not liking that pulley. It didn't have great alignment, I didn't need a double V, and so its just extra weight. Yes - I care about weight. Every pound adds up. :realcrazy:

upload_2019-3-17_22-38-13.png


Removing pulleys is generally easy if you have a puller.
Unfortunately for me, this pulley had a non-standard nose and none of the pullers I had, or could borrow, fit.
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My solution was to grind and file the pulley down until the puller slipped on. Still was a ***** to remove. Too much interference fit. It was maybe scrap before, now I'm never use it again!

Started going through the bench tests in the shop manual. Rotor was good.
upload_2019-3-17_22-52-20.png


Vertical brush was pretty worn. A little surprising for the miles.
upload_2019-3-17_22-55-33.png


Here's what it looks like inside the back end.
Notice what looks like black grease around the bearing and splattered throughout.
upload_2019-3-17_23-7-5.png

On the squarebacks, the stator windings are bolted to rectifiers. This makes all of the components easy to test and replace if needed.
To my surprise, both rectifiers were good.
Remove the three nuts and take out the stator.
Checking for continuity in the stator windings and found one was open. So that explains why output was low.

On the front half, the copper slip rings were a little dirty to say the least. I think this is because something is missing. The book shows a grease shield should be in front of the slip rings.
upload_2019-3-17_23-15-19.png


This roundback had the plastic grease shield. Removes pretty easily if you are careful.
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to be continued
 
Pulley Alignment.
Pulleys get pressed on until the inside tip contacts the drive end bearing. As shown in the photo, the 2 V removed from the squareback was causing the belt alignment to be a bit off. The solid pulley on the far left weighed in at 1 lb. A factory pulley 7.5 oz, and the solid two groove pulley at 1 lb 7.5 oz after it underwent some weight reduction surgery.
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Idealy you're supposed to press the pulley on with a pressure gage so you know when the pulley is contacting the bearing. Well I don't have one. An arbor press would have been nice, but I don't have one of the them either. So I measured the depth with the tail of vernier caliper and then marked the pulley. Then pressed it on.
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The pulley has to be installed while the back half of the alternator housing is off.

Installing a new stator took a bit of trial fitting. I didn't want the winding or attachment wires to rub the outer housing or touch the through bolts.
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After installing the new stator, decided to take a quick look at the old one to see if it could be fixed.
Removing the insulating tape or shink tubing from the Y connecting joint revealed the break.
upload_2019-3-18_0-15-53.png
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Looks like there's enough wire to cut, clean and rejoin....when I have time at the garage...

After reassembling the halves, all looked good,
upload_2019-3-18_0-21-29.png


But the rotor didn't want to turn freely :eek:

Its good to have extra alternators to compare with.
Notice something different about the rear bearings? Two things actually.
upload_2019-3-17_19-39-37-png.png

The center of the squareback's bearing is blue from heat, and its flush with the casting. H'mmm. So the rotor shaft must have been lightly bottomed out in the bearing.
Looking at the roundbacks, its seems the bearing wasn't pressed to the right depth. Then when I put the grease retainer on, it must have contacted the inside of the bearing housing.
upload_2019-3-18_0-30-28.png

The fix was pretty easy. Took the alternator halves apart. On the squareback there's room for a 15/16" socket to sit and support the casting while pressing the bearing another 1/16" further. :)
 
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Been a LOOOONG time. Make sure the rotor and stator are compatible, something that is difficult to do with rebuilts that may have been "mixed" parts

How did you test the rectifiers? You can NOT check them with an ohmeter/ multimeter. You MUST provide a substantial load for these. I'd guess about 10A or so. I used to have a small carbon pile used for testing generators. Same idea as a battery load tester, except easier to adjust. If not that, at least use a couple of stop/ tail lights jigged up in parallel to provide a few amps load

Examine the case halves carefully where the stator sits in the landing. These guys tend to "work" in there and then the the stator does not sit square. "Back in the day" I blew a few of these up from that---RPM and vibration. Then the stator rubs the rotor (you can see the marks) and this vibrates the windings until the stator insulation wears off as the windings wiggle around. With the engine running in the dark, you can see a "mini lightning storm" as the windings short against each other

Brushes may have become a problem. Last time I needed a set of brushes, from NAPA no less, they were just plain wrong. As I recall we ended up with 3 or 4 boxes, at least one, maybe two had different pieces than the other two. I basically pulled the parts I needed from two or three brush sets and sent the others back as defective/ packaged wrong.

Somewhere, some poor sap has the "really wrong" brush parts that were left over
 
How did you test the rectifiers? You can NOT check them with an ohmeter/ multimeter. You MUST provide a substantial load for these. I'd guess about 10A or so. I used to have a small carbon pile used for testing generators. Same idea as a battery load tester, except easier to adjust. If not that, at least use a couple of stop/ tail lights jigged up in parallel to provide a few amps load
I did use the ohmeter setting but didn't trust it. The lamps are a good idea for a load test.
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I bought this off e-bay cheap, but was in pretty bad shape. Got it to work but movement isn't smooth. I *think* good enough for a go / no go.
upload_2019-3-18_9-23-3.png


Examine the case halves carefully where the stator sits in the landing. These guys tend to "work" in there and then the the stator does not sit square. "Back in the day" I blew a few of these up from that---RPM and vibration. Then the stator rubs the rotor (you can see the marks) and this vibrates the windings until the stator insulation wears off as the windings wiggle around. With the engine running in the dark, you can see a "mini lightning storm" as the windings short against each other
Makes sense and probably worse with mix and match rebuilds. This stator came from an old stock that seemed to cross reference correctly. The core and loops seem the same as the old one. The leads are obviously different. The one I took out may or may not be Chrysler original. I think not based on the few pictures of NOS stators I've seen on the web.
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I've got two early roundbacks with open windings in the rotors. I don't want an replacement rotor for the reasons you state. Rewind or nothing as far as I'm concerned. Fixing one of them would only be to have a backup on the shelf or if someome was doing a restoration.

Brushes may have become a problem. Last time I needed a set of brushes, from NAPA no less, they were just plain wrong. As I recall we ended up with 3 or 4 boxes, at least one, maybe two had different pieces than the other two. I basically pulled the parts I needed from two or three brush sets and sent the others back as defective/ packaged wrong.
Did OK here so far. The one new brush holder I tried needed some deburring so the brush would slip through freely.
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The way I had this alternator set up was a field modification grounding the horizontal brush's terminal. Notice no plastic washer under the head in the second picture, first post.
upload_2019-3-18_9-59-11.png

Doing something similar now but a little nicer and want to make sure there's no strain on the field wire so it is on the other terminal.
Found a tinned copper ring terminal that fit well and snipped it to make a conductive washer.
Then slightly filed down the raised insulation to be sure the screwhead makes good contact.
upload_2019-3-18_10-4-45.png

I don't know if the early grounded brush will fit. Will try that next, but this will work. Bent the terminal tab down so there's no question about which is the positive and which is the grounded.
upload_2019-3-18_10-7-33.png


Bought most of the parts (not the stator) from these guys.
Chrysler alternator brushesAlternator Parts, Starter Parts, Rebuild Kits, Upgrade Kits
Prices are good and they ship quick. Stuff is mostly Transpo/Wai Wei but I think the brushes are made here.
I had to make up a crib sheet of which brushes and holders go with which alternator...
 
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I finally got around to fixing a squareback alternator I removed from the Barracuda a year and half ago. It came out because its output was weak. Thought I'd share some of the repairs here. Its not meant to be a complete 'how to.'

First thing was to remove the pulley. This had nothing to do with the needed repairs. It was about me not liking that pulley. It didn't have great alignment, I didn't need a double V, and so its just extra weight. Yes - I care about weight. Every pound adds up. :realcrazy:

View attachment 1715305057

Removing pulleys is generally easy if you have a puller.
Unfortunately for me, this pulley had a non-standard nose and none of the pullers I had, or could borrow, fit.
View attachment 1715305082
My solution was to grind and file the pulley down until the puller slipped on. Still was a ***** to remove. Too much interference fit. It was maybe scrap before, now I'm never use it again!

Started going through the bench tests in the shop manual. Rotor was good.
View attachment 1715305066

Vertical brush was pretty worn. A little surprising for the miles.
View attachment 1715305067

Here's what it looks like inside the back end.
Notice what looks like black grease around the bearing and splattered throughout.
View attachment 1715305074
On the squarebacks, the stator windings are bolted to rectifiers. This makes all of the components easy to test and replace if needed.
To my surprise, both rectifiers were good.
Remove the three nuts and take out the stator.
Checking for continuity in the stator windings and found one was open. So that explains why output was low.

On the front half, the copper slip rings were a little dirty to say the least. I think this is because something is missing. The book shows a grease shield should be in front of the slip rings.
View attachment 1715305075

This roundback had the plastic grease shield. Removes pretty easily if you are careful.
View attachment 1715305081

to be continued
Hey Mattax! I myself am getting ready to remove an "ugly" just like yours. I however found another 2 belt pulley with more diameter. Like 1 or 2" more. Can you elaborate about pulley not fitting puller tool? I probably will run in with same issue!:(
 
I rebuilt my Mazda alternator...my rebuild was 2 brushes! $4 at Autozone that had the Nippondenso brushes in stock! My brushes were worn to nothing, one was so low that it wasnt even riding on the slip ring. Spring was just not enough. Great write up.
 
Hey Mattax! I myself am getting ready to remove an "ugly" just like yours. I however found another 2 belt pulley with more diameter. Like 1 or 2" more. Can you elaborate about pulley not fitting puller tool? I probably will run in with same issue!:(

I'll try to take some more photos today. Item 1 in the puller set illustration is supposed to slip onto the nose of the pulley.
upload_2019-3-20_8-28-55.png


On this pulley, the neck wasn't turned small enough.
upload_2019-3-20_8-33-43.png


My solution was to use a grinder and files. I put the alternator in a vise and coveredthe front with cardboard so the grindings and filings wouldn't get in it.
upload_2019-3-20_8-42-0.png


There's another type of puller shown in the service manuals. I actually had access to a partial puller set with that type of puller but couldn't find the right pieces to properly grab the nose.
upload_2019-3-20_8-48-9.png
 
An "outie" pulley puller adapter using old throw away punch clamp rings...…….
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Here's the puller's hub and body as they should fit.
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The alternator went back on the car today, and it pretty much came right off again.
Snugging up the nut on the ring terminals, the output stud moved. :(
So off it came.
Removed the three assembly screws, carefully seperated the halves, and forgot to removed the brushes. :rolleyes:
Not a catastrophe. Just not a good way to do things,
upload_2019-3-20_21-50-52.png

Yellow arrow points to the nut that had to be tightened.

Speaking of removal and installation, I'd be curious what other people do.
My method is to work from the front, getting outer spacer in first, then positioning the inner spacer. From there its a little prying or a little tapping with a hammer depending on what I have on hand and if there's room for leverage.
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Brush ID.
Isolated Field Roundbacks and first series Squarebacks.
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Pre-1970 Roundbacks, One field grounded.
On these, which many call "single field alternators", the vertical brush holder is cast into the housing.
(Service manual calls the housings "end shields")
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The brush and holder numbers are from the retailer linked earlier and made by a company called St Mary's. The new ones I bought came tin coated like the one in the first photo of this post (38-301).
 
Nice post!

Hardest part IMO was the soldering on the new bridge! You need a hot Iron!
 
Nice post!

Hardest part IMO was the soldering on the new bridge! You need a hot Iron!
You're talking about the early ones, right?
I haven't had to attempt that yet. LOL.
Do you have the special tool to press out the diodes?

I've got two 'single field' alternators that died, and an isolated field roundback I got at a junkyard when one of those roundbacks seized up. The junkyard alternator has been a reliable backup. LOL.
To my surprise, all the diodes tested good in the pre-70 roundbacks good but the rotors in both had open windings.
upload_2019-3-20_22-51-7.png
 
You're talking about the early ones, right?
I haven't had to attempt that yet. LOL.
Do you have the special tool to press out the diodes?

I've got two 'single field' alternators that died, and an isolated field roundback I got at a junkyard when one of those roundbacks seized up. The junkyard alternator has been a reliable backup. LOL.
To my surprise, all the diodes tested good in the pre-70 roundbacks good but the rotors in both had open windings.

Yes my 69 is the roundback. I had pressed the diodes before but got or had the whole bridge with all three last time and just needed to solder it all back together.
 
I had a tool at one time that was sorta like a valve spring compressor to install them.
 
I had a tool at one time that was sorta like a valve spring compressor to install them.
I didn't know if there was a work around.
When I asked on moparts, I got an offer to buy one, so I did. :) Looks like someone used it for a C-clamp :eek: so it may need a little tweaking to work well, but it should work.
 
Like I said though, it is nice to see some posts about fixing these rather than buying a reman! It can be done and cool for others to see. With the correct tools it can be fairly simple. Lots of them just need some new brushes and bearings and a good cleaning!
 
I didn't know if there was a work around.
When I asked on moparts, I got an offer to buy one, so I did. :) Looks like someone used it for a C-clamp :eek: so it may need a little tweaking to work well, but it should work.

A modified c-clamp may be a better description!
 
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