Alternator question

polarus

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To the C body braintrust: What year did Mopar upgrade to the square back type alternator?
 
To the C body braintrust: What year did Mopar upgrade to the square back type alternator?
1972 is generally considered the first year, but I've read of a few 1971 cars having them, but I wouldn't say that's reliable info.

The only advantage with them is the diode bridge is easier to replace, but I've also read (and experienced) more diode failures in them. Again, not reliable info.
 
That question might be answered in the Chrysler MasterTech videos on "What's New" For 19__". Those videos are now at www.mymopar.com and have been on the Imperial Club website for years.

As alternators cool from the back, rather than from the front, cooling the guts of the operation was probably the reason for the change, I suspect. As cars were getting more electrical options, generally, more cooling was probably needed.

Just some thoughts,
CBODY67
 
Well . . . a quick check of the MasterTech videos revealed nothing. I started in 1970 ("Browse by Model Year" as the "Browse by Subject" didn't work) and discovered THREE types of alternators (and their respective voltage regulators!) for 1970, in the voltage regulator diagnosis video. No mention of other alternator-related videos until the 1975 model year 100Amp alternator video. So much for that bright idea!
 
I've got a 71 Newport

DSC07566.JPG
 
Thread -- www.ForABodiesOnly.com June 11, 2015 "Explain Square Back Alternators"

Quite informative and explains the differences between the two styles and types. Plus how to use the newer Chry and Denso alternators on older vehicles.

Extending the items I found in the 1970 MasterTech videos that there are MORE minor differences in Chrysler charging systems, over they years of the 1970s than ever expected.

In this last respect, I recall the late Daniel Stern mentioning that the alternator on his late-1990s Dodge pickup truck was controlled by "the computer". He ended up finding a resistor to plug into the wiring harness so the computer would think it was hooked up to the alternator, then wired the alternator as his old Dodge Dart (later 1960s) with an external voltage regulator AND everybody lived happily ever-after. As the only part of the computer board which had failed was the one section related to alternator charging, so he took that function "external" and things worked well for him. PLUS costing much less than the price of the new computer.

Enjoy!
CBODY67
 
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Great input guys, thanks. When it comes to Mopar nothing is cut & dry. I thought 72 was the first year for the square back but a friend of mine thinks it was 71, (agree to disagree.) I won't even get in to Police package Mopars, Chrysler alternator? Leece/Nevelle? Motorola? All were available in the early 70's squad cars, all required their own brackets.
 
Square back not in the 1971 FSM, but is in the 1973 FSM. Which until I can get into the 1971 and 1972 Chrysler parts books, I am inclined more toward 1972 model year than 1971.

NOW, this is "talking" model years, not calendar years. It IS possible that some late-production 1971 cars could have had the 1972 electrical items, as long as they all went into the same place as the 1971 items. More possible for first-of-the-model year production, typically, during the "transition period" of sorts.

CBODY67
 
Square back not in the 1971 FSM, but is in the 1973 FSM. Which until I can get into the 1971 and 1972 Chrysler parts books, I am inclined more toward 1972 model year than 1971.

NOW, this is "talking" model years, not calendar years. It IS possible that some late-production 1971 cars could have had the 1972 electrical items, as long as they all went into the same place as the 1971 items. More possible for first-of-the-model year production, typically, during the "transition period" of sorts.

CBODY67
It sometimes comes down to running changes during the year. Most of us have had one car or another, particularly newer cars, that you need to know if it was made by a certain date in order to buy parts.

In this case, the alternators are interchangeable in function and fit, so a running change on the line is entirely possible. The square back was just a change in the rear half of the housing too, so it wasn't a complete redesign. IMHO, the square back was probably cheaper to build without the pressed in diodes that needed to be individually soldered, so again, a running change to save money without any functionality change.

Complicating figuring this out is almost all of the surviving cars that no longer have the original alternators and since they interchange operationally, any alternator was obtained and bolted in. The true test would be to dig up a bunch of alternators and look at date codes, although even that might not tell the whole tale as a September build 1972 car might have an alternator that was built in July... and that late build 1971 car could have that July dated alternator too.

When it really comes down to it, I think the safe bet is if you're restoring a 1971 car, go with a round back and a 1972 car will get a square back.
 
I recall the late Daniel Stern mentioning that the alternator on his late-1990s Dodge pickup truck...

Would that have been back on the Mopar Mailing List of the 1990's ? I remember exchanging messages with him at the time, we both had a slant-6 car (my '65 Polara and his Dart I believe). I did meet up with him once on a business trip to southern california in the late 90's (Anaheim unless I'm mistaken). Didn't know he passed.
 
Seems like I first learned of Mr. Stern in the late 1990s (as I was using WebTV back then) from the AllPar forums or the old Usenet Chrysler-oriented BBS? I do not believe it was MML as at that time, MML was more like people conversing back and forth rather than e-mailing. Not what I was expecting, from all I had heard about it back then.

I might have mis-spoke about his passing, but I saw something about that in another forum, possibly an AACA forum, a few days ago. When I went to his website, all looked well and one of the pages was last updated in Sept 2023, so he must still be with us, I suspect.

The Daniel Stern Lighting website has a vast amount of information. Lots of newer content from the last time I looked, about 15 years or so ago. Need to get "caught up".

Take care,
CBODY67
 
Seems like I first learned of Mr. Stern in the late 1990s (as I was using WebTV back then) from the AllPar forums or the old Usenet Chrysler-oriented BBS? I do not believe it was MML as at that time, MML was more like people conversing back and forth rather than e-mailing. Not what I was expecting, from all I had heard about it back then.

I might have mis-spoke about his passing, but I saw something about that in another forum, possibly an AACA forum, a few days ago. When I went to his website, all looked well and one of the pages was last updated in Sept 2023, so he must still be with us, I suspect.

The Daniel Stern Lighting website has a vast amount of information. Lots of newer content from the last time I looked, about 15 years or so ago. Need to get "caught up".

Take care,
CBODY67
Dan posted Friday on FABO and Saturday on the Slant Six forum.

So, I would assume the reports of his death are exaggerated.


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To the C body braintrust: What year did Mopar upgrade to the square back type alternator?

This is an old thread, but I'll add some to it... In sum, the "square back" alternator was introduced as standard on all 1972 models.

From the 1972 Service Highlights:
PXL_20250126_231001674.jpg

PXL_20250126_231023626.jpg

PXL_20250126_231032804.jpg


Some additional, broader, general information from a post I wrote for Moparts:
The Chrysler designed aluminum housing alternator was introduced in 1960 on the Valiant and Lancer models. This alternator had the informally termed "round back" style rear end shield. Chrysler called the two housing, or case, components "end shields". These alternators have one grounded brush and one field connection. This style continued through 1969 with a slight change in the spacing between the fins when comparing earlier Essex built versions and later Chrysler built versions. These alternators were used with an electro-mechanical voltage regulator. This regulator functions by switching +12V DC on and off to the alternator field lead to regulate system voltage.

In 1969, a special alternator was used with the new transistorized regulator in some models. This is the "Insulated Brush" alternator that looks much like the regular alternators of 1969. The difference is the grounded brush of the prior and other 1969 alternators is insulated from the rectifier, or back, end shield. The 1969 only transistor regulator looks like the 1970 and later regulators with the addition of a third terminal lead called the suppression lead, in addition to the ignition and field terminal leads. Other 1969 models not so equipped still used the grounded brush alternator and electro-mechanical voltage regulator.

In 1970 models, the alternator and voltage regulator were again redesigned. The new "Isolated Field" alternator still used the "round back" style end shield although it is slightly different without the grounded brush. Two isolated field connections were now used. This "round back" style was used through 1971. The voltage regulator now contained only two terminal leads, ignition and field. This is why the triangle shaped connector looks like it is missing a lead, because it is. The connector and regulator case are carryovers from the 1969 transistorized regulator with different internal electronics. The regulator functions by switching ground on and off to one alternator isolated field lead with the other field lead connected to +12V DC (Ignition Run). The regulator action is adjusted for temperature too. This regulator was used through the 80s on cars (with a change in 1975 for the different 100 Amp alternator, a slight revision in 1980, and some other slight application variations), and early 90s in trucks.

For the 1972 models, the rear end shield was redesigned in the informally termed "square back" style. The end shield contained a different mounting for the rectifiers and capacitor and connected to the stator without soldering. This simplified assembly and service operations. The electrical functioning of the alternator and voltage regulator remained the same. This particular "square back" style was used through 1977.

For the 1978 models, the end shields and stator were redesigned again. The most visible difference is the "thin" edge of the stator between the two end shields. This is still the "square back" style, but is available in higher capacities than earlier models. This alternator style was used from 1978 through 1987. These alternators can interchange with the earlier versions, but some alignment adjustment might be needed.

Chrysler also used other alternators not included in the foregoing into the 90s such as Leece-Neville in the 60s and early 70s, the Chrysler 1975-1987 100 Amp and 114 Amp, the 90 Amp and 120 Amp Chrysler units introduced in 1988, and Nippondenso.
 
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