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Topic ClosedMotorola alternator information

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billd View Drop Down
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Direct Link To This Post Topic: Motorola alternator information
    Posted: Aug/22/2013 at 1:04pm
IDENTIFYING Alternators used by AMC
This round - Motorola -

In the years prior to spring 1970 the alternators manufactured by Motorola were numbered according to this plan (with some variation in stock off the shelf replacements, etc.)
The first character or characters was the series. With AMC this was always an A which meant standard automotive and industrial type, 5" frame.
The next number(s) are indicative of the voltage - in the case of AMC, this would be 12.
The letter immediately following the number(s) indicates positive or negative ground system. For AMC cars, this is negative ground, so N.
Prior to 1970, Motorola used 2 letters to indicate customer, for American Motors, this was AM.
So far on a typical Motorola supplied alternator, we have A12NAM for A series, 12 volt, negative ground, American Motors.
This is where things get sticky - normally in a standard Motorola model numbering scheme, after the prior-mentioned numbers or letters,  is the amperage - such as 35 or 55 or 40 or 60.  HOWEVER, in the case of units manufactured for specific customers, the scheme was changed and the last characters indicate model specifics such as clocking of the rear frame, pulley size, and regulator the customer wanted paired with the alternator.
This is why for a given model year you may see that there are 2 or even 3 possible Motorola model numbers for that year, yet all 3, or if there are two, both may be either 35 or 55 amp for example.
AMC would use one sub-model on a 6 cyl, perhaps another on a 70 or 30 series V8, maybe a 3rd on a big body car. In some cases the reasons are obvious - different pulley sizes dependent on the car, engine power, and needs, or clocked differently to make connections more logical or easier to assemble, etc.

I am attempting to gather enough information to eventually fully decode ALL charging system variations used on AMC vehicles over the years - just exactly what does the A12NAM453 vs. the 455 indicate, or the A12NAM604 vs. the 605 (6 cyl vs V8)

This variation in models used over the years based on engine and vehicle and so on also makes it pretty tough at this time to be 100% correct in restoration.  Although excellent reproduction tags are available for the very common V8 models in popular model years (where there is demand to make it worth doing), not all are being reproduced. For example, those with a 6 may have to decide between going with a V8 model number tag on the alternator or re-use the original if salvagable. (I keep tossing about totally crazy ideas to get around that, but don't have the monetary resources to do so. Wishful thinking.......)

Physically identifying a Motorla alternator as from or for AMC originally equipped with Motorola isn't too bad a task. One only needs to keep in mind that they were all the A series, they all had the same mounting foot and adjustment ear on the front frame.
If you see a Motorola with a front frame that has THREE holes for an adjustment bolt, or, the rear frame has a boss on the rear bearing area that protrudes an eighth of an inch or so and a threaded hole on each side of the brush cover, it is either a remanufactured unit, a universal replacement unit, or someone found a "Motorola alternator, it must be AMC" somewhere and bolted it on. AMC did not use any units with the rear regulator mounting boss, nor the 3 hole adjustment ear. They all had aluminum model tags held on with rivets (up to the middle of the early 70s) or tiny screws (later middle 70s to mid-70s). Tag colors may be teal, black or yellow depending on year and model (and engine in some cases) The tags will always be attached to the side of the rear frame, (in other words, on the side of the alternator) and the print readable with the alternator pulley facing away from you.Up to the mid-60s the pulley was cast and solid in front, after the mid-60s they switched to a stamped steel pulley and the fan spacer size was reduced in thickness. 2 pulley sizes were used on AMC cars.
The isolation diode heat sink (or mounting plate, usually just called "isolation diode) will always be RED - red indicates 12 volt negative ground. If it is not red, it's not original (and may even be incorrect!)
The pulley and fan were never painted on new units, however, genuine AMC remanufactured alternators had painted pulley and fan as well as 2 yellow inspection marks - one on the front frame, another on the rear frame.
Alternators as installed by AMC at the factory (their bulk purchases) had a silver-gray plating on them.
Replacement pulleys and fans (such as dealer replacement parts in the AMC boxes and sold by AMC)were a yellow zinc color.
AMC replacement alternators, "NOS" dealer stock bought from AMC also had the silver-gray plated pulley and fan.
Replacement Motorola alternators not from AMC had a yellow plated pulley and fan. This yellow typically faded away fairly quickly once off the shelf and out of the box.
So if your car has a Motorola alternator and it appears to be a more yellow plating on the pulley and fan, it may be a replacement pulley and fan (if the yellow lasted that long), or check the model tag, it may be a Motorola replacement alternator.

In the near future I hope to include in these posts images and descriptions of the basic wiring diagrams to help troubleshoot, or in some cases if the owner has a strong desire to do so, "convert" to another system..
I will also be adding troubleshooting tips and procedures to make it easier for the typical AMC owner (is there such an animal??, probably on the endangered list.) to troubleshoot their own charging system with just basic tools, without fancy equipment.
I prefer they be armed with the *correct information* and tools (knowledge) instead of legend and myth. 
My goal is also to help others to keep their AMC as much AMC as they wish, take some of the mystery out so they can have fun and enjoy the car.
(What I get in return is priceless.)
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Direct Link To This Post Posted: Nov/12/2017 at 9:50pm
adding Motorola model/application information - have much more but will quickly post what I have in memory - 

Motorola Automotive Products (MAPI) Service Bulletin 31 dated April, 1969 states that commencing with their 1969 model year they will no longer be numbering products with the old system that identified the OEM they sold to but would be moving to a standardized model numbering system that would no longer identify the OEM. This would lead to lower costs, lower warranty costs due to needing to stock numbers specific to a particular OEM and so on.......... and could lead to several OEMs using the same standard model number alternators instead of each having their own. 
What this means, in a nutshell, starting with the Motorola production year 1969, Motorola would no longer number alternators, regulators, etc. with the OEM code embedded in the model number. 
Prior to 1969, Motorola sold alternators to AMC with the AM designation, such as A12NAMxxx where A was the series, 12 was the voltage, N was negative ground and AM was AMC.
AMC would be buying Motorola alternators starting with 1969 with the new Motorola standard, such as 8AL2 and then the three digit model number and the letter code indicating output amperage, F for 35 and K for 55, etc. 
What this means - any 1970 model AMC that had an alternator with A12NAM in the model was being shipped with left-over inventory from the prior model year. New stock from Motorola would have the new 8AL2xxxy model number. 

Alternator to car - 
1968/69 Javelin and AMX V8 without AC
Motorola model A12NAM455   35 amp, clocked at 9:00  with 2 7/8" OD pulley

1970 Rebel and Rebel/Machine with V8 and non-AC:
Motorola model 8AL2007F    35 amp, clocked at 9:00  with 2 5/8" OD pulley

Edited by billd - Feb/28/2018 at 10:55pm
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