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Squareback alternator

Posted: Thu May 19, 2016 6:17 pm
by coelcanth
my '69 D100 had been upgraded by a previous owner to the squareback (dual field) alternator and the solid state regulator..

lately it seems like it has not been charging so well at speeds under 3000rpm..

how do i test this setup to see if it's the alternator or the regulator ?
(i think the belt is tight enough)

as far as i can see,
there's no 'ground to test' spot labelled on the alternator

Re: Squareback alternator

Posted: Fri May 20, 2016 3:58 am
by wally426ci
My square back runs 11.5 at idle and 13.5-14 at speed

Re: Squareback alternator

Posted: Fri May 20, 2016 3:59 pm
by my5thmopar
Make sure that the regulator is clean and grounded well. 69 so it has the small rectangle mechanical? About 1.5x2.5 or so? If you have to replace it buy a good quality electronic. I bought one online that looks original but, has electronic guts. Craig

Re: Squareback alternator

Posted: Fri May 20, 2016 11:49 pm
by coelcanth
No, the original mechanical regulator is gone,
An old made in USA solid state was added in the past.

Today I bought a new replacement probably chinese from Napa for $20..
To be determined if it does the trick or not

Re: Squareback alternator

Posted: Fri Jun 03, 2016 7:46 pm
by coelcanth
well the new regulator seemed to help for a few days or so..

but then today it stopped charging altogether.

so i took off the alternator to get a closer look, and i could clearly see that one of the rectifier diodes was breaking off it's connection.
it had probably been slowly failing for quite a long time and was now completely detached.

so i rode down to the local alternator shop and they had a replacement negative rectifier and brushes on the shelf,
and i was able to install it right quick,
and now it's working just fine again

$10 fix

Re: Squareback alternator

Posted: Sat Aug 27, 2016 12:12 am
by jdavis
Everything as far as the prevous posts. Now just go to a denso alternator,part # 13220 for 89 Durango with v6,from o'reillys, about 90 amps and you won't have any charge problems at idle. It is a dual field alternator. Just change the spade ends to rings, hook those to the field terminals, then go to Summit Racing and get their 80 amp wire and Maxi Fuse, hook that up to the battery terminal of your starter solonoid and to the large stud on your alt and your charging issues will be minimal. I've done it on my 65 barracuda. I'm doing it next on my 66 powerwagon w/318 poly. Just check out the electrical section(late alternator upgrade) There are pics and explanations.

Re: Squareback alternator

Posted: Tue Aug 30, 2016 4:37 pm
by coelcanth
thanks,
I'm pretty happy so far with the $10 fix
my truck has been running and charging great with the vintage equipment.

I already ordered the alternator internal upgrade kit if i ever need more power or feel the urge to do a quick project.
I like keeping the old original style parts and i also appreciate the simple service procedures for the old parts