72 amps from my 55 amp marchal

[bigchillcar]

pulled the alternator after determining it wasn't putting out as it should. richard, my alternator guy, said the diodes were burned out along with the rotor and stator..a big roaring mess. anyway, he replaced everything, brushes included so that it's basically a totally new unit, good 'ol usa parts built. sticking it on his machine, it's putting out 72 amps! yippee! no more radio cutting out on me when the volume is high, at night, with headlights on, etc.....$148 for everything.

only thing..he lost my woodruff key and i had to find one at a hardware store..i think i bought a '6'..something like 5/32 by 5/8's?? maybe? anyway, does anyone know what size it should be? should it have been a metric size? this one seems a little small, as it wasn't difficult to put the fan on or take off..
ryan

[rs dreamer]

The software I have shows a WOODRUFF KEY 4 X 6,5 for a 1973 and is in mm. The part number is 900 118 006 00, and Stoddard had a superceded part not long ago. Gary

[bigchillcar]

thanks, gary..i had a feeling there had to be metric keys. i'll look it up.
ryan

[HawgRyder]

How did the repair guy get more amps out of the same windings?
Just installing bigger diodes should not give more power.
The size of the wire is the limiting factor in the altenator.
Bob

[bigchillcar]

bob,
you're right..he had to replace the windings as well.
ryan

[bigchillcar]

also, richard explained that most alternators are 'underrated' by maybe 5-10 amps, so that a new 55 was probably 60-65 amps if bench tested when new.
ryan

[HawgRyder]

OK...question answered.
Now....where did he get those new windings?
Are they available over the counter or only as a "garage replacement"?
I would like to modify mine and replace the bearing at the same time.
I have no real loads on the system, but having a better alt would be good insurance.
Bob

[bigchillcar]

bob,
richard does only starters and alternators..a small shop. i know he sources parts he needs from suppliers in atlanta and dallas among others. i think he used new 'otc' windings, but he stresses that he doesn't use 'cheap foreign parts' like are commonly used on new alternators. if you'd really like to know, i can call him or give you his number to answer any questions about what he did: richard at 501-821-3940 in Little Rock. He just did the work, so it will be good to call soon while still in his recent memory.
ryan

[Lorenfb]

"also, richard explained that most alternators are 'underrated' by maybe 5-10 amps, so that a new 55 was probably 60-65 amps if bench tested when new."

Not true! That alternator is even marginal at 55 amps. There's NO way of
getting more amps without a larger stator (which won't fit) & higher capacity
plates diodes. The alt. tester used needs to be calibrated & is probably off
by 20 amps TOO high. The other factor is the voltage measured at the load
current, e.g. probably 50-55 amps @ 14V, 12V @ 60 amps, 8V @ 65 amps.

The key for any alternator is not only the peak amps but the
sustained amps under continuous load AND high engine temps.

Bottom line: Your rebuilt is basically the same as the OEM original
which probably developed a lower output over time because of;
worn brushes/slip rings, weak diodes, bad diode wiring. & etc.

[bigchillcar]

loren,
i don't believe richard would lie for simply no good reason. he mentioned to me on the phone that when he tested it the output peaked at 72 amps, obviously there was no load or high temps on the bench. when a manufacturer claims the marchal to be 55 amps, what are they saying exactly then? not peak amps on a benchtop? i'm in no position to argue absolutes on any of this, only know what he reported to me, but i know that i can run my fan blower, headlights and be at high volume on the stereo now while idling..i've NEVER been able to do that before, even years ago with this same alternator. there has nonetheless been a dramatic improvement.
ryan

[RoninLB]

Auto alternators are not built to operate continuously ay max amps. Even though my two Valeo 75amp alt maxed out at 90amps each on the bench I suspect that they would overheat very soon at that output.

A KK or KKK rated alt is built heavy duty.. don't remember which is correct.

[unclebilly]

It would be great if someone in the know could pipe up with the part numbers for the off the shelf american parts to rebuild the marchal... I know it would help me out.

[bigchillcar]

unc,
look up in this thread..i posted richard's phone number. give him a call, tell him ryan with the marchal alternator sent you. i'm sure he'd give you the info over the phone.
ryan