1948 Super A Starter Question

I'm digging into the starter on a tractor I just bought. The previous owner had the battery hooked up backwards, and I assume that's what caused the mess I found in the starter. The armature is ripped apart and useless.

After sixty years of running in one direction, it probably wasn't too happy about going the other way.

Does anybody know where I could find a new armature, or even know the make/model of this starter?

My google efforts aren't turning up anything useful.

Or am I just better off buying a new starter?

Thanks.

The starter would still turn the same direction REGARDLESS OF BATTERY POLARITY....Reversing battery Polarity is NOT what trashed the starter....

However, there can be charging and Genny and Voltage Regulator issues from reversing polarity (though such can be dealt with and she still work fine at either polarity) maybe causing a low state of battery charge and/or starter overheating..

John T

Interesting point - I started thinking about that after I posted the message.

If they DID turn backwards with reverse polarity - then they'd have to be wired "backwards" to begin with to work with a positive ground. Or mounted backwards....

Hmmm.

Either way, my armature looks sort of like a pineapple, and I need a new one.

I'd appreciate any suggestions before I go buy a new starter.

Thanks

If it is grenaded, it likely took out or damaged the field as well. A good used is fine and may be less expensive if you feel OK putting bushings, brushes, and a new style drive in it.
Stuck switches, or contacts will allow them to over rev. Especially if on 12 volts or a booster.
They can stand it for a few seconds, but have been known to explode, even on 6volts. That series wound motor is not self limiting especially when it is not loaded. Jim

It will still turn the same direction at Pos or Neg ground and regardless which lead (Pos or Neg) is attached to the stud and which is to its case frame. You simply cant wire it backwards externally (stud and case frame) to reverse it, you have to go inside and effectively electrically reverse the resultant North/South relationship between the armature and fields.

John T

I have a guy here on the south side of the ATL that rebuilds generators, starters, and alternators. He hasn't backed off on any of the 6 volt stuff I have taken to him including a generator for a 200. You might want to take both the generator and the starter in to a "Starter Rebuild Shop" and they will dig up all the necessary parts. If you do rebuild the generator remember to follow the instructions for "Setting the Polarity" of the generator before you crank the engine.

(quoted from post at 22:43:34 06/16/11) If it is grenaded, it likely took out or damaged the field as well. A good used is fine and may be less expensive if you feel OK putting bushings, brushes, and a new style drive in it.
Stuck switches, or contacts will allow them to over rev. Especially if on 12 volts or a booster.
They can stand it for a few seconds, but have been known to explode, even on 6volts. That series wound motor is not self limiting especially when it is not loaded. Jim

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Actually the Delco starters are self limiting for RPM. There is a specification for RPM when testing along with amperage draw.

I'd have to read through the Delco manual again to get the specifics but basically the current flows through the field coils and then the armature. At low RPM the magnetic fields created by the high amperage draw in both the field coil and the armature cause the armature to spin.

Since the armature is a coil of wire spinning in a magnetic field it starts to generate voltage in the winding. Since the armature is also a magnet spinning inside the field coils they too start to generate voltage This voltage is opposite of the voltage being supplied by the battery. As the RPMs increase this offsetting voltage increases causing amperage draw from the battery to decrease. Eventually they reach equilibrium and as long as the battery voltage stays constant the RPMs will stay at that peak.

The most common reason for the armature to explode is probably a stuck starter drive. This seems to be more common with the newer style drive. That style drive uses a rubber bumper washer to cushion the gear as it comes to the outward end of its travel. Sometimes they go too far and get past the end of the helix grooves. That type of damage usually has wires thrown out from the center of the armature.

If the wires are thrown out from the armature end most likely the starter has been overheated and the solder melted out of the commutator. You will find the solder around the inside of the back of the starter case.

Your starter most likely is a DelcoRemy model number 1107093. The armature number should be 818002. The same armature is used for the H and M and up through the early 12 volt starters. An aftermarket armature will probably cost you about $75 - $100. Having the starter rebuilt will probably be in the $150 -$200 range.

Stop and think if it ran backwards it wouldnt turn the engine over. You didnt say will it turn the engine over and are all connedtions clean is the switch still original you mite just have bad cables just make sure the new ones are 1ga.

Thank you all for your help.

Since the generator was dead and obviously out of commission for some time, I'm thinking it's likely somebody might have tried jumping this tractor from a car at 12v if they had trouble hand cranking it - perhaps they got a little carried away cranking it and blew it up.

I guess I'll never know what happpened, but at least from the info you guys have given me, I can move ahead with some confidence.

as for a shop re-doing the armature, the metal plys are actually sparated and bent. It's total junk.

The bearing and brushes, and somehow even the field coils are apparently all in good condition (after cleaning out the junk)

I'll look for a replacement armature, if I don't find that I'll try to locate a used starter.

(I'd just buy a new one, but my wife's already getting suspicious about all the shopping bags from various tool and auto parts stores...)

Thanks again.

If operated on the design voltage, Yes. If operated at twice or more they will spin faster. They are voltage sensitive, not like a synchronous AC motor, or Stepper. Jim

(quoted from post at 09:50:55 06/17/11) If operated on the design voltage, Yes. If operated at twice or more they will spin faster. They are voltage sensitive, not like a synchronous AC motor, or Stepper. Jim

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They are still self limiting for speed even at 12 volts. I'll have to do some tests to find out just how much faster they run but I normally just check them all at 12 volts after overhauling them.

They are self limiting in that they go as fast as they can, and no faster, based on the amount of voltage. They can go too fast for their own good. Other motors Which are phase locked, cannot go faster than the pulse/wave frequency. A boost charger can put out ~18 to 20 volts, enough to make hay out of the innards if it "freewheels". Been their. Respectfully, Jim

I just got a quote from my local Alternater & starter shop for my A. $125.00 with a 24-48 hr turn around. Much cheaper than the $300 or so for a new one and it is warrented. NO MAIL order stuff to deal with either, i.e. shipping charges. Plus you are encouraging you local econonmy as well.