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Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

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EricD

solonoid

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Kent
The solenoid allows you to run short, heavy cables between the battery >> solenoid >> starter, without having to route that heavy-cable circuit to the starter switch. All the starter switch must do is carry enough current to activate the solenoid, which closes the actual starting circuit. A solenoid in the circuit will deliver more current to the starter motor, improving starting -- especially in cold weather when batteries are naturally weaker... The older tractors ran these long cables to a heavy-duty push-botton starter switch. The ones with a solenoid use only about a 12 or 14 gauge wire and a light-duty key switch... If the solenoid is defective, you can temporarily jump across it to start the tractor, until you can get it replaced....

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Kent
You can see the difference in how they are wired, in these wiring diagrams... http://www.simpletractors.com/service/wiring_diagrams.htm Your 3212H is the same as an Allis HB-212, while the 700/725 is the same as an Allis B-1...

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BLT
Just make sure you get like for like, three terminal to three terminal for instance. And try to stay with same profile. Some relays have their mounting brackets in such a way that , that closing a hood could cause them to short circuit.

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Kent
Bit of trivial pursuit... One of the first mods I used to do to an old 6-volt VW to get it to start in the winter was to wire a 6-volt Ford solenoid into the system, under the back seat. If that didn't solve cold cranking problems, the next step was to buy an 8-volt battery (usually had to order them) and then adjust the voltage regulator to vet over 9 volts out of it to keep that 8-volt battery charged. That gave a big boost to starting, faster windshield wipers and brighter headlights... OH... the good old days when I could drive a VW for less that $5 a month on gas (at about 30 -35 cents a gallon)... only worry was keeping warm in them...

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Roy
Interesting thing about the old VW's with a generator. At night the lights consumed more power than the generator was rated to put out. If you only drove at night the battery would slowly but surely go down.

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