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Discussion Starter · #1 ·
Hello all,

I have the starter out, how can I bench test it? There are two connections on it: one is a small black plug, the other is a screwed in type terminal. Should I be able to get the motor spinning by getting +12V to the screwed-in terminal and ground the casing of the whole thing?

How does the whole thing work?
Please correct me if I'm wrong:

The black plug goes to the ignition switch, which when I crank, sends current to the solenoid, moves the spring-loaded plunger (which engages the starter gear), and as the plunger reaches the end of its travel, hits some electrical contacts which now completes the circuit to the starter motor, which then draws electricity from the screwed-in terminal?

Thanks a million!

86 AW NA
 

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Chances are very high if you're having starter problems that the contacts are just worn out. I'd check them first, they're an easy fix !
 

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I've heard its a very bad idea to try to bench test a starter. They produce loads of torque and can randomly kill you O_O!
 

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I don't think you'd have problems bench starting a 4ag starter. If you want to feel safe, secure it somehow. When you bring them to autozone, they simply strap it down. Both connections go to positive and you just want to ground the case. Might want to use higher gauge wire for the screw in terminal since that one is the one that goes directly to the battery.
 

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Secure the starter with something - your foot and the floor will work, if you know what to expect. It will try to get away from you when you first energize it - assuming it's working. Connect the negative terminal of a battery charger (at least 80A.) or battery to the case. Connect the positive terminal to the large connector. With a piece of fairly heavy wire (12 ga or larger) jumper the large terminal to the small terminal. It should immediately start running.
 

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I would like to add that when I had starter issues, benchtesting the starter proved ineffective as it would always work out of the car, but it would only work 35-40% of the time in-car. I replaced the contacts that the others speak of, and it made no difference in the starter's performance. I even replaced the brushes and motor armature with no success. Eventually I gave up on rebuilding the damn thing and bought a new one. After talking with a mechanic at a later date, I found that the bearings in the starter case wear more than you may think. So I went back to my old starter and found that the play in the bearings allowed the drive magnets to pull and hold the armature against them when the motor is energized, preventing the armature from spinning.

For those who may not know, the armature is the shaft inside an electric motor with the electromagnetic wire windings around it. It is the piece of the motor that actually turns.
 
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Discussion Starter · #8 ·
So when the starter is in the car, the wire going into the big terminal is always hot?

(does it not seem weird to have a hot wire with minimal shielding located at such a vulnerable spot in the chassis?)

Thanks for all your replies!
 

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Yup, it's always hot.
 
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