Starter Motor not engaging with Flyweel - 48 Plymouth Special Deluxe

[clarkede]

I recently replaced the starter motor brushes due to a short in one of the wires that caused it to be non-fixable.  The main problem in this repair is that I did not pay attention to the orientation of the brushes to the armature when I disassembled the motor.  So when I finally re-assembled the motor, I assembled it with the brushes in the wrong orientation.  I found this out after putting the starter back in the motor and when I cranked it over, the starter motor spun in the opposite direction and it would not engage with the flywheel.  After researching the problem I thought that the problem might be the brush orientation off by 180 degrees.  I took the motor apart again and re-oriented the brushes at 180 degrees, but when I tested it the motor still spun in the wrong direction.

 

I also suspected that the motor may not be engaging with the teeth on the flywheel due to the spring mechanism not engaging the starters teeth correctly.  This was not the problem.

 

SOLUTION:  I rotated the brushes only 90 degrees with respect to the armature and now the motor spins in the correct direction.  The key difference is that the starter motor that I have has four (4) brushes.  If you are having the same problem I think the 4 brush motors will spin reversed direction every 90 degrees.  Two (2) brush motors may OR may NOT change the rotation of the motor.  Do your research before taking it apart multiple times and frustrating yourself.

 

Edited November 15, 2018 by clarkede

[clarkede]

Oh, I meant to mention that I hooked up the starter with jumper cables directly to the battery.  The starter works smoothly and spins freely.

 

Anyone know how the spring mechanism actually works in the starter to engage it with the flywheel?  I just figure it is thrust outward when the spin of the motor is engaged and then a spring pulls it back in when the current stops flowing. 

[37silverstreak]

If you have the same starter drive that is in my '48 Plymouth it will not disengage from the flywheel just by cutting the power to the starter motor. It will stay engaged until the engine starts and the action of the flywheel overunning the drive at a certain RPM will cause it to snap back into its home position. I recently had my starter out to clean and rebuild it and my drive was in the extended position as well. I just reinstalled it as is and figure it will reset once I get the engine running.