72 Electric Shift Lower Shaft turns both ways

wireready

Seaman Apprentice
Joined
May 26, 2009
Messages
46
I'm planning on swapping my lower unit on my 1972 johnson 100HP V4 electric shift. I obtained a spare lower unit on ebay. I pressure tested it, and the solenoids ohm out okay, oil looked clear, no metal in it. However... before I swap lower units and put the boat back in the water, I wanted to know if there is a quick hand turn test to make sure the gears are okay.

with the gear oil drained- is it normal for me to be able to turn the drive shaft in either direction and see the prop turn, and likewise if I turn the prop shaft it too can turn in either direction and the drive shaft will turn? If I turn the one shaft cw, the other turns cw, if I turn one shaft ccw the other turns ccw. Sometimes if I turn the prop shaft by hand clockwise, it will skip ever revolution or so - like a cog is popping over. My recollection could be bad, but the last time I hand tested a prop shaft, I could turn it in one direction but not the other. Granted that lower unit was full of gear oil and the water pump/impeller was installed. This lower unit has no oil in it, and the impeller/housing happens to be off.

If anyone can suggest to me what kind of movement should be normal if I turn the drive shaft or the prop shaft in either direction that would be great. Also let me know if I need to fill it with gear oil to do the hand turn test you are suggesting.

I just dont' want to go to the trouble of swapping my lower units if this was is no good.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: 72 Electric Shift Lower Shaft turns both ways

The default shift mode due to having a spring loaded clutch dog is for the lower unit to be in forward gear. That is..... the shifter dog is actually shoved into the forward gear, a safety feature so that one could get home if the electric shift system failed.

With the dog engaged into forward gear, the propshaft will obviously turn (one way or the other) when the driveshaft is turned, regardless of whether it is turned clockwise or counter clockwise.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: 72 Electric Shift Lower Shaft turns both ways

The popping over as you describe it is normal too. That is, if you are turning it in the normal direction and holding the drive shaft from turning.
 
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