66 Fastwin 18 prop or driveshaft freeplay

[Tennessee Cutty]

Brought home 66 fastwin 18 today and put it on the stand. Noticed that with the motor off and in gear I could turn the prop maybe a third of a turn freely back and forth before encountering resistance. It seems excessive but I have no experience with these motors. It starts and runs good but has a suspected spun prop but I'm not talking prop problems I'm talking prop shaft movement.

 

[Joe Reeves]

Re: 66 Fastwin 18 prop or driveshaft freeplay

The shifter dog lobes and the shifter lobes on the gears are 180 degrees apart. The 1/3rd play you feel is the distance between the shifter lobes and is normal. Hold your thumb and forefinger about 2" or 3" apart, now slide them together so that they butt against each other. Now rotate sightly so that one set of fingers slides down the other set.... that is the shift dog/gear lobe setup.

Oh, and that's the propshaft. The driveshaft runs from the lower unit up to the powerhead.

 

[Tennessee Cutty]

Re: 66 Fastwin 18 prop or driveshaft freeplay

Joe thanks for the quick reply. I was looking at some pics in an online parts manual and saw those shifter dogs and got to thinking just what you described. Thanks for the verification. Now a prop question, can the bushing be tight enough to turn the motor over by turning the prop in gear by hand and still be spun to where it wont move the boat hardly?

 

[lindy46]

Re: 66 Fastwin 18 prop or driveshaft freeplay

Very difficult to determine if a prop hub is spun by hand - it can feel perfectly fine. But put it on the water and at speed it can spin freely, causing you to go nowhere. Best way to diagnose is to remove the prop and scribe a mark across the back of the prop and hub. Put the prop back on, take it for a "spin" and check the mark. If it now doesn't line up, you have a spun hub.

 

[Joe Reeves]

Re: 66 Fastwin 18 prop or driveshaft freeplay

Now a prop question, can the bushing be tight enough to turn the motor over by turning the prop in gear by hand and still be spun to where it wont move the boat hardly?

Yes, absolutely. Follow "Lindy's" instructions.