drive pin or no drive pin

[chilly1]

My 1971 55 hp 557 hc Chrysler manual calls for a drive pin and it or a homemade spacer is necessary to take the play out of the prop on the shaft. I read here somewhere to not use a pin, but is this advice good on my set-up?

If not, what makes a good spacer?

Thanks,
Joe

 

[steelespike]

Re: drive pin or no drive pin

Your motor appears to be a 72. My aftermarket manual says prop uses a pin and has a cushion hub.No indication of running without a pin or a spacer.
My drawings the shaft looks smooth if there was no pin how would you drive the prop?

 

[chilly1]

Re: drive pin or no drive pin

Thank you for your fast reply! The rain is all that kept me off the water today. Hope to go after work tomorrow. Warning. rookie here. Have been working over this 'free boat' for a year and change, and it is all new to me.

I have a (14?) tooth splined shaft, and a worn o ring in the prop cone. The slop, however, is at the leg end of the drive pin hole, not the cone end. We are only talking about 1/16" here, but I do not know what is ok, and what is not. A shop made drive pin (bolt stock) takes out all slop, but will not shear if I hit something, but the inner hub probably will. What do people do? This motor is too old to replace anything needlessly$$!

 

[Frank Acampora]

Re: drive pin or no drive pin

Hitting anything will never shear the pin. It only locates the prop fore and aft and takes the thrust load. The shaft splines take all the load necessary to spin the prop through the water. The hub is rubber cushioned and will slip if you hit something hard enough.

Since there is no room behind the prop for a shaft collar, the only option you have is to play with different sized Orings inside the prop tail cone.

Under load, you will not notice the play on the prop shaft; the thrust loads through the water will keep it (usually) loaded to one spot.

The only time I ever noticed it was with my bronze racing two blade prop. Three bladed props never caused me a problem.

Incidentally, I never did like that drive/thrust pin taking all forward thrust and did check to see if I could install a collar behind the prop---no-go. But on the other hand, with years of use on my 1967 engine, I have NEVER worn or broken a drive/thrust pin so I guess it is reliable.