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Discussion Starter #1
I have run into something that I suspect might be common based on the way the hydro input shaft is made on the '77 300's.

In less that 50 hours of operation I have sheared 2 spring pins (1/4" x 1 1/2" acquired from Fastenal) that secure the drive shaft yoke to the input shaft on the hydro. On this vintage the shaft is just a plain round non-keyed shaft that takes the spring pin to make the connection. There would be a fair load on that pin and even with the fiber disks that act as the u-joint I suspect that there is some amount of additional torque and strain placed on that pin. It takes all the forces of turning the input shaft without aid of a key way or splines.

Has anyone else found this to be common on this vintage setup, or do I have something else going on here that I need to be looking at. It is not a tough thing to fix when it happens, but removing the fender pan each time is getting old. If this is going to be a common thing I might mod that fender pan and create an access hatch over that section.
 

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UT, I don't know this as a fact, but I've read that JD uses a harder roll pin than is normally available. There's no harness or material spec on the JD parts spec, nor on any commercially purchased roll pins! I'd go with a roll pin from JD and see how long it lasts. Bob
 
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Discussion Starter #3
I have ordered some Deere official roll pins and will see if that is a possibility. I guess time will tell.
 

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It appears that some s/n machines used a spring pin, while others used a true roll pin (spiral) type. You could try JD # M81896 which would be stronger than a standard spring (single wall) pin. Fastenal probably has them too. If the holes in the hub or shaft are wallered out, that makes them shear much easier. I think you can still use the safety wire through the pin, but may need a smaller diameter wire.

tommyhawk
 
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