Drive shaft pin
 

I have a 127 hydrostatic. Early this fall I bought a new coupler and a used driveshaft that I made sure a new roll pin fit tightly. I'm positive that I haven't put ten hours on the replacement parts.
Tonight the roll pin just fell out while plowing snow. Luckily I found the pin and managed to drive it back in. I was going to wrap a hose clamp around the coupler to make sure it stayed together but didn't have one to fit. Ran it about ten minutes and it did it again leaving me sit in the middle of the road as I turned around.
I am at a loss as to why this is happening because I had to use a hammer and drift to drive the pin back in. The new coupler is made of steel instead of aluminum like the old one and I am thinking about putting a tack weld on the pin and coupler to keep it all together.
Does anyone have any advise on this recurring problem???

I think your driveshaft is the culprit. Probably worn just enough the pin won't stay in.

I'd try a little Loctite . someday you might have to take it apart again

Use the universal tool, duct tape, BTDT

If you are referring to the pin in the front of the shaft, it is a (solid) steel dowel type pin, a spiral pin will only last a few minutes in there and a roll pin won't last very long either.

If the hole is enlarged I have taken the shaft out and smacked the hole with a hammer on one side and then drove a new pin in from the other side. It's still in there (I guess, it still drives).

If you are talking about the pin in the rear flange on the transmission input shaft, then my best guess would be a heavy duty spiral pin.

I've never seen an aluminum coupler.

I'm listening to Yosemite Sam and I agree. Roll pin, Spiral (Spirol) pin and dowel pin are three different pins. No-no to roll pin.

I grabbed the listing for the driveshafts I make.


The flange end is turned and is part of the driveshaft. The engine end uses a solid pin that should be an interference fit.

The pin is the front one and is solid. I had to use a hammer and a drift to put the pin in the driveshaft when I installed it this past fall.
I used a hose clamp before and will probably go that route again.

Yeah, this setup seems really short lived. I'm thinking of going to a rag joint.

I don't know about the life of a rag joint either. I have had to replace a few of them on some of my Ford cars and that is an easy slow turn and not subject to the high rpm's and sudden jolting that these pins are subjected to.