My prop shaft sheared off on my 35hp gtr tail without warning yesterday. I was running in deep water didn't hit anything. Motor was ar roughly 4100 rpms heard a pop and the rpms spiked and smoke came out of the carburetor. Any ideas on what caused this what else it may have damaged and what it might cost to fix it?

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it was just time for it to turn loose. somebody hit something hard with it, or there was a flaw in the shaft. they always seem to breakoff when your in clean water. lol

just call gatortail and get a new shaft and a prop. these things happen when u use a mudmotor like a mudmotor. no biggie. I have no idea of the cost. 250 or more for a prop and then u need a new shaft, nut, and i'd replace whatever seals there is in there.

was there a vibration you been feeling but couldn't find? I had one do that and it was driving me crazy till the prop flew out of the water and across the bayou. lol couldn't find it either!!!

Got a guy in raceland Louisiana who does shafts if you need a new one, he does all the boats down here, depending on where you are located out of bro

Quick question, Gator tail says grease lower unit every 15 to 20 hours. Was this done?

Looks like you had a small stress crack that migrated over time. On the left half of the shaft, that "ridge" appears to be a stress crack. Pic is hard to tell, but it could have been that way for a Long time. The constant natural vibration of the motor will eventually make it spread.

The lower unit had just been greased 4 hrs before it happened. I bought the boat second hand off louisiana sportsman it was my first GT and I havent drove a different one to know if the vibrations I felt were excessive. It wasnt the easiest thing to drive always wanted to pull one way or another. They fella I bought it from put a stage 2 kit on it and a bigger prob but never changed the shaft. Im thinking that the added torque may have been the cause here. Luckily I still have the stock prop it came with so there's one thing I wont have to buy.

It's not the added torque. There are motors running with a lot more torque/hp than that one that don't just snap the prop shaft.

Someone might have, but I have never heard of anyone "upgrading" the prop shaft due to mods. Not even sure what you could upgrade to.

Not that uncommon.

Most likely hit something and did the damage. Lasted a while and eventually gave out. Hit could have been an hour before or a year before-no way to know for sure.

Also, I think every one I have heard of snapping was in deep water.

Someone a while back had a theory on why that is, but I don't remember what it was.

Fix it, move on.

It's a mud motor. Things break if you use them as intended.