recently my longtail has decided it wants to spit the key out of the yolk/shaft. This occurs atspeeds as low as idle and even when the set screw is cranked down. Just jb welded it so hopefully it will stay in but what could cause this?

vibration would be my guess as well...
It is a brand new shaft and motor mounts are tight(will double check in morning)

Sounds like you need a new set screw with a point to bite down into the shaft. Then tie the set screw in place with wire through a hole in the head and around the shaft. This will keep the set screw from backing out.

^x2. I had the same problem with my long tail. Drill miner hole for set screw to get down a little farther

X3 on that.... Had the same problem with my GDLT and did the same thing.

I wouldn't mess with drilling a whole above the keyway. Most likely you will break your drill bit and your tap when you hit the square key channel. Instead tack weld your keyway to your u-joint itself, that was you can still get your ujoint off the shafts and all you need to get your key untacked is a hack saw blade. This will keep your square key from working out of your joint. Good luck

I concur with the previous posts about repairs. I was on a camping trip with my family some years ago on the river. My key fell out and of course I did not bring much with me. I managed to jam some sardine can "keys" into the keyway and it held enough so the 18 HP GD LT got us back the many miles back to the landing.

Ill have to get someone with a welder to put a tack on it. In the meantime I drilled a very small hole iny end then ran a strand of wire through it and wrapped it back aroun the yolk. This seems to be holding on the last two hunting trips but still agree that a tack is the correct long term solution.

I just welded my shit. I dont phuck around though

I need your outlook, I should have learned that lesson by now...