Just finished my homemade longtail and love it. The only problem is I can't seem to get the set screw tight enough on the key that I have on the driveshaft. The driveshaft keeps working its way down out of the U joint. I've tightened the hell out of it. I mean to the point where I bent the allen wrech. And I've also used a healthy amount of the red high strength thread lock and allowed it to sit overnight. But after an hour of run time the shaft works its way out again. Any ideas?

i talked to a guy that said he puts just a tiny weld to hold it in and can be ground off quick

a small weld tack i have done before worked okay, do you have two set screws? one on shaft and one on top of key way?

anotheir thing i was told was take a drill bit and drill a divet in the key so the set screw slides in further

Rendon I only have one set screw and its on top of the keyway. I guess I have to drill and tap the other side of the yoke and add another set screw on the opposite side of the current one.

The set screw should not be set in the key. U can drill a 1/4" hole in the shaft to screw in the set screw. The hole should be a tad larger diameter than the screw.

Hmmmm dont think you should drill into the shaft. It will weaken the shaft

I used to have that problem with my old godevil. I just welded the thing, but I Wouldent recommend it. A small tack Wouldent last notice. First hit it took would break it. The screw idea would weaken the shaft.

What kind of bearings did you use? Is your whole shaft moving or is your key way on top just coming lose? On my homemade LT I have a total of four set screws along the shaft.

1 on key way on u joint
1 on shaft opposite of key way in the u joint
1 on upper bearing at top of shaft housing
1 below lower bearing

Have had no problems at all

On my lower set screw I drill the shaft just a tid bit

^^^ you said drill a hole, not a divot. big difference.

divot is fine, a hole all the way through is not. your meaning wasn't clear.

I have two set screws, one on the key and one 90 deg from the key. Get 7/8" or 1" long set screws. Also get a drill driver bit that is the right hex size. (3/16 on mine) Put that bit in a 1/4" socket. Red loc tite and tighted the fire out of them then jam nut with loc tite on the outside. Worked for me 10X.

Pat

i notched my engine shaft so that the set screw would have a flat place to bottom out, and also something to push against so that the u joint didn't keep pushing farther up on the engine shaft. Tightened the heck out of it and used a bit of blue thread locker. Didn't have another problem out of it all season.