why did it come off again if you fixed it? did you not do the new mainshaft?
I've already read up about it there. Tack welding the nut would keep it from backing off. The spline allows too much slack allowing the nut to back off. Tack welding it would lock the nut in place. Course if there's any issues later on, you'll need new shafts.go to quad 4x4's website. Good info on the 5th gear problem. From what I understood the nut coming loose isn't the problem. it's the splines on the mainshaft that cause the nut to come loose. if thats the case welding it wouldn't help.
Did you buzz it with a stick welder or wire welder and called it done?had the same problems and the spline on my gear had gotten so bad that welding just the nut wouldnt have helped so me being tight with my money i welded the gear to the shaft. well that fixed it for about 6 months then it eat the weld right out but it wound up spinning the gear where there was no more splines left. so i had ot do the new mainshaft and gear. i got the shaft gear new nut and bearings with shipping for $360 so i just went ahead and swaped everything.
This wont work, atleast I did another truck, and they had done this... it just rocked itself right through the worn area eventually, dont know how long it took, but it came off again!when you put it back together take a punch and mess up one area's threads behind the lock nut, then if you need to work on it again you just drill out that area and unscrew the nut