i have a brand new prop, shaft, bushings, seals, yokes and ujoint on my 20hp go-devil crawsfish longtail. when i hit mid throttle the first jam nut and prop spin up the shaft and lock against the longtail housing. i have both manuals and still cant figure it out. any help would be appreciated. thanks

Yu should have 2 jamb nuts upstream of your prop, set your gap between your end housing and tighten the two nuts against each other as hard as you can. I had a friend and myself to do it and we were on them with 24" Cresent wrenches. When you spin your prop against your nuts and it hits the nuts. Get a mallet or a plastic dead blow hammer and put a screwdriver in the u joint yoke. Hammer on the prop until you've realize it won't go anymore. I then use a jam nut and a lock nut on the "terminating" side of the prop. Repeat the tightening process. USE ANTI-SIEZE BEFORE ANYTHING GOES ON YOUR PROP SHAFT THREADS... some people say to use the low profile jam nuts. I used full sized 3/4 nuts as my jam nuts. I found it easier to tighten them down hard. I believe the box end wrench size for a 3/4 nut is 1 1/8 if I remember right

It's simple. get a mud motor. shoot ducks in the face.

thank you brother, i was thinking it needs 2 jam nuts upstream but the paper work says 1. thats what i get for tryin to follow directions.goin to test it out now. thanks again

No problem. Those top two need to be stupid tight against each other

It's simple. get a mud motor. shoot ducks in the face.