One more TTT to see if I can find out anything more from anyone else...

 

i have a 2000 scrambler 400 4x4 and i tryed it but it doesnt do that to me i think that it might be electrical or its just something on the 500 and sportsmans

 

I almost wrecked cause my scram was jumping in on on side briefly. No, Its not electrical, most likely anyway. , you've caused it over time and did not even know it. I'm sure like me, you enjoy the thrill of coming out of a mud hole in AWD and hammering down a trail and then launching off that jump at the end of a trail. All the time we leave our atv's(don't matter which model) in AWD cause they don't engage til the rear spins right? well, when you hit that jump or hop, or whatever causes the back wheels to spin faster than the front, it engages the front wheels. At 30, 40, 50, 60 mph speeds that is a hard slap on the shafts. One of three things is most likely wrong. No promices but this is where i would start

(1) The left or right drive shaft is bent
(2) Left or right cv joint shaft is bent
(3)***** MOST LIKELY***** The prop shaft is twisted out of index.

The yokes are offset to correct the angle between the rear and front gearcase. You put enough pounding engages on it and the yokes will twist. Sometimes it can warp the shaft but you can't always see it. When this happens it creates a vibration that you usually can't feel. But the vibration travels through the hubs and with enough rpm that it creates a magnetic feild and somehow causes the clutch to lock in the hub. If you can put it on a lift, put in 2WD and with enough speed, it will do it. My scram would hit on both wheels at high enough speeds but only the left at lower speeds. No promices, bu I hope this helps