So on Sunday I replaced seales for my axles and new oil, and I wanted to see how it felt, I went on a gravel/dirt road to test the 4x4. So with the 4x4 engaged, I drove it around and felt fine but when I tried to turn around I would make a normal right or left turn and the whole entire jeep would jump forward and reverse while turning and going about 5-10 mph forward. Any idea? I have been told one of my U-joints is going bad so is that what is causing this or something else?

 

using 4x4 on hard surfaces will cause this effect

 

Bad U-joints, or binding the joints at full lock, surface not loose enough for wheel slippage, this will cause binding in the diff and transfercase.

 

thanks

 

Yep, hard surface slippage. The tires are covering much different amounts of distance, outside turn tire: more and vise versa.

 

SSS: Slow speed slippage. No worries. When youre at a slow speed and turning "tight-ish" while in 4wd, it will jerk and jump like that.