Whenever I have the 4 wheel drive engaged in either hi or low and turn the wheel, the truck hops or shudders. If I go straight, nothing happens, only while turning and in 4 wheel drive. Any ideas on what may be wrong? I have a 98 Explorer.

 

What may be wrong? You're using 4H and 4L on a surface with too much traction. Apart from the control-trac 4auto setting, your 4wd system is like any other part-time 4WD system. When it's in 4H or 4L, the front and rear are locked together so they can't differentiate. When you turn, the front needs to spin faster than the rear, but it can't. Under low traction conditions, the wheels will slide to make up for the lack of differentiation. Under higher traction conditions, the wheels hop (or something breaks) to make up for the lack of differentiation.

 

MrShorty gave the answer I was about to give as well. The other possibility is that you also have different size tires front and back (different brands can actually vary quite a bit) and it does not take much of a difference to causes binding on the 4WD systems. I know that on my old Subaru (a while back now) it was an issue when I had it in 4WD and the tires were different brands (pronounced when turning, but occasional when going straight). Even in the snow I could feel it shudder every now and then as it hit the limit and forced a slip at the wheels (i.e. there was still too much traction to allow for sufficient slipage to prevent binding).

 

I recently was pulling out of a gas station when the rear tires slipped and i felt the front engage with a loud clunk. since theni noticed my explorer shuddering and now making clunking sounds when turning in 4hi, nothing in the straight driving and nothing in 4auto. i dealer says everything checks out. im not sure if i should go for a second opinion.