Why does trans make a clunking noise and seems to have brakes on when I engage 4 wheel drive and turn wheels . Is this normal? I have read that it is. terry

 

Are you trying this on dry pavement, and are you in 4wd HI or Lo? If it's dry pavement and you are in low, that is normal.

 

I tried in a parking lot changing to High 4x4. Going straight seems ok but when I slow and turn wheels it seems to start grabbing anh trying to stop. thanks for reply terry

 

That's normal for a standard part time 4wd system like in your Explorer. When turning, the front goes through a longer arc and needs to spin faster than the rear, but the front and rear are locked at the t-case so it can't. The "braking" effect is the result, until something gives to release the tesion (or windup). When traction is bad (snow, mud, ice), then the wheels can just slip. On pavement, hopefully the wheels slip, but you run a good chance that something will break instead.