Hey guys, got a little problem (I hope) going on with my truck and am hoping you guys can help me out. I have an 01 f150 4X4, I have recently noticed a knocking noise when I start to apply my brakes but once I press them in a little further it stops. I put the truck on the lift this morning and checked the front calipers/wheels and everything was fine. I went to the rear end and noticed ALOT of play in the rear wheels, you can push them forward and back about 2 inches without the drive shaft engaging. We are thinking this is where the noise is coming from but not sure if it is a bearing or what. I am hoping you guys have some sort of idea/tips for me as far as what it may be causing this. Also I have noticed that the truck tends to slip (kind of similair to a vehicle with an automatic break, when you let off the gas the break kicks on and slows you down) when going around 55mph on a curvy road, doesnt do it on the interstate just back country roads around here.

 

well you can spin the rear wheels off the ground in park without the driveshaft spinning

 

Only with an open differential, and they will spin in opposite directions. A LS will take considerable force to do this.