I recently put a 10" fab-tech lift on my 2013 F-250. Ever since the lift was installed when I reach about 60-70 miles an hour and let off the gas I feel a vibration/grinding sensation below my feet that seems to be coming from the drive line or transfer case. My u-joints are fine. Has anyone had a problem like this?

 

What if you took the lift off and checked if you have the same problem? We don't know at this point if the lift is causing it or has some damage been done.

 

Man I can't take the lift off. I don't have any parts to put on it to make it stock.

 

one possible cause is:
what angle are the u-joints operating at? if the angle is to great the rear diff angle will have to be adjusted?


the driveshift torque change during hard accell and coast will lift and lower the diff changing the ujont angle....when you add in big lifts kits the angle can be to much. the angle change on a hard decell may be to much.


you realize that a u-joint does not turn at a constant speed. its speeds up and slows down will each rotation. the bigger the angle the greater the speed change...this causes a vibration through the vehicle.
call fabtech and talk to their techline

 

The angle at the front of the driveshaft needs to be within 1-3 degrees of the rear working angle. As primem suggested you will need to correct that rear working angle. Just hope no damage has been done to the diff pinion brgs or rear of trans.