Has anyone noticed a clunk in the rear end when giving it gas from a stop to take off after installing a lift kit 7.5" by fabtech, I took it in to ford and they said there was so much power to the rear end that it was actually twisting the rear end so much that the 5" blocks would rock after accelerating and go back causing a clunking noise, does this sound right.

Mike

 

What truck do you have?

Mods? This info would be helpful

 

99' Ford F150 Supercab 4x2 4.2L V6

 

Any mods other than the lift?

 

It's called axle wrap. I believe many get it after installing lifts. I had it on my 97. It has nothing to do with too much power. I heard it can be taken care of with traction bars. Or they might be called something different for lifted trucks. But, basically a bar that connects from the frame to the axle. It will stop the axle from twisting under acceleration from a stop.

 

Try dropping the driveshaft and then add lithium grease in the yoke that the spline goes into. Just be sure to mark your driveshaft so they line back up. I have to do this every 6 months.