I'm getting a loud whining noise while the throttle is pressed. I took it to the dealer and they are telling me it's my pinion bearing do to the wrong angle. This truck is a 17 platinum with a 6" lift. Does this sound right because I know a lot of people with lifts and they've had no problems

 

 

Mine makes the noise anytime I'm giving it gas soon as I let off the gas no noise.

 

Doesn't look like this is good topic but here a progress report. Took to another dealer found the dif full of metal so they are replacing everything in the rear end. Under warranty

 

Lifting it generally doesn't put a strain on the pinion bearing, what it does put a strain on is your u-joints in the driveshaft if you don't adjust the pinion angle. Every vehicle is different and every one reacts to a lift differently, but ideally you want your angle at the pinion (measured between the driveshaft and the differential) to equal the angle at the transfercase (measured between the driveshaft and transfer case). Not sure what the options are in the F150 world for making adjustments, but in the Jeep world we either drop the transfercase down an inch or so, or we shim the axle 1-3* depending on the amount of lift. Shimming the axle points the differential back up in the air and lessens the angle.

The most common issues people get with lifts are vibrations and shimmys (especially when taking off from a stop) if your angles aren't good. This is because the u-joints are binding due to the severe angles. It's a good way to wear out u-joints quickly as well.