Just finished installing my RE SF 3.5" tonight (no tire or wheel upgrade yet, just stock). While I was driving it around, I noticed that when I let off the skinny pedal I heard a sort of grinding noise. When I press the gas pedal back down, it goes away. Sounds to me like a bad u-joint. Any thoughts?

 

probably a bad ujoint

 

If you only hearing this "grind" when you put power down, It could just be a u-joint. If it continues get underneath her and look to SEE if you can find metal rub somewhere else.. a cheap spray of paint on a suspected area will wear/rub again quickly if you have a clearance issue elsewhere..

 

Ok. My thoughts exactly. I am going to try to pick it up today and try to replace it. I think it is the rear drive shaft at the differential u-joint.

 

Replaced both u-joints on the rear drive shaft and the problem seems to still be there, but maybe not as bad (it's hard to tell)? While I was removing the DS there was quite a bit of play in the rear end and TC. I could tunr both about 1/2-3/4" back and forth. How much play is considered "normal"? Any one have any experience with this. The noise sounds like chatter. Like when I accelerate the play moves and slams the gears together and when I de-accelerate the same thing happens in reverse. Also while driving, if I put the right amount of pressure on the gas pedal, I can get it to chatter continuously.