Ok heres the story i put 3.73 richmonds in my 10 bolt last year and they blew this year from putting on to wide a tires.So i went to the junk yard that a good friend owns and found a 12 that they just took out of a 84 camaro,Yes someone already did all the fab work for me sweet.I checked it inside and out before i put it in and everything looks great bearing gears which i am almost positive are aftermarket.I take it for a ride for the first ride last night and those gears whine pretty loud,on accel ,deccel,coast all the time over like 40mph. I cant move the pinion what so ever so i am pretty sure there is enough preload on it cuz i changed the pinion seal and just turned it a little more than it was before and it felt nice.I also put in sphoon lca's at the same time.why would it whine like that it sounds like a school bus rearend.My only thought is cuz its a 12 bolt and the gears are bigger and they are aftermarket which i know most of them whine.Any thoughts or suggestions would be great.

 

Time to pull the cover and paint the teeth. My 12 bolts and even the 14 bolt are quiet as can be except over 120mph then they whine like a mother. You should have a little play on the pinion before it catches if not the mesh is way too deep.

 

the backlash is perfect i checked it out.I will try rolling the pattern and see what i get.