1hotroc

iTrader: (3)

I feel stupid asking this question but here it is. I just installed 3:70 gears in my 9 bolt originally a 3:45 which was untouched and perfect. Anyhow after the install the rear now makes a howl noise at 45MPH and up during very light throttle conditions and can also be heard on decel. I did not change pinion depth because I did not know where to install the shims. Do the shims go behind the small or larger pinion bearing race or both? I also reused the original crush collar. Backlash is probably .005-.008 which seemed close to the silent 3:45's. I am a rookie at setting up rear diffs and i'm sorry I ever tried to do it. Any suggestions on setting up the 9 bolt would be a big help. Yes and I did do the search on FAQ on the 9 bolt.

Kevin91Z

iTrader: (1)

Take it to a professional and let him/her set up the gears. But it might be too late. Once they "set up" in the rear end and whine, they whine forever. It takes special tools and experience to set up a rear end that we regular people dont have.

hwcoll95

iTrader: (6)

almost sounds like pinion bearing,preload not setup right,i set mine too tight,and have no noise issues,but only have a couple hundred miles on it,pinion shim is on the gear side,but more crucial is side bearing shim for correct contact patch