just installed a 3.73 in a a4 lt1. did a little breaking in by letting it stay on jack stands and putting it in gear then letting it cool now when im on street when i decelerate it almost sounds like its grinding or whining bad. on acceleration it is fine the problem is getting louder and i have not even put 10 miles on it the backlash was good so was pinion depth. but carrier seemed a little tight but i could still turn by hand please help

 

What kind of gears are they? Richmond gears are notoriously loud.
Is it a 12-Bolt?
If no to those questions, the problem may well be backlash and pinion depth.
What did you shim it to?
I know places like Moser has a specs for their differentials backlash installation.

-Goose.

 

its richmond gears another thing is that the crush sleeve didnt take much effort to crush is it possibly not tight enough its a 10 bolt the shims wher smaller on the carrier and i used the factory shim on the pinion

 

I think its pretty common to have richmond gears to whine. My old 3.73's used to whine until i sold them to a friend. We tightened up the pinion nut again before putting the rear end in his car and they don't make a sound anymore. So that is something you could try i guess.

 

Did you tighten the pinion nut to the correct torque? Also, what did the pattern look like on the gears? Did you check the pattern?

Ken R.

 

the pattern was good what is torque specs on crush nut not really sure what it is any help