rear diff howls when coasting

[mopar jack]

Installed a used gear set and it whines when coasting to a stop. Running an 8 3/4  2.94 gear in a 742 case. I replaced all bearings and the gears looked good and seemed to be set ok with my limited tools and experience. Am I taking a risk in driving the car?

[Chryco Psycho]

not really but the gear set in not set up correctly / the pattern has already worn in on the used gears & they are not in the same place they used to be

[Cuda Cody]

   It's the gears or wrong pre-load.  You'll need to take it apart and check the pattern.

[Cuda Cody]

Depending on the amount of noise and what's causing it, it might not do any damage if you drive on it a bit.  But something is not right and it's best to get it fixed.

[1 Wild R/T]

I try to keep used gears in their original carrier with the original pinion shims.... I've swapped lots of sure grips into open 3rd members, just check the backlash before you take it apart & put it back to the same number... New bearings with the same pinion depth shim in the same case....

Putting used gears into a different case is always a gamble, I've had perfect patterns on drive & coast howl & I've had so-so patterns be dead quiet....  I've had better luck with 2.76,2.94 & 3.23 gears being quiet than 3.55 & 3.91 gears....

New gears... Strange & US Gear I've had very good luck with, Richmond has been hit & miss.... The old Zoom gears I've set up three sets & they all howled even though the pattern looked great....

[mopar jack]

The gears and case were together when I bought it but not in a vehicle so don't know how they performed. I replaced the pinion and carrier bearings and reused the shims. measured the pinion depth and was off .002 inches and let that go because the tool I used was not the most precise. Measured the pinion preload  according  to service manual and was good with that and set backlash at .007 inches. The pattern with the yellow paste  seemed ok. I have changed carriers between gear sets and never had a problem but this is the first time I pulled a pinion and it may be just highly used gears.

[mopar jack]

Thought I would try a highway gear (2.94) before I spent big bucks on a Gear Vendors. 

[1 Wild R/T]

I know the backlash spec is typically .006-.010 but on a used gear set I measure what it has worn to & set it back to that.... And it tends to be in the .010-.014 range.... Tightening the backlash is likely the cause of your noise...

[mopar jack]

What do you guys use to pull the diff from the housing with no lift laying on the garage floor? I've pulled and replaced a lot of diffs with a floor jack but now the jack I have doesn't seem to work. Also at 67 years young I have become very cautious of bad things happening under the car!

[RUNCHARGER]

I still drop them onto my chest and roll them off to the side of me. Darn things are hard to steady on a jack. I'm only 61 though, probably not going to pull and replace many more of them.

[GY3R/T]

   I always have the wife do this.      Next weekend i'm having her move the 440 blocks to the shop attic.