Front Diff howl 4.10 gear swap

[Maine-iac]

A few months ago I got 4.10 gears put into my rig. Everything seemed great until I put it in 4WD and noticed a howl/vibration above 30ish MPH while coasting/steady speed or decelerating. While the gears are under load everything feels and sounds fine. Do the gears just need to be broken in? That's what I thought at first and have expected the issue to go away. Well it hasn't. I changed the fluid and it was very Metallicy. Can anyone point me in the right direction as to what's going on with the ol' girl?

[DaveH71]

Incorrect installation, take it back to the shop and tell them to do it right. No diff should howl or whine ever, at any time.

 

Fluid from a new diff will have a small almost not noticeable amount of metal in it but it shouldn't look like glitter paste.

 

A whine during decel would most likely be incorrect pinion preload.

[slee3247]

Speaking from experience, it's difficult to properly setup gears without the correct tools. Without a pinion depth gauge, it's more or less "getting close enough"...take it to a shop that specializes in gears.