Rear end noise

[mopodge]

rear is a 7.25". I just swapped my 2.76 gears for a set of 3.90s from Motive Gear. They were buzzing or growling or whatever you wanna call it pretty good and when i got under 10 mph i could actually feel the vibration. I pulled the cover off and the axles out and reset my backlash by putting white grease in the ring gear and turning it around. The pinion teeth seemed to be making contact right in the middle of the ring gear teeth, like the picture shows. I am still getting the noise, but i can't feel any vibration at any speed anymore. The noise occurs the loudest during decel but also during accel. I'm using 80W-90 oil. The contact pattern looked right so do these gears just need to break in maybe? Should i switch to 80W-140? Btw, the car hauls *** with the new gears lol. Keeps the tires loose all the way through first but lets 'em catch just in time for the 2nd gear squawk.

 

[moper]

When you went for a test drive, and felt a vibration that was "in time" with any noise you felt, you should have stopped immediately and had it towed. The proper way to build rears is to go thru a non loaded break in period. Meaning, once you have replaced EVERYTHING including the ring and pinion, and the backlash, pinion preload, and resulting pattern is good, then you seal it up, fill it up, and run it on jackstands at 30-40 mph for 15 minutes. If it's noisey, or gets hot to the touch in that short time, you may have an issue, and can address it before any damage is done to the gear surfaces. You then let it sit and get totally cold, and then test drive it, with no hard acceleration. If it's quiet during that, you let ic cool off, and you're good to go. I'd say, if you clean all the oil off the ring gear, and look at the teeth, and see any type of wear pattern after a couple miles, the gears will never be quiet. No noise is perfect. A tiny amount of noise is ok. Any more than that, regardless of ratio, is wear that will eventually hurt the gears.