can gear whine mess up the transmission?
ive driven a total of 20 miles with them now, and it whines the loudest when barely on the gas cruising, doesnt usually whine under acceleration not until 3rd gear anyways. and also if im totally off the gas coasting in a low gear like 2nd at around 2k rpms i can feel my shifter vibrating, is this normal? it never did that with my stock gears
My take on some of the questions and comments so far.
Rear end gears hurting the transmission: NO.
Gear Oil. Post stated the 2.5 quarts of gear oil were used. Consider that it may be OVERFILLED. The fluid level should be 1/4-9/16-in below the fill hole. This is not fill it up until it runs out. There has to be room for expansion. The car MUST be level. This means if the rear has been jacked up, the front must be as well.
Have you considered that which gear you are in shouldn't have any effect on the sounds from the rear end? In cases where the sound changes with the gear, its more likely the problem is in the transmission.
However, see you own comment about shifter vibration. Did you index the drive shaft and companion flange when it was removed? If not installed in the same relationship to each other, this could be the source of the vibration.
Will continued driving will hurt the car. IMO the answer is most likely no. The break in period for a new rear end should be hundreds of miles. At 20 miles, you have hardly used the new gears at all. Come back in a couple of hundred (or even a thousand).
I did listen to the video. They didn't sound all that bad to me. I did hear some change in pitch in response to drive line lash. However, that could have just as easily been the transmission.
If anything was done wrong it was how you set up the pinion depth. Not a good idea to assume it was the same as the gears removed. And since a paint contact check was not done, you have nothing to cross check your work to.
So if you are super anal, do a paint check. If the whine is only minor, drive it. Either way, check the fluid level.
>>From Ford Service cd for 8.8 solid rear axle.
1.66-1.77-liters (3.5-3.75-pints) 6.4-14.3-mm (1/4-9/16-in) below the bottom of the fill hole