Rear End Again!!

[MasonWS6]

Just change the axle bearings yesterday that fixed some of the noise. But still when going straight getting off the gas it's singing to me. Not sure if it's the pinion or carrier bearings. The garage couldn't give me an answer but still charged me. What do you guys think? Also put Mobile 1 synthetic oil with the additive already in it into the rear. Should I stick with that or go to the conventional oil with the gm additive next time?

[Firebirdjones]

Can't say for certain without being there, but when you describe letting off the gas and getting rearend whine, that sounds like classic ring and pinion noise on the "coast" side.

Once a ring and pinion starts making noise on either coast-float-accel it's usually worn in there perminantly even after changing pinion depth and backlash.

If you don't have accessive backlash, and you don't have a pinion bearing on it's way out or a pinion seal leaking (another clue) Then I wouldn't worry much about the gear whine unless you are prepared to spend some coin on it.

Because to correct it would require a "setup kit" which is about $150, and another new gear set ($200) And then having someone set it up properly is the next challenge, which could be another ~$200. It may or may not be quiet depending on who/how someone sets it up.

All that effort isn't worth the trouble in my opinion if we are talking about the stock 7.5" rear.

[MasonWS6]

Alright thanks

[2002ssslp]

Start saving for an aftermarket rear like a 12 bolt or my favorite the Ford 9". If you plan on adding NOS, a turbo or supercharger and you have a 6m I would also look into the S60. For now, try the GM additive and conventional Dino gear lube. It is recommended over synthetic and will cure the " rusty screw " noise most 10 bolts have.

[pajeff02]

Certainly sounds like the gearset is worn. Are you running a tunnel mount torque arm?

[Firebirdjones]

^^^Yep, That's another piece of information to keep handy. Those aftermarket suspension pieces will transmit more noise throughout the car. A rearend that was once quiet can sound like a school bus with solid mount control arms and torque arm. Even just adding a poly mount on the trans tailshaft will transmit more noise throughout the car.

[Supershafts]

Your pinion depth is wrong and why you have noise on decel, so as bearings wear tolerances change, bearings lose there spec and on decel the pinions depth changes and causes noise.

If that was a driveline shop that couldn't tell you that, don't use them to fix the problem

[cammed goat]

S60 gets my vote.