Whine / Howl Coming from the Rear End Area at High Speeds

[Coz]

I know this is a pretty old thread, but I’m have a very similar situation.

Would there be a specific reason you asked about the hard launches?

My story differs a bit:
2012 boss 302 with 10k miles. 2nd owner, bought 2 years ago with 7500 mi. WAS all stock and went to the drag strip and experienced what I’d call pretty significant wheel hop. Had been thinking of lowering and control arms so this sent me to do it. Boss 302 lowering springs and BMR poly panhard bar, UCA and LCA. Instantly experienced a loud howl from the rear basically as explained in the OP. Went to differential shop in Springfield, MO and he replaced the ring and pinion with ford parts. No change. He warrantied the work and put a 3rd set in. Still not much of a change. After this all happened driving down the highway I get a low humming above 70 which turns in to a warble above 80. This may or may not have been there prior to the ring and pinion change but I sure didn’t notice it.

So my questions are, would wheel hop potentially cause others issues that might result in the low tone rumble/warbke, like damage to bearings that wouldn’t have been replaced with the R and P? Driveshaft damage? Or any other thoughts why 2 new sets of gears are still really loud?

Thanks for any thoughts anyone might be willing to share!

Would there be a specific reason you asked about the hard launches?

It's because my car started whining after I took it to the drag strip. No wheel hop, just hard launches - well...as hard as a stock 6R80 will allow.

 

[Dave_W]

Check the driveshaft center bearing and its housing for play.

Going from rubber bushings to poly for the trailing/control arms (especially the upper) will naturally transmit more vibration into the bodyshell, creating more NVH. If you still have the stock lower arms, maybe try swapping them back on for a quick test to see how much the noise changes with the stock rubber bushings. I'd expect the upper arm bushings to make the biggest difference, as the UCA is connected directly to the diff housing and will pick up much more of the natural gear whine - that will get damped some by the axle tubes by the time it gets to the lower arms.