3rd Gen Poll: Rear End Noise howling when feathering throttle

brad, do your wizard maths and tell me if 55-60 it would be 400hz because mine sounds like this:
https://www.youtube.com/watch?v=rXu61z8yiMc

 

400 Hz sounds like mine too.

 

Sounds about like mine, but now that I am listening to the 400Hz, that sounds more like it. Maybe my math was a little off.

 

That's about right on.

 

I think we are getting somewhere. Next, someone needs to get a clean recording of the rear end noise.

 

This is my first time coming back to this thread in a while and I'm just like:

 

Incidence of Absolute Pitch is about 1 in 10000 in the general population... long odds that we have one with that gift among us. The frequency puts the note around a G4 or G4#. If someone knows someone with that gift it'd be settled right quick.

 

Neat little app

 

The biomechanist in me says "bravo" sir

 

So put in new Redline Synthetic 75W85 Gear Oil and no change maybe a hair quieter but i doubt it. When i drained the stock fluid it looked great very fine metal on drain plug but its normal. I guess im just going to live with it or have the radio up a little bit more if i drive in the 50's.. So dont waste your money replacing the diff fluid.

 

I was hoping you were gonna say it made a big difference...

 

Thank you for trying for us.

 

I changed mine a few months ago and had no change either.

 

Did a similar calculation. Mine is a 4.30 ratio and happens at 55 thru 65. I believe mine was the 2nd order of the gear mesh...which makes sense I suppose. I made the assumption that the 4.30 has 10 tooth pinion. I assume the 3.91 is an 11 tooth.

 

Nah, this is engineering. Pure science results in no useful product....engineering is the practical application of said sience to some useful end .

 

I was hoping the Manual Rears would not be having the same issue.

 

Dunno If its a Problem or a slight annoyance. I am doing a ride along with a service tech Friday for a rumbling driveline vibration. I will demonstrate the diff noise and get it documented. At this point, Im not gonna push for any sort of component replacement or in depth work. The driveline vibration is my bigger gripe. only happens between 60 and 65 and when fairly cold. Im guessing they wont have a clue on how to fix it....but I will ask for the steering wheel vibration damper at least.

 

There's a tsb for the "driveline vibe when stopping" I'm sure you're aware.

 

Curious... what frequency did you calculate, and what frequency are you hearing?

 

Well...I forgot to write it down. Did the calcs when I was in my truck. I thought mine was about 850 hz, which is why I was thinking 2nd order of the gear mesh. To me, that makes sense because likley the tooth coming in to mesh and the tooth leaving could be happening at two different times....ie 2x the speed of the pinion.

I need to do it again and see if I can measure the frequency. I use an app called frequensee which is a real time FFT