So about 2 weeks ago I got ballsy an wanted to see how the car would do from a dig since I put the supercharger on. I launched at about 4000-4500 an the she spun through 1st so I eased of an caught 2nd then ran her through 3rd. Well since then I'Ve been hearing a ROAR coming from under the car. Having gone through 2 stock Diffs before the first thing did was check my Diff fluid for anything out the ordinary, It was damn near perfect an still purple. (R.P.75-140) By the way I have a Puddymod Stage 2 Diff w/ 4.44's now, with Excedium diff collars and T1R axle spacers. So I then moved on to the axles, no boots were torn and they appeared to have the typical play at the Diff. I then checked for any wobble in the wheel for the wheel bearings and found none. I even rotated the tires to see if maybe they were out of round or out of balance, but did nothing to change anything.

The noise is at its loudest when barely on the throttle an gets quieter when off the throttle and when on the throttle but is still present. It is even noticible when in neutral coasting to a stop. I dont hear any grinding or crunching sounds. Theres not really any vibration or atleast any more than what I get from the collars an all the reinforcement I have under the car. I think I'm getting in to territory that might me over my head. I just wana rule out the "Big Fixes"
(Tranny or New Diff)


Any insight is welcome at this point.


Heres a video of the ride home from work w/ normal highway speeds.
(sorry about moving the phone around so much, trying to get where its the loudest)


http://www.youtube.com/watch?v=eng4baXhxdQ

<iframe width="420" height="315" src="http://www.youtube.com/embed/eng4baXhxdQ" frameborder="0" allowfullscreen></iframe>

 

It roars 'cuz it's so beast! I hope you figure it out.

Need an extra hand, let me know.

 

Sounds like a bad tire to me. Hard to tell without actually being in the car myself. You got anyone you could swap rears with and take a test drive?

 

My diff sounded like that when it was on it's way out. Lift the car up on 4 jack stands, start it, and put it in first gear. Get down and listen and you will find your answer.

 

I swapped the tires it still does the same thing. car only gets driven on the weekends an on nice night to my softball games.

 

Sounds like the diff to me. Take the care to a mechanic you trust and have them check it out. Goodluck!!

 

 

have you checked trans fluid had a friend with a mustang that sounded like that and it was an output shaft bearing just a thought

 

will do thanks for the heads up.

what should I look for if it is the bearing?

 

I can't watch the video at work, but I had a similarly described issue in my 05 and it was the tail shaft bearing. It is a tapered bearing on a helical gear shaft....which is why it loads and unloads the bearing (in drive or coast). This causes it to make noise in one condition and not (or less) in the other. Pull your center console and the boot/foam over the shifter, you will know very quickly if it is trans related.

Also, keep in mind that even with the clutch in, the tail shaft is still synchronous to the wheel speed. So, clutching in and out should not change the frequency, but maybe the amplitude.