Help with rear

[PNR Welding]

OK to start with, I blew all my teeth off the ring and pinion gears doing a 5500 launch drop. They were motive gears. So I ordered FRPP 410's and had them installed.
Here is where we need some help.
My mechanic installed them and he put the car back together and called me saying that its not ready cause he is getting a noise coming from the rear, you can really hear it when you push the clutch in at like 35 mph. He took it apart and shimmed it up differently this time. I think the first time was .006 and the second time it was shimmed to .014. This is where it is at now.
He put it back together and it is still making the noise. I put like 300 miles on it and it still makes the sound. The driveshaft feels loose, but the pinion isnt.
I took it out on the parkway and at 70mph it makes an annoying whine. It is so much louder than my motive gears. Something is not right.
Im looking for any suggestions on this. He took it apart and replaced the pinion seal and we are stuck now. He is also waiting for a tool to measure hanging in lbs to tighten the pinion gear before it moves. Can this be the issue? He as done plenty of them so I dont think so, but maybe.

 

[marcspaz]

The Load Pattern is wrong or the tech didn't torque the carrier bearing in right.

The most common issue with humming is the pinion depth is wrong and you are riding the outside of the ring gear. This causes the backlash to appear too loose while the car is on the ground (turning the drive shaft) but feels just right on the lift turing the ring gear while the dial gauge is attached.

The only way to know for sure is to pull the dif cover, clean 100% of the dif fluid out, and put pattern checking grease on the pinion. Spin the R&P setup 1 full turn, then take pictures of the coast and drive sides of the ring gear.

Go in the house and go to http://www.drivetrain.com/ringpinioninstal.html

The Pattern Interpretation Section of the page will help you understand what is wrong. Then, go tell the tech...

 

[marcspaz]

Oh, I almost forgot. I have been through 8 sets of R&Ps on my Jeep and Mustang in the past 5 years.

In my own experiance, once they start humming, even if you do a re-install and set it up right, the hum may get better, but it never goes away and you will have early EOL.

Kind of disapointing when you got a grand wrapped up in parts and labor and knowing it's never gona be right.

Have fun finding a good shop. I went through 3 different shops here before I finally did it myself. Not only did I get it right the first time, it was a good excuse to get some cool new tools and I still saved hundreds every time I did a front-end / rear-end rebuild.

I let the Ford dealer do my last install on the Mustang because of a dealer warranty that was too good to be true. Honestly I was expecting them to screw up too, but I caught a good or lucky tech that day.

 

[PNR Welding]

Hey thanks. We checked the wear pattern with the grease and the pattern seems to good. Neither too much on the outside or the inside. Hopefully we can get this right this time!!!

 

[n0nleft13]

Good luck on getting everything working Paul. When I drove by the other day I couldn't believe sick it looks with those tires on the back.