I would guess it isn't defective parts going in each time, but defective installation. My '06 with 3.55 gears (original) is absolutely quiet. What about going to a different dealer?

 

i was told by diffrent dealer to work with the "offending" dealer to reslove this issue and let ford engineering do their "job" as for the status of the problem it is getting worse now it is grinding and whining. the dealer told me they still dont know what is going to be done and i am losing patience i even played with the idea of trading it back in for a rousch 427r i love the mustang i just want it to be right i sure wish ford could get their act together their customer service sucks

 

I tried one other dealer and it made noise too. It is either a paid to low tech problem or bad parts. After the Lemon Law deal Ford put in a whole new rear end and all was fine until the limited slip quit. With all the other problems I have had with this car (sterio, speedometer, seats, clutch, rattles, ebrake, etc) FORD QUALITY IS THE WORST. ALAN ( not Alex the old ceo) ARE YOU LISTINING?

 

well we are going on number 5 this week and also they are putting on the axle whine kit per tsb this time it is agreed that if this doesnt fix it they are gonna put another complete axle assy it was determined that it wasnt defective parts but defective installs
other wise i am trading it back in on a roush or shelby

 

FWIW. I've gone from super quiet stock 3.55's to frpp 4.10's that made noise back to the original stock 3.55's.

I took the 4.10's back to the shop that did them (big gear shop that owns warn) they said everything was perfect and that sometimes frpp gears whine.

Had a local shop install the original 3.55's and they are super quiet just like new. Talked to the owner/head mechanic and he said it took him awhile to figure out how to do a quiet gear install in s197's. He said he had a hell of a time with frpp 3.73's in particular. This guy doesn't let bad stuff out of his shop. He said he reinstalled the 3.73's 3 times for a customer before he got rid of the howl. His secret was setting the backlash tight. Anything above .008" and they would howl, .008" and the noise was gone.

 

Stock gears in my 07 GT were replaced twice with no improvement. Vibration dampers installed per TSB, still no improvement. Gears replaced third time, and no more whine. The dampers are still there, but I doubt if they are needed now.