I took mine in for a rear-end clunk and mentioned the whine I had on accel at around 70. They rebuilt the rear and now I have a whine on decel at 70 or so down to 50 or below. It is really not bad and the tech noticed it when he did the install and said if I wanted it done again to just bring it back. I don't really notice it and it has been months now. Once they do it wrong, they have to replace the gears to get everything right. They aren't supposed to re-use most of those parts.

They never did fix the clunk though. I am pretty sure it is my Steeda 3rd link bushing. If they would have just told me that, I would have left the stock version of the whine there.

 

Latest update: Took it to a different dealer (Capital Ford) - their tech was highly recommended by a local Mustang shop. They did TSB 5-20-2 again. Fixed the whine, but created a vibration at 75 mph. Took it back - they couldn't fix it, so they called the Ford engineer and he said to just put a whole new differential in. He apparently said that they used to do that frequently with the 05's instead of trying to put in gears because a high percentage of the gear repairs ended up not be fixed or worse. But they started allowing the gear work again because it costs far less to do that than replace the whole differential. So for those of you who have had gear related warranty work and your still having issues, don't just accept it. Ford is aware of the problem and if you are persistent, you may be able to get a whole new differential.

Now I'll just keep my fingers crossed that the new one is okay and that it's installed properly. And worse part - I'm stuck driving a Ford Freestar for about a week.

 

Hope the new differential does the trick. Sounds like you finally found a tech who wants to solve the problem . Keep us posted. And after driving a Freestar for a week, your GT should seem new all over again!

 

The friction modifier TSB is a different issue than the pinion gear missalignment.... that TSB about the friction modifier is a clutch pack problem....

 

My rear pinion/ring gear has been replaced 3 times. The service manager told me if this doesn't fix it they will install an entire axle assemble - which to me means the entire rear end - differential, axles, brakes, etc. I'm kind of hoping it goes bad again just to have everything new.

 

Be careful what you wish for. After replacing the entire differential, the vibration at 75 mph is STLL THERE. Not as bad, but still there. And to make matters worse, the new gears whine worse than the old ones. Going in Monday. I hate to say it, but I'm starting to think lemon law.

 

Sorry to hear you are still having problems . If I am reading your previous posts correctly, you didn't have a vibration problem until you had a TSB done. I'm wondering if they damaged something ELSE while they were doing it? FYI I had a similar problem on my '79 Fox-body (rear-end vibration at certain speeds) and it turned out to be a loose drive shaft.

 

If they disconnected the drive shaft, was it put back together in the same location or 180 degrees out of phase? I know another owner had this problem and by disconnectingthe drive shaft, rotating it 180 degrees and reconnecting it, the vibs went away.

Still, a "qualified" mechanic should not make that mistake!