JustAn0therNumb3r

So, my poor 2012 Mustang GT is at the dealer for the second time in two weeks. The first trip over there was due to a thunk/clunk noise coming from the front passenger A-Arm (occasionally occurs when backing out of my driveway), a leaky rear diff, notchy 2nd gear shifting, and my rear gears were whining LOUD.

So, the dealer had it for about a week and they replaced the ring and pinion gears (3.73). They were unable to diagnose the 2nd gear issues or the a-arm issue. I got the car back and it was driving much better, except there was major vibration at about 65-75 and then 85-90.

I had planned to just go ahead and take it in to let them balance the tires, but I noticed a new sound starting yesterday morning. At low speeds (around 20-25) I would hear this noise which sounded like a rock in my tire or the tire going flat. It was occurring at regular intervals so at first I thought it was a rock. Got out, no rock and the control arms don't move. So I took it to the dealer again for the balance and this new rear end issue. At first the technician was telling me that it was probably due to the straight cut gears, but then after hearing it realized it was something new. Haven't heard back from them yet, but hopefully it's not the same issue.

I was able to reproduce the issue by going up to about 20-25 in second gear then holding the clutch in. Didn't happen to get a video of the noise.

Has anyone had any similar issues with their '11-'12 GTs?

Entaille

I had the leaky diff deal too, they will give you a turkey baster to fix that. kinda funny / kinda sad for a fix.. but hey, it works.

sounds like they can't balance for crap - see if another dealer can road force balance it, if they can't resolve that part.

gears can be awfully whiny if not installed properly. not sure if that is what your noise is or not.

JustAn0therNumb3r

Strange thing is I haven't seen it leaking again since they replaced the ring and pinion. I've been going easy on it though, so that may be why.

moosestang

Sounds like they didn't put your driveshaft back in the same way it came out. Either that or it's their gear install causing the new vibrations. They should know better than to remove the drive shaft without marking it, but who knows.