cs2015

Hello All,

I'm new. This is my 5th 'Stang. I have never had problems with the previous ones. This is completely out of left field. Especially for a car that is 2 1/2 years old. It has no mods. It has the performance package, manual trans and I drive it like it was meant to be driven.... I love to drive these cars!!!

I'm reaching out looking for some answers from experienced owners.

About 2 weeks ago I noticed that at highway speeds my car, 2015 GT, seemed to be acting wacky. When I would pass someone on the highway I felt like I was going to literally fly off the edge of the road. I thought I was losing my mind and figured I was having a brain fart of some sort. The rear of the car seemed "loose" and it felt like it wanted to go the opposite direction of the front. Crazy...

I then noticed that it picked up a loud "thump" in the rear. Very noticeable loud thump.

I kind of let it go for a few days thinking it might go away. (Not smart, I know) I was nearby the dealer where I get the oil changed since the selling dealer (still under warranty) is 45 miles away. I asked them to check the tires and give me an opinion. They said it had to be the tires and go to Costco for a re-balancing. (Tires purchased at Costco 1.5 years ago) They never checked anything on the rear suspension. They did tell me my tires should be replaced soon due to tire tread wear and they'd be happy to give me a price.

I just got back from Costco who rebalanced the tires. They said the tires are fine and they do not need to be replaced yet-they said the tread is uneven and they swapped them and did balance them. They said I should have a diagnostic run on the rear for suspension. They said something is definitely wrong with the rear and that is creating the thump. They heard it pulling the car into the bay.

Does that sound right? I drove home with that thumping noise again worrying that I was going to lose control of my car.

It does not feel like I'm driving my 'Stang, it feels like I'm driving an old school bus suddenly. The back is swaying all over the place.

Any ideas would be greatly appreciated. I did search the forum and didn't find any threads on this.

pure_kaos

What kind of uneven wear is on the rear tires? Inner, outer, middle? Is the thumping constant, like thump thump thump? Could be your rear diff ring and pinion out of whack. Block the front wheels, jack up the rear of the car so that both rear tires are off the ground. Make sure the car is in neutral and free spin the wheels with your hands and listen to where the sound is coming from. That should give you a good idea of where to start.

cs2015

Cpthair

I second kaos's potential diag, especially since it goes away when you corner. You're changing the rate at which the gears are turning between the sides. Could be misaligned.

Derf00

Does the thump increase/decrease with the speed of the car or is it at the same rate regardless of speed? Is it only one side? One side is most likely a bearing or axle shaft.

If it's on both side or in the middle of the car, it's diff related.

Hit any curbs or run over anything with the rear that you can remember? Perhaps a pothole that caught you just right?

cs2015

I took my car to the dealer I purchased it from. They discovered the bearing in the rear was broken. They said it was dangerous to drive since the rear tire was barely being held on. The service advisor didn't know which wheel since the technician just wrote down it was the "bearing ang tire ready to fall off" on the sheet he gave him. They got me a loaner.

I felt like the tire(s) in the rear were ready to come off as I drove to the dealer yesterday-definitely a white knuckle experience.

Gotta admit- never heard of bearings until I googled it. ��

Cpthair

@cs2015 glad you got it there safely! Gives a whole new meaning to "drive the tires off of it" Hahaha.