MrBlack2012GT

Hello everyone. My father purchased a manual 2012 Mustang GT premium off the lot last month. Black w/ saddle leather seats, manual, stock rear gear, tach redline glow, ambient lighting/mycolor etc., shaker 500 audio, sat nav delete, rear spoiler delete, stock rims/tires/brakes and it's impressive, apart from a very loud, very annoying vibration around the rear window/trunklid at speed.

The vibration starts at around 100 mph, in any gear, at any rpm. It vibrates the entire rear window and trunklid area. Sitting in the back seat and pushing on the rear window by hand when the vibration starts has no effect. I'm wondering if any 5.0 owners have had this problem or if anyone in general has heard about this? Thanks.

- Matt

bakerjd

Why do you need to go over 100mph?...


Don't really know what the cause could be. LCAs, UCA, rear sway bar?...have you got under the car and looked for loose bolts in the suspension? That would be where I would start.

Was it used?...maybe check the tires or look to see if the lug nuts are to spec?

808muscle

Warranty. Take it in.

BlackShelbyGt500

re balance the rear tire maybe.

MrBlack2012GT

It was brand-new, off the lot. There is no suspension noise while cruising around town, no rattles, squeaks, knocking or anything out of the ordinary, if I had noticed something like that, believe me, id be under there checking every nut and bolt within two minutes, but that's what is strange about this, everything is rock-solid. Until you get up over the speed limit a bit then something within the trunk or rear facia or tail lights etc. starts vibrating.

What we're thinking is air pressure gets into the trunk at speed and makes one of the plastic bits vibrate extremely fast against the trunklid, or something of that nature. The cause of the noise always seems to be air moving quickly through the car. Anyway I just thought i'd ask, maybe someone had the same problem with their 5.0 and could enlighten me on the subject.

300HorsesAndCounting

Over the speed limit in a mustang? Who's ever heard of such a thing? Haha. But my 06 Gt had a rattle by the back convertible window even at normal speeds. Never found out what it was but it just went away. How long has it been going on. Could it also be on a bumpy section of road? Do you go on the same road every time you decide to go over 100?

Nuke

Since when does NEED have anything to do with it?...

Absolutely take it back to the dealer under waranty. It's possib;e the wheels wwere never balanced properly, you threw a weight, yada yada. Insist that they do a RoadForce balance.

Young_Gun

In my 07 v6, I got vibration at and above 100mph just because of air resistance. You are pushing a lot of air at that point, and these Mustangs have the drag coefficient of a brick.

BlackGT45th

Maybe you just need to put a giant wing on the back!

In all seriousness take it in to get it looked at.

MrBlack2012GT

I've sped in different locations, highways in different states etc. and it doesn't seem like smooth roads help. We just got the GT brand new last month, it's not a convertible. We're taking it in this week. I honestly don't think it is anything mechanical, the car feels perfect until you get up to speed, and even with the vibration it still feels the same, it is loud and annoying but you can't feel it as though it's something like a tire or suspension component etc., you can just hear it, even over the shaker 500 speakers lol, hopefully i'm right and it's just a piece of plastic or trunklid touching something somewhere becuase of air pressure.