Nuke

Your vibration problem could be one or combinations of many of those things described above. You'll have to try to eliminate them one-by-one.

The RoadForce balance will identify tire and rim issues that a standard spin balance willnot and cannot pick up. It applies pressure to the tire (hence the Road Force) as if it was making contact as it does during use.

Also, if you're running aftermarket wheels, be sure the rotor clips have been removed, IF any of them still remain. They were for the assembly line only and have no further function.

tdbrown75

What i have feels NOTHING like tire out of balance, it's not a wobbly shake your passenger seat kind of vibe. It's much higher frequency, imagine a bass box hitting a long low note, it's audible, its a resonance in the frame of the car VERY similar to exhaust drone only its not drone. It's a buzzing kind of vibe that blurs objects in the mirror. Imagine hitting rumble strips at high speed (only not quite as pronounced).

Here's my very similar thread I started when mine developed: https://mustangforums.com/forum/gt-s...ay-speeds.html

I'm only looking back into it as I decided the 4.10s are a bit much for me on the highway and the gears are a bit too short so I'm dropping back to 3.73. I'm secretly hoping it fixes my vibe problem too, but I'm not overly optimistic about it. Car goes in Wednesday where I should have took it for gears the first time. I'll be back with an update once I get it back. Wish me luck!

Tim

05slpGT

Exactly as described above. My rear view mirror looks likes its going to fall off when the vibration kicks in. Its a low deep audible drone, almost like exhaust. I would throw the GoPro on it but im afraid that the vibration would knock it off.

tdbrown75

So I called my shop today to see if all the parts had come in for my appointment this week. The guy at the shop told me the “GT500 bearing kit” had not come in yet but should arrive tomorrow. I was thinking why the heck do I need a GT500 bearing kit and is it even any different? I got home an Googled it… and almost fell out of my chair.

http://www.lethalperformance.com/for...stall-kit.html

Made specifically for the 2010-2013 Shelby GT500 this ring and pinion install kit is the answer many have been waiting for. The GT500 uses a different pinion bearing than the Mustang GT. Since the GT500 pinion bearing itself can't be ordered through Ford many have had to stick with the standard bearing which come to find out was the cause of vibration in the rear end after a gear swap.

So as I had a dealer do the install they very likely used the stock GT pinion, which in turn would explain why they could never identify the source of the vibration! I'll let you know how it turns out later this week or this weekend.

Tim

05slpGT

I wonder if that is included with the rear end in my car? I have this http://www.americanmuscle.com/frpp-s...mbly-0512.html
I had the vibration before AND after that thing was installed.

This is such a pain in the ***, theres so many things it could be. Heres a little writeup about symptoms of bad control arms
http://www.ehow.com/how_8054093_cont...placement.html
"Test drive the car on the freeway. Torn and worn out control arms or bent control arms will cause a car's steering to vibrate. This is a symptom that will become exacerbated the higher the speeds are and may become very noticeable at freeway speeds. Other potential causes of this symptom can be a bad alignment, bent wheels or unevenly worn tires."

tdbrown75

Yes that rear end should have the bearing (reads heavy duty bearings), so in your case at least that's probably not the issue.

It is pretty amazing how no one seems to be able to fix these things, you assume anything can be fixed now a days with computers/tools available.

Again I'm not getting my hopes up, the vibe is not the reason for the gear change but if it goes away I'll be thrilled.

If it doesn't fix it we shall journey on together until one of us figures it out. I find out tomorrow, wish me luck!

Tim

moosestang

Did you every turn the driveshaft 180 degrees or adjust the pinion angle yourself? Grab a couple of wrenches, crawl under there and change the angle. There is no correct pinion angle imo, there is just what works best for you. With the stock driveshaft or any shaft with a cv joint at the pinion flange, you can set it to almost any angle without causing any harm.

If I were a dealer and someone brought a lowered vehicle in complaining about vibrations, I'd tell them to go pound sand as far as warranty goes. Put the stock springs back in, then I'll waste my time with it.

tdbrown75

Yes I clocked the drive shaft (tried multiple positions) but no I've not messed with the pinion angle. I had the car lowered for 2+ years before putting in the 4.10s with no signs of any vibes at all which is why I am suspicious of the gears. Seeing as the dealer owned speed shop modified my car (suspension and gears) they stood behind their work which was really cool.

05slpGT have you tried various pinion angles to see if you could make it any better/worse?
And moosestang thanks for the tip!

Tim

05slpGT

Ive never adjusted the pinion angles, not sure how its done.

808muscle

I will put money that its your pinion angle. You need a adjustable UCA installed to adjust it. Do some searches. Dropping your car with a one piece driveshaft changes the PA so it has to be corrected.