Hey guys...

I did some work to my 5.0 finally this weekend. I'm left with an amazing looking car, but A LOT of vibration at 65+ mph...

I've been told that if the steering is shaking, then its your front wheels... Its not shaking at all...

The shaking happens at 65+mph, mostly felt through the floor board on the car... the passenger seat looks like its going to rattle itself loose lol.

Not a single vibration/issue can be felt below 65.

Now, given that much, I'm thinking that I can relatively narrow this down to the rear suspension.

First things done this weekend were 20x9 Shelby Razor Wheels on 255/35/20 tires. I know I can expect a harsher ride, but not this much vibration. The wheels were new and so I dont think that there are any bends or issues with the wheels themselves.

There were suspension mods done as well, later on in the weekend, including a Steeda Adj Panhard, and Eibach Sportline Springs.

The vibration was felt on the car BEFORE the suspension was touched. Meaning all else equal, rims only change from factory, is when the vibration was noticed.

Perhaps the suspension mods multiplied the problem later... but I dont think so as I dont feel it being any worse after the springs/bar was installed than it was before.


So given all that, here is what I'm thinking.

1. The tires may not be properly balanced on the wheels. I am considering taking the car to a shop to get them balanced again to see if that helps anything.

2. On any other car I've ever had with aftermarket wheels, I needed to use hub-centric rings to center the wheel on the hub before bolting it down. I was under the impression that this was not needed with the Shelby Razors.

When putting the wheels back on the car, it is clear to see that there is SOME play between the centerbore of the wheel and the hub itself. Its not a tight, snug fit, the way I've had when using these hub rings. The thing is the difference in size is SO SMALL that I can't see how using hub rings would even work... they probably wont be any thicker than a rubber band.

Lastly, I'm re-using the factory lug nuts. And in doing so, there's not much room to put a socket over the nut and into the wheel. its a VERY tight fit, and its kinda difficult to bolt them down while holding the wheel on dead center. There is enough play where if you move it to bolt it down, there is play depending on which bolt you bolt down first.

To help alleviate this I did what I've always been told, bolt them down in a star like pattern.

Even still I've a very good feeling that the wheel isn't perfectly centered on the hub.

The question is how do I fix this? If hub-rings are probably too big (even in smallest form) to fit here, would getting a smaller set of lug nuts help? I'm not sure how it would.

I know it was a long post, but to alleviate advice that wouldn't really help, I thought it was best for me to be thorough.

At the end of the day, I suppose one of the easiest ways to figure this out, is to put the factory wheels/tires back on the rear and taking it for a spin to see if the vibration still exists.

One other bit of information, the car has NOT had an alignment yet either after the suspension mods. It is on the list of things to do this week, but since this vibration was felt before the suspension mods I'm really thinking that it has to do with the wheels first and foremost. Id like to get some ideas as to what to do about this, so that when I take the car in to do the alignment I can have the same shop try to work on the wheels for me at the same time.

Thanks to any one who took the time to read through this, and I look forward hearing some advice.

 

Balance first. Rings second. You shouldnt be torquing them until it's on the ground anyway.

 

try taking the front 2 tires and bust them off and swapping them on the rims then rebalance them.

 

Pull the rims, and see if the retaining ring are still holding the rotors on the studs. If so remove these. The Shelby Razors have a flat surface by the stud hole. This will keep the rim from sitting flush with the rotor before tighting down the lug nuts.

 

What cobrakev said. Also move the front tires to the rear and the rear wheels to the front. See if you still have the vibration. Also when tightening the lug nuts tighten them a little at a time so they all seat properly. No rings needed with the razors. Did you buy the tires already mounted to the rims? Were they static or spun balanced?

 

Did you inspect the driveshaft?? Could be out of balance.. Just a thought

 

Do you have a tire shop in your area with the Hunter Road Force balancer? That is the best way to get your tires balanced. I've ordered tire+rim sets before that were "balanced" before delivery, and my favorite local tire store has the Hunter machine. Every tire+rim I've ordered always needed some adjustment.

If it was the drive shaft balance, you would have had the vibration before you changed the rims.

Be sure to check for those retaining rings, too. Take them off if found.

 

All I know is, the last time I rotated my wife's Jeep tires in he driveway with only a jack and a lug wrench, we had vibrations all throughout the car above 55 mph. Not sure what I did wrong, but lets just say I won't be doing that again. Have a shop do it unless you have the tools (for balancing and mounting) and the know how. It's worth it.

 

you would be surprised by how some shops rotate tires. You have to watch them too

 

Just a an update folks, I went to my local ford dealership because they offer the road force balance on the proper equipment. $100 for 4 wheels/tires, or $50 for 2 wheels/tires.

At first I only had them do the two rear. One was very badly out of balance to the point where the tech asked me if anyone else even attempted to balance it or did they slap the tire on the wheel and call it a day.

The 2nd rear was supposedly defective, and the machine wouldn't pass the balancing no matter what they did.

So I got the 2nd tire replaced by the first shop and had ford mount balance it for me.

They ended up doing a front two anyway for free... and rechecked the rear two.

The car is smooooth as butter now... well as smooth as can be expected for a mustang dropped 2" on 20" wheels... but no vibrations!

Thanks for all the suggestions/help folks! If you're experiencing this issue I HIGHLY suggest that road force balance, its leaps and bounds a better way to do the job than a regular machine and the proof is in the pudding as the car is completely vibration free all the way up to 100 mph (if not beyond, lol)

 

Glad to hear it!

 

I am having the exact same problems with my 97 cobra, I had my tires balanced by my buddy who works at a dobbs he reset the computer/scale every tire, even though you don't have to. The car seems to have the same vibration, I am just curious my car only shakes when you let off the gas, no clutch in no breaks on and no gas, it vibrates the whole car, not harsh but if you start exceeding 65+ it starts to get worse, I also have 410 gears, the only thing I imagine is something on rear end or driveshaft might be slightly off I also have 255/50/17's in the back and 245/50/17's in the front

 

I also just noticed your tires where the problem, so I'm still lost on my problem

 

Glad re-mounting fixed it.

'Cuz all this sounds like typical 2011+ EPAS issues with aftermarket wheels.

Went to the some of the best mounters in Queens, NY, still have random shakes above 60-70 MPH.

 

My car did the same thing and it was too much power to the driveshaft and components once I changed it to a one piece the vibration was gone

 

And if you chafed your driveshaft then u need to check you torque on the 8 bolts connecting the drive shaft the shoul be torqued between 75 to 80 ftlbs