starbai

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.

J2L06GT

On your wheel studs there are little clip washers that hold brake rotors
on for assy line, factory wheels are cut out for these, some aftermarket
wheels aren't, very obvious with no wheel on, usually one per rotor,
you can take these off so wheel sits flush.

starbai

Thanks for that tip, I did notice that being mentioned in a post before I began any work on my car, and was sure to remove them before I put the wheels back on, so I'm positive that that isn't causing the issue.

SilverHoss

Ok, you say no vib. up until 65 MPH. Lemme ask this: if you speed up higher say 15-20 mph, does the vibration start to decrease again? In other words, is is predominate at 65 MPH, and if you drive far above and below that, it is less or goes away? If so it is imbalance. If the vibration just gets worse and worse the higher te speed, it is likely a bent wheel, of center wheel etc. like you mentioned. When you tightened down the wheels when you bolted them on, did you do it in steps? Best way is to tighten is a little at a time, in a star pattern and to even torque. I usually tighten all the lugs to finger-tight, then all to around 30 ft-lb torque, then maybe like 70 ft.lb, then 100 ft lb. That should make sure the wheel is centered and torqued evenly. And just remember, it could be the wheels as well, just because they are new don't mean they are true. I bought a new wheel that was slightly warped one time-took me forever to figured what the vib. coming from!!