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Vibration at 70+mph. Tips needed.

Sesshomurai

Hey guys,
I am having an issue I need help with before I take it into Ford. I am getting a vibration in the car at speeds of 70mph+. It comes through the steering wheel
and is pretty steady. Also, at VIR this past weekend, the car vibrates/bounces at very high speed. It's not a rotor or brake issue because I'm familiar with how that kind of vibration affects the steering wheel and that's not it. It's whole car vibration but I feel it in the wheel is what I mean (not side-to-side vibration).

Couple points:

1) I put lowered springs on the car since previous track days (where I didn't notice the vibration)
2) I put a flexible rear wing on the car
3) I put camber plates on the car.

I first noticed the vibration on my way back from Summit (not during). Someone thought it my be an unbalanced wheel which makes sense if
a wheel weight got tossed off. I also thought it might be aerodynamics, but removed the rear wing and still get it, starting at 70mph.

Any idea what this might be?

thanks. Got 3 more track weekends and what to fix this problem.
 
It's most likely a wheel out of balance. Are you running the stock tires? The other possibility is you picked up some rubber on one of the tires and it's causing the out of balance issue.
 
Wheel balance is my guess. Unless a wheel is a little bent. If it feels stronger through your ass, it is the rear. If it feels through the steering wheel, it is the front. You can try a Hunter Road Force balance to see if there is any issues with the wheel or tire (it measures run out and other stuff besides regular spin balance). I have had good luck with the HRF, on tires that just refused to balance on my Evo. On my X5, HRF found the bent rim that was causing issues, though it was too small a bend to find visually. But it is usually more expensive than a spin balance, so might want to try that first.


Also look if there are a lot of marbles on any of the tires, if so you can scrape them off. My stock tires pick up marbles worse than any other tire I have used, I was having ABS issues from how much I had picked up. I scraped them off and they went away, but they can also cause a bit of a wobble.
 

Sesshomurai

K. Gonna have the tire shop rebalance all the wheels tomorrow morning. I thought it sounded like this and hope that it is. If not, back to the drawing board.
 

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