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WHY are my Forgestars vibrating at speed??

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Hey guys I need some help. I finally got my Forgestar setup complete (F1419x10 front 19x11 rear), got my tires mounted (285/35/19 f and 305/35/19 r super sports) and had everything installed. Took it out on the highway and discovered they had an awful vibration at 70mph. Took them to a different shop, had them rebalance the wheels and tires (road force balanced) and make sure all the clips were removed from the mounting surfaces. It helped, but now I still get a vibration at 80mph+. What could be causing it and how to I fix it? It had none of these issues with the stock wheels a few days ago, so I'm certain it's something to do with the new setup. Any input is appreciated.
 
What Tracy said.
It can get pricey if you don't have the ability, or the connection, to mount/dismount the tires multiple times to pin point the defective tire, or wheel.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
Good to see you wrote: "Removed the clips from the mounting surfaces". By this statement I would think you're speaking of the 2 circular clips on the wheel studs used to keep the rotors in place on the assembly line. (Note: If this implies the original tire shop did not remove these clips when they installed your new wheel/tire package, then an inexperienced wheel/tire installer did the original wheel install.)

Factory wheels have relief cutouts to accomidate the stud clips, but your new Forgestar wheels do not. Definitely a source of viberation and wheel wobble.

Next, as the driver you can help to diagnose the location of the viberation, either front or rear wheel(s).

If the viberation seems to be felt in the seats, and/or windshield mounted rear view mirror, this would tipically indicate a Rear wheel balance problem.

If the viberation seems to be felt in the steering wheel and/or the brake pedal* this would tipically indicate a front wheel balance problem.

(* footnote: Front wheel balance felt in brake pedal with very light foot pressure. Not to be confused with warped front rotors felt with normal foot brake pedal pressure.)

I'm leaning toward, (hoping), it's just a wheel balance issue. But, what is the amount of wheel weights per wheel, the 2nd tire shop used to Road/Load Force balance each tire?

A good mount and balance wheel/tire set up will only require minimal amounts of adhesive wheel weights. As little as 1/4 to 1/2 oz and as much as 1.0 to 1.75 oz per wheel. If they needed 2, 3 or 4 oz of wheel weights to balance a single wheel/tire, then remove it, break the bead and rotate the tire 180 degrees. Then remount and balance.

Just a few thoughts, hope some of it will help you to ID the cause.

302 Hi Pro
 
Forgestars use centering rings and although I know people leave them off if you're not using them I would install them. I had the opposite happen. I used the centering rings with Enkei wheels on my Boss. I forgot to remove one of the aluminum centering rings and crushed it installing the street wheels. I got a nasty vibration as well so I pulled the wheel and realized the centering ring was still on the hub. You can bet I didn't let that happen again. ::)
 
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Please elaborate on these centering rings needed for forgestar. I don't have them on mine and never noticed an issue. (With that at least)


Sent from my iPhone using Tapatalk
 
Proper wheel fitment includes being hub centric. What that means is the manufacturers have a specific size for their hubs and their wheels fit them with the same size center bore. The S197 and S550 Mustangs use a 70.5mm bore. This thin spacer is used between the wheel and hub for a tight fit. In theory the tapered lug nuts will center the wheel and most never have a problem. Centering rings are available and I use them when using non hub centric wheels. They usually come with wheels that are not hub centric or you can buy them from various sources including nice affordable aluminum ones from Tire Rack. When originally looking at Forgestar wheels about five years ago they were not hub centric but that may have changed.

@Surfergeek just bought a custom set of CF5's. Did they come with centering rings?
 
125
123
Thread drift-We have been using hub centric wheels for 25 years in the heavy truck world, nuts have integrated washers, no tapered nuts anymore, good stuff. Figured the auto industry would have adopted.
 
I just got a set of CF5's in June and they came with centering rings. They're my track wheels so I don't bother with the rings, but if I drive with them on the freeway they do have a slight vibration but from the sounds of it nowhere near what they OP experienced.
 
6,363
8,187
M91196 said:
Thread drift-We have been using hub centric wheels for 25 years in the heavy truck world, nuts have integrated washers, no tapered nuts anymore, good stuff. Figured the auto industry would have adopted.

They actually did..for awhile. Ford went through a bunch of recalls/ wheels replacements in the mid 90s because of this..great idea though.
Also the OP might want to have the wheels torqued and then retorqued when they have heat cycled, probably not the issue, but a cheap fix if it is..
you may try using the old fronts,... then rears, to double check if it's a front/ back issue.
 
72
65
Exp. Type
HPDE
Exp. Level
5-10 Years
New Jersey
My Forgestar CF10s came with centering rings. I have left them off while testing certain things and didn't notice any vibration, but I also didn't get the car up to any real speed at that point. I leave them in normally.
As others have said, try to determine where the vibration is coming from. I'd also try to get some Forgestar centering rings to try out.

Also, does it get worse while braking? Could be a rotor.
 
VoodooBOSS said:
Proper wheel fitment includes being hub centric. What that means is the manufacturers have a specific size for their hubs and their wheels fit them with the same size center bore. The S197 and S550 Mustangs use a 70.5mm bore. This thin spacer is used between the wheel and hub for a tight fit. In theory the tapered lug nuts will center the wheel and most never have a problem. Centering rings are available and I use them when using non hub centric wheels. They usually come with wheels that are not hub centric or you can buy them from various sources including nice affordable aluminum ones from Tire Rack. When originally looking at Forgestar wheels about five years ago they were not hub centric but that may have changed.

@Surfergeek just bought a custom set of CF5's. Did they come with centering rings?

My CF5s that I had custom done came with centering rings. Forgestar are 72.56mm and my centering rings that came with the wheels are plastic. That reminds me I was looking for some aluminum/metal rings to put in there. .... Aluminum and plastic rings are readily available. I just ordered the following aluminum rings:

https://www.amazon.com/Coyote-Wheel-Accessories-72-7050M-Aluminum/dp/B01BYDQ15O/ref=sr_1_3?ie=UTF8&qid=1472709631&sr=8-3&keywords=72-7050A

Could have some a little cheaper, on eBay or elsewhere for Aluminum, but I like the RED color as I am less likely to forgot it or leave it on the hub or generally have it missing or put somewhere it shouldn't be. And Amazon Prime.
 

DEye

You can't get there from here...
Do you feel it in the steering or car in general ?
Too bad you didn't go for a square setup, you could rotate them front to rear and see if you could feel it more /less...

It could also be a marginal tire.
http://www.tirereview.com/when-is-it-overkill/
The section on tire contribution was a reminder for me that many things about a tire may not be perfect.
 

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