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| Vibration at high speeds (Page 1/1) |
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va441975
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APR 21, 11:16 PM
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My Formula is very smooth but when it’s at high speeds I feel a vibration. The sides vibrate but not so much in the steering. The inner doors vibrate and you can actually see the aide mirrors both sides vibrating. It has brand new tires and the tires are balanced properly. Does anyone have any idea what may cause this. It’s done it on both sets of tires I’ve had on my Fiero so I know the wheels are not the cause. It only does this at high speeds.
Thanks in advance.
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Gall757
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APR 22, 08:57 AM
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If you don't feel it in the steering wheel, chances are it's somewhere in the rear. Axles and wheel bearings are suspect. The output bearings in the transmission may be sloppy. Grab the axles near the transmission and push-pull to see movement. Don't give up on the wheels and tires being out of balance. Most shops run the wheels up to 60 mph...if that. Ask around to find a true 'high speed' balancer. [This message has been edited by Gall757 (edited 04-22-2019).]
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andreww
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APR 22, 09:22 AM
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I always find swapping the wheels front to back as a good way to rule out balancing issues. If after swapping, the vibration moves to your steering wheel, you know it's a balancing issue.
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Shho13
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APR 22, 01:03 PM
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Could still very well be a wheel issue, a bent rim can cause a vibration that can not be balanced out. ------------------
"Discord"
Red 1988 GT under restoration!
Let's Go Mets!
( ͡° ͜ʖ ͡°)
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va441975
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APR 22, 10:40 PM
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Thanks for the replies. I didn’t realize that about high speed balancing. Appreciate the axle info as well.
The rotating the tires from front to back would be an easy first check to rule out the tires or rims.
If the rim is bent I’ve always seen it would not balance right or was picked up as being bent when they were balanced is that not always the case?
Thanks again!
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theogre
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APR 23, 11:34 AM
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If it have "Brake Upgrades" like infamous GA "upgades" for 84-87 sold by craptastic TFS or installed by DIYers then can have uncentered rotors that can vibrate like hell.
Trans can have iffy axle bearing or axle itself have bent etc can do same.
Both often worse as speed increases. Many times the trans axle seals leak when Trans axle bearing are bad but not always.
Could be Hub bearing problems too but often can hear and/or feel problem just by jacking and rotate by hand. When I had a bad hub, it only made obvious noise above ~ 50mph. Other have noise all the time.
See my Cave, Axle
Even if Static Wheel Alignment is perfect on a Bear etc machine, Dynamic Alignment when driven may have problems for iffy BJ(s) and/or other iffy suspension parts including bushings.
Example: Machine says X Toe is good but have bushing/rack problems making Toe out of spec while driving. IOW Machine toe spec is trying to guess when the toe is while driving. Just 1 iffy part and machine toe goes out the window.
Inspecting suspension parts often is hard even for good Alignment Shops. Parts you see may hind many problems like outer shell of most bushing can rot on hidden side that's very hard or impossible to see. Cheap borescope or even small mirrors may help to see the back side of many CA and other bushings. Check all BJs too. Often bad BJ only problems when completely unloaded. Bushing may do same unloaded.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave[This message has been edited by theogre (edited 04-23-2019).]
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va441975
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APR 23, 06:13 PM
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