I now have a n 89 formula, 305 auto, I previously had a 1986 trans am, 305 auto, both cars vibrate badly! mostly felt in the seat, not the steering wheel. changed driveshafts on both and balanced all wheels to no improvement! Vibrates terribly from 50 to 85 mph. any ideas? thanks

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Tim

 

Hey,

Sorry if this is too elementary for you but...It sounds like either misbalanced tires or a flatspotted tire to me. If it's only noticable at the higher speeds, I'd check the wheel balance first. You can notice a bad flatspot as soon as you start rolling. Either way, You've gotta love it when that dashboard gets to dancin'


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Clem
SCCA TransAm Series Race Mechanic/CrewChief
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1983 Z28 with LG4, 5 speed, and (unfortunately) T-tops
1983 Z28, NO T-tops, (unfortunately) Auto Transmission (hopefully not for long)

 

Ive got the same problem with my 85 bird.
Changed to alum.driveshaft
changed both half shafts
complete new suspension including all bushes
hotchkiss panhard rod and trailing arms
New WHEELS AND TIRES
Different engine plus new trans and convertor
Subframe connectors and strut brace
Vibration still exactly the same
Powermite

 

i had a very annoying vibration right at 80 MPH (the vibration drops off considerably below 78MPH and above 85 MPH). rebalancing the tires did not seem to help. replacing all four tires did do the trick, and it was about time for new tires anyway.


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stephen - 89 GTA - https://www.thirdgen.org/rides/index...ew&rideid=1321

 

I had vibration problems too when I switched to 3.73 gearing with my T-5. Rebalancing the driveshaft got rid of most of the vibes. But, one thing to consider is that drive shaft vibrations are about 2500Hz or times per second, where tire/wheel vibration is about 750-800 rpms. The feeling is very different. The higher freq vibration feels like a 'drumming' sound. Where the wheel misbalance or tire carcus distortion can make the steering wheel shake back and forth. Also, a bad spark plug wire/miss fire can also feel like a vibration problem....

 

i have the same problem, my vibration starts around 60 mph and get worse on up till about 80, 85mph then levels out. havent found it yet, but i can tell you this. i have new tires had all rims balanced and it still does it. i found that my transmission mount was bad and am in the process of changing it. hopefully this fixes it. good luck.

 

To StephenC

What is the name and color code for your car. That color looks awesome. I am about to get my silver TA repainted and I think this might be the color. How much did it cost?
Please E-Mail me with response...


Sorry about being off topic. I don't know what all you people are complaining about. My car shakes, vibrates, jumps,bottoms out, and has a loud exhaust... that is the whole fun of owning a Domestic v8 and scring the Sh*t out of pople you pass by

-Max