Gunner823

iTrader: (2)

Ok, so, I've owned four thirdgens in the past, and just bought a near-mint 1987 GTA with 52K miles. But a slight problem has popped up. At highway speeds I was getting the dreaded vibration, so I replaced the tires (which needed replaced anyways) got a full alignemt, had the suspension checked, etc. But the vibration still exists, although its very slight and intermittent.

So, this morning I decided to drive it to work, and as the air was fairly cool, I had the windows rolled up. And the first thing I notice is....no vibration. None. 65, 75, 85, 95mph...smooth as silk. I roll down the windows and there's the shake. Now, I do remember my old 89 GTA having a similar issue, but it was a hard-top and it made more of a "noise" from wind resonance than actually making the car shake.

Has anyone experienced this, and if so, is there an easy solution (besides having one or both windows rolled up)? Yes, the car is t-tops, yes, they are locked and secure.

Untamed

Is the center bar secure? Sometimes the windows rolled all the way up, provide just enough rigidity to keep other things from vibrating. If the center bar isnt secure, that might be the cause. T-tops would still slide into the bar and lock even if it wasn't totally secure.

A second reason could be the window guides inside the door. They might not be completely secure to the subframe of the door, allowing the windows some additional play. I would think though that you would see a lot more vibration on the windows themselves if this was the case.

Lastly, if its just a slight feeling of vibration at speed with the windows down, you might just be feeling the wind over the seat belt.

GTA4ME

Have you done anything to your driveshaft? I changed the u-joints on mine and put it back on without rebalancing it. It made a funny vibration too. It was gone after I balanced it.

Gunner823

iTrader: (2)

I'm down to that. It's the only thing I haven't addressed. Ive had new tires, alignment, balanced twice, brakes, and it's still there. Things like having the windows up or having another person in the car seems to have an effect on how pronounced the vibration is, which leads me to believe it's something around or underneath the cabin of the car. i.e. driveshaft.

HalfInchWrench

Windows up/down and ds should have no effect on each other. At least in my time.

I'd check out the front end, wind resistance + starting to wear front end components could be enough to make it noticeable under specific conditions. Blowing around the car a bit. Check ball joints and wheel bearings ect for play. Check the whole front end Allignment guys may not have.

Check all rear end suspension too. LCA bolts, sway bar bushings ect.

Get under there grab and shake strongly cept for the ball joints, need a bar for those.