Z28 top end shake

[94Z28]

guys-

Anyone got any ideas on what's wrong with this? My Z28 has a performance axle (which I don't think is the problem) and hitting speeds over 110 mph the whole car shakes enough for me to think something's wrong. Even when I put the car in neutral at speeds that high it still shakes. The car has 140,000 miles and I assume a rebuild soon to maximaze performance. Any speculations on the problem at hand (the shaking)? Thanks and let me know.

[StingRay_68]

More than likely it's your tires. Most tire shops will only balance a wheel to 65mph because it is illegal in most states to drive faster than that. At 110 your wheels are probably so out of balance that it causes the whole car to shake. Had this problem in my old vette. A new set of rubber fixed the problem pretty good though.

[BadAzz240]

Ok, for one I used to balance wheels and 2 of my best friends balance wheels also and I have never heard of balancing a tire to a certain speed. Yes, different tires have speed ratings but that has nothing to do with the wheels being balanced. Its either balnced or not. But my freind had the same issue after he put a new rear-end in his car. We tried everyhing different tires, rims, we even thought it might be the tranny cause that was new at the time also. But you know what it was... It was the U-joints that he put in at the same time as the rear end. They were new but for some reason it was making this horrible vibration at anything over 80. We replaced them with another pair just outa curiousity and bang no vibration what so ever. Hope this helps man.

[BasilisK 3 7 77]

I have the same problem in my '89 IROC. Once I hit about 90mph, I start getting a heavy humming/vibration from the right side of the car. At about 120mph I have to back off because it sounds like the car is about to break apart. Once I've hit those speeds, I'll always get a steady hum/vibration when I break to come to a stop (only on the first stop). Never have either problem under 90mph. Pretty aggrivating when you wanna see how hard your car will push when you have to give up at 120 with pedal to spare.....

[StingRay_68]

I used to bust tires as well... every machine we used sped the tire up to 65 mph.

Would you like to go back and read the instruction manual for the balancer?

[H22luda]

I work for Gm and I know that on some of the years of camaros there is a technical service bullitun out about a high speed shimmy. It was because of the driveshaft and it required that the existing drivshaft be either rebalanced or replaced.

[94Z28]

thanks for all the info-

I know that the tires aren't the problem, they are Z rated (over 149mph) and are balanced. I'm going to check the U-joints and the driveshaft, so I see if that does anything. Anyone else got more ideas? Post 'em. Thanks again.

[BadAzz240]

Originally Posted by StingRay_68

I used to bust tires as well... every machine we used sped the tire up to 65 mph.

Would you like to go back and read the instruction manual for the balancer?

Yea, after i posted i realized what you meant but the way you worded it, made it sound like you were trying to say something different...

[roadtrip120]

its your driveshaft, mine did the same thing but around 85mph, i got an aluminum driveshaft off ebay for $125. to my door. the vibration went away. if you want to check it switch your driveshaft with another camaro, thats how i found out. i checked around here and it was like $55. just to balance it, and they said when you change u- joints it could get out of balance, so i spring for the aluminum one.
good luck

[hot_red_z28]

Yes, I guarentee that your problem is your driveshaft. It is a common problem. It either needs to be balanced, or you should get a new one. I promise it'll solve your problem. That is also why it still shakes in neutral, cause the drive shaft keeps spinning.

The drive spins at a rate with the tires, that is why it only occurs at the higher speeds when the shaft gets whipping around...