Need help finding a Vibration...

[skeeters65]

Car is a 1969 Camaro.
LS1 with a T56 stock clutch 40k miles.

The car had a vibration at 80mph. So I had the drive shaft re-balanced and now the vibration is at 90mph. So I figured the drive shaft was one of the problems. Now to find the other..

-The vibration is speed dependent and not RPM dependent.
-The rear end is a brand new Moser 12 bolt.
-Wheels were balanced when the tires were mounted 600 miles ago and all the weights are still on them.
-The vibration IS NOT in the steering wheel or brakes but CAN be felt in the clutch pedal.

Thanks
Any ideas??

[silver69camaro]

My guess would be the driveshaft still. Can it be felt through the shifter?

[Vegas69]

Have you checked you driveline angles?

[megaladon6]

does the vibration change if you step on the clutch or put it into neutral with the clutch engaged? does it matter what gear you're in?

[skeeters65]

Have not checked the driveline angles other than when we installed the rear end.

It does it in any gear when at 90mph or higher..

Dont think you can feel it in the shifter..

The vibration does not change if you push in the clutch put it in neutral..

Thanks

[Vegas69]

It's driveline angles or wheel balance. I'd check the wheels first or put some dyna beads in the tires.

[skeeters65]

Vegas,

What should the pinion and trans angle be??

What are Dyna beads??

Thanks

[Vegas69]

The driveline and the pinion should be parralel or within .5 degrees. // You need a angle finder. You can use a socket on the u joint caps. You can also use the harmonic balancer.

Dyna beads are ceramic beads that go to the lightest area of the tire and balance it.

[skeeters65]

I did a search on the Dyna Beads..

They seem really neat. Have you tried them??

[Vegas69]

They are in my motorcycle and car. The definitely smoothed the bike out. I didn't notice a difference in the car but I was chasing down a vibration and it wasn't the wheels. You have to leave your wheel weight on a car wheel to use them.

[BonzoHansen]

I never heard of them. This FAQ jumped out at me:


Why don't you have a chart for regular passenger cars?

We don't market to cars and SUV's due to the high performance style of those tires, which are low and wide. These types of tires commonly exhibit varying degrees of lateral imbalance due primarily to the width. This type of inbalance can only be corrected with carefully placed wheel weights. So that means that while Dyna Beads should not be used as the sole balancing method for these tire types, they can be used as a supplemental method designed to smooth out the ride and provide little or no future rebalancing.
That being said, we have a lot of dedicated Corvette, Hot Rod, Porshe, BMW and Mercedes customers using them with noticable improvement in combination with existing weights.
Check the amounts here (http://www.innovativebalancing.com/LowProfileTires.pdf).

...

We strongly advise against using Dyna Beads in any vehicle used for racing, for any application involving cornering at high speeds, or in tires placed under high acceleration beyond normal highway use. (drag racing, etc)

[MonzaRacer]

Call around and look for a shop with a Hunter road force wheel balancer, and have them redone with roadforce option, also you may need to match mount tires to wheels. Both can cost a little more.
I really see issues with Goodyear tires and Toyos, Kumhos, Sumitomos, Hankook(from china). These are the ones off top of my head that I have seen real out of round issues with. OH and any of the crap Cooper tires from thier china plant. Hankook had some decent tires till they started making them in china and when Cooper declined expansion of Kentucky plant and spent 1.7 billion building a major plant in China the quality now sucks even worse.
Good Luck
Lee Abel
AFTERMARKET PERFORMANCE

[megaladon6]

one other thing to try is jacking up the rear and bringing the tires up to the target speed. no, it's not the safest (make sure there's NOTHING in front of the car and you have plenty of room to stop if the car comes down) but it does eliminate certain aspects.

[kp.touring]

One other question for you is what type of driveshaft steel or aluminum? Aluminum or carbon are the smoothest shafts because of reduced rotating mass.
As already stated check pinion angle and tire balance first before going down the driveshaft road. One other thing to be made known is that most driveshaft shops can't spinned a a shaft as fast as we need when using a over drive transmission, do the math let say you have Viper t-56 with the 50% over drive and your engine rpm is 2000 the driveshaft rpm is 4000.
FYI back when 4 gen Camaros and Firebirds came out with 6 speeds and customer had a vibration problem the fix was an aluminum shaft.

Kevin

[Vegas69]

I never heard of them. This FAQ jumped out at me:
I'd never seen the data on racing. Thanks Bonzo.

[BonzoHansen]

I'd follow what these guys are saying. Rebalance the rear wheels, looking for runout as well. Are the rims hub centric?

Check the drive line angles. If in the ball park try rotating the driveshaft 180*. I've been told this can help in some situations but have not seen it myself. Also check axle runout & axle/bearing play.

[skeeters65]

Thanks guy.
I am going to check or try all of this Saturday..
Been real busy doing some re-modeling on the house..

Someone local had told me about putting the car on jack stands and getting it to target speed.. Well my target speed is 90+MPH.... I definetly am not going to do that.. SCARY!!!

[JEFFTATE]

Have the wheels and tires balanced on the car.
Find a competent shop that can do this.
It will help..

[skeeters65]

The car has a steel driveshaft and it has been re-balanced.

I checked the pinion angle and it was off so we added some shims and now it is right on..

Still have a vibration..
Might have a bad U-joint for the pinion angle being off??

Going to check the wheels this week...