1966 Roadster Vibration

[Joe DeAngelis]

I have a moderate vibration noticed mostly under acceleration. The shake seems to move from side to side. In an attempt to eliminate it, I have done the following: new wheel bearings, new u-joints and balancing of the drive shaft, wheel balance, new ball joints. The car also has recently gotten a new fiberglass leaf spring and Monroe Sensa-Trac shocks. The car is a 327-300hp 4sp, NCRS Top Flight 2 times. I am thinking next to pull the 1/2 shafts and balance them with new u-joints, check the motor mounts and any other rubber isolators in the driveline.

Also, the car incurrs a second, less noticable vibration at higher speeds (50mph and above) that seems to be unrelated to the first. This is more of a shuttering or high frequency vibration I can feel in the floor under my feet.

Before I get into some major stuff like the flywheel or engine and transmission internals, does anybody have any thoughts on what I should do next?

[George C.]

Re: 1966 Roadster Vibration

Joe,

This may sound really basic, but you did not mention tires or wheel balancing. Could it be that a wheel weight has fallen off, or just a bad tire?

George

[Pete Wolff]

Re: 1966 Roadster Vibration

Is your exhaust system coming in contact with anything under the car ? This could happen wheen the engine torques over during acceleration. Check engine and transmission mounts as well.

[Dan Pepper]

Re: 1966 Roadster Vibration

George has a good point - my '66 coupe had a funky vibration, turned out to be a separated tire belt (Firestone radials - go figure). Suggest you check the tires/wheel balance - and sooner the better as a sudden tire failure wouldn't be pretty - for your fender or your shorts.

Good luck.

[Joe DeAngelis]

Re: 1966 Roadster Vibration

Thanks for the suggestions. To George and Dan, I replaced two sets of new radials and had them balanced with weights on both sides of the rim. With the vibration being aggrevated with acceleration, I am thinking it is more likely in the driveline or a rubber mount. Hopefully, it's a 1/2 shaft balance or u-joint problem. I had the drive shaft balanced with new u-joints.

[James G.]

Re: 1966 Roadster Vibration

A very common vibration problem on all manual transmission Corvettes of this era ( C-1 thru C-4 ) is the installation of "Aftermarket " clutch assemblies. That and flywheel balance problems.

When new, flywheel and clutch assembly were all balanced. When you buy a new clutch assembly for the new C-5 cars, it all comes in one package ( Flywheel too )

Let your friendly Chevrolet dealer get the correct parts.
Save the wave.
Jim

[John H.]

Re: 1966 Roadster Vibration

Joe -

Doubt if the half-shafts have anything to do with it. A frequent culprit for rear-oriented vibration, particularly under acceleration, is deteriorated bushings where the nose of the diff mounting bracket attaches to the frame. When they get old and sloppy, they allow the pinion nose to rise, upsetting the operating angle of the rear "U"-joint, and in some cases permit enough upward movement that the "U"-joint hits the underbody. If that's the case, don't replace them with the Harry high-school-hyped polyurethane set - they're all the wrong size, wrong diameter and length, the spacers and sleeves are all wrong too, and they'll just make it worse. Get an OEM rubber set and replace exactly as shown in the A.I.M.