Open car cowl shake?

[Tom Coughlin]

I just wanted to add that, based on my experience, not all open cars shake, rattle and roll. My '65 (floors replaced in the '80's) has only had occasional shake due to specific problems which were found and solved. Most of the time it has been just as tight as a coupe.

[Thomas Sottile]

Try to find a tire balancing machine that can balance the wheels on the car while spinning them

[David Jones]

If there is no apparent shake or vibration on my coupe and I use the wheels and tires on the cab then surely I have proven it is not out of balance forces.

[Martin Benade]

That is mostly true but the coupe is more ridged so it would take more force to shake it. The cab body might be having a resonance the accentuates the problem. Regardless it does seem like you have done plenty to rule out all the usual suspects. The fancy balancing with weight on the tire, or grinding the tires true sound like the only remaining options. Only a few have similar trouble, I would not say it is the nature of the beast.

[Jay Darlington]

i''m wondering about the road surface, I don't think there's a highway in the U S that's smooth. any ripples or small bumps are going to shake an open car were an closed car will be smooth. we came home from Alaska last year and took the Cazar hi way in Canada, they had just paved that summer a section of it about 80 miles long. it was absolutely the smoothest road I've ever been on. you can't believe the difference between a new really smooth surface and an old surface.
Jay D.

[Jim Nelson]

Seen this behavior in two different cars; one turned out to be the sway bar bushings, and another turned out to be the rear torsion bar rubber bushings. In both cases, the rubber hadn’t aged particularly well.

[David Jones]

I have not checked the rear bushings and I do have a light clunk from the left rear at times like the noise you get when the brake backplate is not tight. (How do I know that?)