L76

I have noticed a rough sound (with some, but minimal vibration in drivetrain) in my 65 small block when I drive above 60mph. Car is a complete body off restoration. Everything in the driveline was balanced prior to install. Any ideas? I am curious - even if a drive shaft is balanced, is there a proper orientation for installation? If so, is it even possible to install "out of phase"? Don't know if this thought even makes sense, but I am truly puzzled on this... I'm starting to theorize...

Cheers,
L76

Procrastination Racing

Complete restoration?

Are you using restoration bias ply tires? Tire designs from 50 years ago do not ride like tires today.

Original type shocks? today's gas shocks take a lot of harshness out.

Yes, the drive shaft has a right and wrong way. Typically, they are so close that it is usually irrelevant which way you went in, but after a restoration, odds are any positioning marks are gone. Try changing it to see if it helps.

Clutch? I have found a lot of "new" clutches and flywheels, even though factory balanced, are not that close. I always balanced them before putting them on the race car and any I have had to replace in my street cars.

midyearvette

if you believe the issue is driveline related and not a tire out of balance, the usual suspects are u joints or the rear bushing in the tranny tailshaft or loose bolts somewhere......

L76

Thx guys. I don't think it's in/near the clutch because my problem only occurs at speed (not necessarily high rpm). As for the other variables - I have witnessed the problem on two different tire/rim combos (including a set of new Bridgestone Potenzas on new American Racing rims). I have swapped out shocks with new KYBs... And problem still there. I'll look at the driveshaft next, then U joints, etc. Thanks.

L76

66jack

Check the bushing on the Differential...it might need to be tightened or replaced!

jack