OK, I need your help. Have a 68 cuda which has developed a harmonic vibration at 45-50 mph. Had the tires rebalanced, the drive shaft and u-joints checked and spun, All good. When we restored the car, I had the original 727 rebuilt and matted up to a crate motor. You can feel the vibration in the seat and the steering wheel. Any thoughts would help. Thanks
Vibration?
- Thread starter JamesH
- Start date
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Had a small block crate motor from Indy installed during restoration. Had to have the lifters replaced in this motor twice due to them installing the wrong lifters. The correct lifters are now installed, thanks to Comp Cams.
cudamark
Well-Known Member
So when did the vibration start? Right after the engine install? 360 crate motor? Old engine a 318? Did you put in a 360 weighted convertor?
1968FormulaS340
Well-Known Member
If you have the car in neutral and hold the RPMs at the same RPM the car is turning at 40-50mph do you still get the vibration? (sometimes this helps identify the problem area, other times it doesn't)
I see you mentioned tire balance, but did you have the tires closely inspected for belt separation? (have had several threads with separation causing similar vibration in the past)
Are you sure you have the correct flywheel/flex-plate? Internal vs external balanced engine.
Have you checked the wheel and axle bearings?
Did you have the car correctly aligned (with modern specs) after the restoration?
Were the suspension components checked/replaced?
I see you mentioned tire balance, but did you have the tires closely inspected for belt separation? (have had several threads with separation causing similar vibration in the past)
Are you sure you have the correct flywheel/flex-plate? Internal vs external balanced engine.
Have you checked the wheel and axle bearings?
Did you have the car correctly aligned (with modern specs) after the restoration?
Were the suspension components checked/replaced?
You all have given me some places to start looking. The vibration started a few weeks after the restoration was completed. The motor is a 360 stroker motor from Indy and was internally balanced. Prior to restoration the car was involved in a rear end collision at 50-55mph. This sent the car sliding sideways down the road and ended up in a ditch. The impact from behind submarined us and drove the entire drivetrain forward 8 inches, broke all motor and trans mounts and both rear shocks. During the slide sideways the tires rolled all the way to the rims and there was stones and twigs embedded between the tire and the rims. I did replace the two rear tires.
The car was restored completely (10 months), spent several weeks at the frame shop and was brought back to spec's. Regarding the motor, It came with a harmonic balancer installed. The flex plate from the original 340 (Internal Balance) was used and matted up to a TCI Street Fighter torque converter. The vibration seemed to lessen when I installed the new tires on the rear. I am leaning to the wheel bearings. Will let you know.
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