>
>I need some input. I recently had my shop change out the gearbox and clutch
>in my '67 GT6. They also replaced the two u-joints in the drive shaft. The
>car
>now drives and shifts great, however it develops a high frequency vibration
>above approximately 50mph. This vibration is noticable but not overpowering,
>and is road speed-dependent (I push in the clutch pedal and there is no
>change).
>I called the shop and they recommended I have the wheels balanced - All I've
>done so far is rotate the rear wheels to the front (no change) and did a
>visual inspection (saw nothing amiss). Any ideas? The car is a non-OD model
> w/ a 3.89:1 diff.
>Thanks, Karl Theis
>
>
Karl,
Remember you have two more U-joints. If one of these is "weak", it will
cause a slight harmonic vibration.
Also, GT6s are notorious for the U-joint straps on the flanges
spreading and allowing the U-joint to move around slightly. This is not a
design fault, but more likely someone got over zealous in an installation.
Also, the sliding yoke on the differential end of the drive shaft must
be greased periodically. The yoke did not come with a grease zerk but, had
an allen head plug in it. If yours still has the allen head plug, install
a grease zerk and lube.
Also, I have seen the ends come out of the yoke which allows water and
dirt to get in the splines. I have had to make the plug since no-one have
it available as an individual part.
My best guess about the vibration is that the drive shaft has become
unbalanced. Being banged around while being out of the car and even
stones hitting it can cause this.
I just had a drive shaft shortened and balanced at U-Joints, Inc. and
was charged $32.00. This was for a hybrid project, But, I have had drive
shafts balanced after replacing u-joints several times trying to
eliminate a vibration.
Balancing seems to be the best solution.
Best Regards,
Tony R.
"GT6s"
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