C2 Driveline Vibration

[Gordon Peterson #4961]

Happy Valentines Day!

My '63 with Muncie 4-spd 3:36 rear has a vibration (slight drumming sound) when load is removed from the drive train such as when decelerating. I know it's the drivetrain because it vibrates in time with the car's movement, not with the engine. I did the usual check for looseness - nothing obvious. I had the rear bearings checked. One was a little loose, so I had the bearings on both sides replaced - no change. I tried re-positioning the propellor shaft on the diff yoke by 180 degrees, and this actually helped! But the vibration is still there. So I had the propellor shaft balanced and was told it is spot on. I was also told not to bother balancing the half shafts because of their relatively slow rotational speed. Finally I did notice that there is some lateral play in the slip yoke hanging off the Muncie's output shaft - not a lot, but I am running out of things to check. I've gone to my manuals and can't find any spec for lateral play in the slip yoke although I have seen reference to setting it to where you feel "a little play" when measuring for custom drive shafts. Is there a spec for lateral play in the slip yoke? Or is there anything else I can check to stop this vibration?

Thanks!

Pete

[Joe R.]

Re: C2 Driveline Vibration

Pete,

After owning several 63's, I know your pain.

You have found the problem already. That little play in the rear yoke of the 4 speed will let the driveshaft vibrate. The fix could be as simple as replacing the bearing in the tail shaft. Check your yoke and look for wear grooves where it contacts the tail shaft bearing. It should be smooth and fit the new bearing closely.

There should be no play in the output yoke. Check the yoke and make sure that it has been machined properly. I had one that was machined to one side and that made a vibration which could be felt readily.

Good luck,

JR

[Gordon Peterson #4961]

Re: C2 Driveline Vibration

Thanks, JR!

You mention a bearing in the tailshaft. I am aware of a bushing in the tailshaft to support the tranny output shaft (no play there, thank goodness!). Are you perhaps referring to the oil seal?

There are indeed grooves on my slip yoke approximately where it encounters this oil seal. Is this fit between the oil seal and the slip yoke what controls and minimizes lateral yoke movement?

Sounds like I want to replace this oil seal and find a new slip yoke.

Pete

[Joe R.]

Re: C2 Driveline Vibration

Pete,

You are going to have to replace the bushing and the yoke to get satisfactory results. You might find somesone to weld up the yoke and maybe chrome it to specs as the yokes are getting hard to find. At least the Corvette yokes with the u-bolts and nuts.

Good luck,

JR

[Craig S.]

Re: C2 Driveline Vibration

Gordon - there is a bushing in the tailshaft behind the oil seal tha supports the yoke, this is the wear point JR is refering to....Craig