59 with a 40 mile per hour plus vibration

[390 man]

 59 has a vibration problem. It starts at 40 miles per hour and gets worse from there. I put the car up on the Hoist and removed all the wheels. I will have them road force balanced. While the car is off I figured I would have the drive shaft rebuilt and balanced. I will also install a new carrier bearing. This assembly has been removed before, is the U joints have Japan stamped on them. As I was removing the drive shaft through the tunnel, I found 2 1/8 inch thick spacers lying in the tunnel. They are approximately an inch or so in diameter with 3/8 of an inch hole. I'm just wondering if these were some type of an alignment spacer that should have been underneath the carrier bracket? When looking at the bracket after removed, there is no evidence that the spacers were underneath the bracket. I'm thinking that possibly the person that installed this carrier bearing forgot to put the spacers under the carrier bracket. Has anyone ran across this sort of thing before? Thanks Dave R.

[dplotkin]

With a two piece driveshaft as you have on your 59 pinion angle is vital to avoid vibration. Have you done anything to change ride height, such as new springs or "air choks" as we called them in high school?

The center bearing can be shimmed to adjust pinion angle relative to the front shaft to try and dial it out. On Chevrolets the single upper control arm mount is also shimmed, not sure how Cadillac did it. Have you looked at the shop manual trouble shooting guide for this?

Dan

[390 man]

Yes I looked at the manual but did not see anything that pertain to this. It just seems odd to me that these were laying in the tunnel. They seem too  thick to just be washers

[savemy67]

Hello Dave,

As Dan mentioned, there are several angles that need to be within specification for the '59 drive lines.  My 58, 59, 60 Chevrolet manual/supplement details the measurement of these specs.  Adjusting the specs includes the use of shims at various locations including under the drivesahft center bearing.  Check your other '59s for the use of shims under the bearing (except the Buick, which I think still used the solid torque-tube instead of an open driveshaft).

Christopher Winter

[390 man]

Thank you. Yes, my driveshaft shop confirmed how important alignment is. I will install the road force balanced wheels and tires, and rebuilt and balanced driveshaft. To start I will not install shims and see what happens. Thanks Dave.