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Joe Tondu
07-26-2017, 08:07 AM
1950 Champion

I replaced all three U-joints but didn't pay attention to putting the yokes back the way they came out. Seems like there is a vibration now that wasn't there before. Any way to fix this? I don't see any obvious index marks.

Bud
07-26-2017, 08:44 AM
There are no index marks. The drive shaft is out of time meaning that all three of the u joints must be absolutely in line with each other meaning that all of the joint end caps must be aligned with each other or the shaft will have a horrible vibration especially at certain speeds. Bud

Joe Tondu
07-26-2017, 05:02 PM
And how is this fixed?

Bud
07-26-2017, 05:38 PM
The front half of the drive shaft can't be adjusted without welding, but the rear section can be removed and the shaft can then be re positioned on the spline to get the end caps aligned between the rear u joint and the center joint. Bud

Dan Timberlake
07-27-2017, 08:06 PM
This picture shows how to orient the yokes on a typical 2 piece driveshaft .
http://67-72chevytrucks.com/vboard/attachment.php?attachmentid=1063174&stc=1&d=1361310101

Only possible when the driveshaft has a splined connection between the ujoints.

It is still possible to install any one end 180 ° from the original position and change the original centering a little bit, which means the balance will change too.

Turning one or the other rear wheels with the car in neutral and in the air often will rotate the driveshaft and allow watching for runout, wwher a high spot might indicate a "heavy" spot, and placing a hose clamp with the head opposite the high spot is an interesting experiment.

Using a piece of chalk to locate the dynamic high spot is also sometimes useful when playing balance tech with hose clamps .

doofus
07-28-2017, 06:51 AM
If all else fails remove drive shaft at rear and turn 1/2 turn and reinstall. Luck Doofus