I have both rear wheels off the ground with a jack under the differential to check for bearing play. Driver side is good. Passenger side has some play but not in the bearing. The side yoke moves in about 1/16" when I pry up on the trailing arm. Is this ok?
68 Vetteman

 

1/16" is a bit much. You're through the hardening and it's wearing away the unhardened material off the end of the splines.

Before tearing everything apart you should disconnect the spring and half shaft and measure the yoke play with a micrometer, just to be sure it's really that much play.

 

100%

BUT...as I tell my customers that have the same issue where the side yokes have wear. I tell them that the 'beginning if the end' has begun. And if they only put 500 miles a year on it...then they can have fun and enjoy the car and take time to save up for the inevitable.

What you DO want to check is the clutches in the differential. With the rear raised up off the ground. Using a torque wrench. Set it to 40 lbs/ft. Have your transmission in park (if an automatic) or in first gear or reverse if a manual transmission. Put the torque wrench and socket on your lug nut and apply pressure. IF the wheel turns and the torque wrench does not click...your clutches are worn out.

NOW...make sure you understand this if you are not aware of it so this test was performed CORRECTLY.

When you raise your rear end of the car...the suspension drops. When it does this...it can cause the rotating drive-line to actually get in a bind...depending on how far down your suspension and drive-line dropped, SO.....before you go and put the torque wrench on and try this test. You have to make sure that your wheel and tire will turn in the direction that you are tightening the lug nut for this test freely. SO....manually by hand....with the transmission in NEUTRAL...rotate the wheel so when you KNOW you apply torque...the wheel will turn. THEN...put the transmission back in park ( automatic) or first gear or reverse ( manual).

DUB

 

Just got done with my test. Both wheels off the ground and 10 lbs of torque to keep the wheels turning.I put the trans in first gear and at 80 lbs the passenger side wheel still wasn't turning. Will the worn yoke chew into and ruin the differential housing? If the differential side yoke is worn on that side is the repair just to remove the rear cover, pull the "C" clip ,remove and replace with a new yoke? I will put on about 400 miles till the winter rest. Thanks
68 Vetteman

 

Only a severly worn yolk will chew into the housing. You should be fine driving 4 or 500 miles before winter sets in, but with worn yolks the end is usually mushroomed somewhat, and some pounding with a big hammer is required, or some grinding to to remove the mushroom end and then some more hammer work.....now you need to flush that case and get all those little chips out of there....this is where you can't be sure that you got all those chips out of the pinion bearing and the project snowballs into a full rebuild.
My suggestions are to choose your new yolks wisely....some of the junk out there looks good but doesn't have the proper heat treating and the yolk ends are soft. I have a set here that is well on it's way to mushrooming again with only 3 summers driving on it.
And if it goes this far, use Timken bearings.