Uneven axle shaft lengths on 8 3/4

[68suprB]

I pulled my axle shafts today and found that I have 2 different length axle shafts...It's a 68 super bee, 8 3/4, 742 casting. Originally a 3.23 rear (now 3.73), one shaft is maybe 1/4 inch+ longer than the other. Was this to compensate for the offset pinion in the 3rd member, or maybe the bearing adjustment? Or is it some used junk somebody threw in between 1968 and now? One is tapered a little different than the other, and one has 2 smaller holes in the flange w one big hole, and the other just has the one hole in the flange. Both are 30 spline and fit in ok.

I've been getting a vibration from the rear, we put the car on a lift and let everything hang and it looks almost like the U joint is binding sporadically...Everything is new in the 3rd member, new u joints, driveshaft and green bearings..Wondering if there is an issue w the axle shafts causing it. I know I'm kinda jumping around here but I figured I'd throw both of my issues out there...

Thanks for any input!

 

[Meep-Meep]

1/4" is quite a bit so I have no idea what happened there. Unless an axle is bent I don't see how it can contribute to vibration.

 

[68suprB]

Ya thats what I was thinking. Maybe one was snapped in the past and another was just thrown in there. I was in the car on the lift so i didn't see exactly what was vibrating but the guys that were watching it said the pinion yoke was bouncing up and down. Does anyone know what the original axle flanges looked like? 1 hole or 3 holes?

 

[67 coronet]

original flange was 1 hole.if you measured it corectally then one of your axles is out of a different rear for sure.by pinion bounce i am figuring they mean the whole rear and not just the yolk by itself.are your u bolts tight?no springs are cracked?

 

[68suprB]

Thanks for the reply. Everything is tight w new u bolts, the leaf springs look good too. You're right I think they meant the whole rear was wobbling, nothing crazy but obviously more than it should be moving. Brake drums are balanced and the tires/rims are brand new and also recently balanced. I would think the axle shafts would actually break before bending enough to make the whole rear wobble, but I'm pretty new to this, still learning from the older guys about the ins and outs of these cars...

 

[68suprB]

This is the odd shaft w 3 holes (not counting the lug stud holes) on the axle flange before I changed the bearings

 

[Kern Dog]

With the NON adjustable bearings you have, the axle shafts do NOT have to be the same length. The stock setup required them to be the same length because they both pressed against the thrust button in the differential and the right side adjuster was responsible for the end play. With the NON adjustable bearings, the splined end of the axles dont even have to contact the thrust button at all.

 

[Kernel Sanders]

Could one of the axles been cut to shorten when the greens were put on? Apparently a common thing to do instead of pulling the 3rd member out to remove the thrust button.

 

[Cranky]

Take a look at the axle ends and if they look different, then one has been cut.