Sometimes we see things we don't fully understand at first glance. I agree that it's always best to address a problem ASAP if you actually have a problem. The OP didn't mention any problems, just an observation that could have been exadurated by having the wheels off the ground. If he really had a true 1/4 turn of slop he would likely be hearing some noise.

 

Here's the shop manual for the rear axle...

https://www.scribd.com/document/7016501/Group-4-Rear-Axle#scribd

 

Thanks for the videos very informative.

 

I like a lot of play in rearends...but i'm pretty sure that's not what we're talking about here...

bad joke

 

When you check it that way , you are getting additional play from the spider gears as well. If the back lash alone allowed a 1/4 turn , the gear diff would sound like a fire truck siren. Check the "backlash" after you remove it from the housing but before you take it apart.

 

First rule: Don't Create Work For Yourself. If the rear end isn't clunking, whining or grinding, then you're likely seeing the play from the differential gears. Think about it, if you really had a lot of slack between the pinion and ring gear, you would hear it while driving. Now if you can wiggle the pinion left to right you would have a real problem.

 

I'm going to rebuild it with a new ring and pinion. With the wheels on the ground and the drive shaft out, I can rotate the yoke close to 1/4 TURN.

I found this video on Youtube that seems pretty good as far as "How To":

 

I'm going to rebuild it with a new ring and pinion. With the wheels on the ground and the drive shaft out, I can rotate the yoke close to 1/4 TURN.

Yeah you got something majorly wrong. If you had something like 4.10 gears and max backlash, you still shouldn't have more than like 1/8" of movement once all the lash comes out, which is something like 10° tops. 90° is basically about to explode.

Does the yolk have slop in any direction? Do you have any sort of noise?

The R&P aren't too hard to replace in an 8" or 9". You don't really even need a press if you have a vice. Worst part is finding a torque wrench in inch pounds at a reasonable price. I had to order a beam style on amazon.

Check your axle bearings while you have it apart. I had to replace mine.

 

.008"-.012" at the ring gear is Ford's spec for an 8" rear end.

 

You could turn the yoke at the pinion end of the rear axle housing 1/4 INCH, as in measuring the travel as if you had a tape measure glued to the dust shield behind the yoke? If so, that ain't jack. You're fine. Now, 1/4 TURN is a completely different story. Make sure both rear tires aren't moving, at all. If you really have 1/4 TURN of play your rear is on borrowed time.

 

Yes, that's a lot.