8-3/4 open diff whining, wheels binding, pulled axle shafts, problem...gone?

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cudak888

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My '68 Satellite saw the road today for the first time (that I've had it anyway). Almost immediately, the following issues made themselves apparent:

  • Acceleration feels as if there's a load on the drivetrain, as if the parking brake is partially on.
  • Anything over 10mph gets the rear end whining like a banshee.
  • Shifting weight to the left of the car (right turns) would lessen the sound; shifting weight to the right would increase it.

First thought here was a ring and pinion eating themselves up, but I've learned long ago not to expect big and obvious noises to equal a big and obvious problem.

This said, I lifted the back end off the ground and found both wheels difficult to spin. They'd spin easily for part of a full revolution, then bind, then roll smoothly again. Then I started the engine and let it run off the ground:



While this looks like a brake pad dragging, it didn't explain the whining. Diff is full of fluid too.

I then pulled the axle shafts - left side, then right:

343m593.jpg


vdesgg.jpg


This is what I found, in order of discovery:

  • Left shaft wheel bearing spins fine.
  • With the left shaft out, the right wheel would spin and bind.
  • Right shaft wheel bearing spins fine.
  • With the right shaft out, the left wheel started binding through its entire run.

And here's where things got interesting: Even though the left wheel was still binding harder than I expected, the noise went away on the test drive I made immediately after reinstalling the axles. The feeling of friction holding back acceleration remained.

So before I make any assumptions here and re-adjust axle end play based entirely on the '68 shop manual, I wanted to run my theory by you fellows, to see if I'm barking up the right tree:

  1. I have a suspicion that the end play was set too tight, and the act of pulling and reinstalling the passenger's side axle allowed play to be introduced into the system; perhaps the retainer bent a fraction of an inch while being torqued down? Perhaps it's not really bottomed out and just feels it by bolt torque? Worthy theory, or hogwash?
  2. The last test ride still felt sluggish; as if something is dragging. Perhaps not only the end play is out, but the brake shoes are dragging as well. I'm pretty convinced of this myself, and it can't hurt to back down the adjusters all the way after I set the axle end play to disable the rear brakes for a test. Thoughts?
Thanks!

-Kurt
 
Glad to see this thread, I have kind of the same problem on a 8.75 with a sure grip. I just took her out on her maiden drive and I have the same sympyoms. Be interesting to hear what the experts here have to say about this. Thanks for asking.
Ed
 
Before you drive it more, remove driveshaft and axles and turn the pinion and see if the pumpkin turns freely, should only take around 15 inch pounds to turn.
 
Just FYI, it turned out to be nothing more than the left rear brake shoes dragging way too much. Pretty sure someone threw new pads on the car but didn't think to radius them to the drums, and the combination of surface mismatch and adjuster position made it chatter and cause the left axle to hang up and transfer the chattering to the side and pinon gears.

Drums might be the originals to the car too, but I didn't check to see if the radii matched on each; I'll probably be changing the drums anyway.

I also checked for pinion slack and rough meshing in the process; happy to report the third member had no grinding or excessive slack at all. Couldn't have been better had it been new; it spun beautifully the moment I took the drums off both sides.

For those who want to read the nitty gritty, I ran a similar thread at FBBO with a lot more commentary and details: 8-3/4 open diff whining, wheels binding, pulled axle shafts, problem...disappears?

-Kurt
 
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