Rear Diff Thrust Washers...6 of them! (1 Viewer)

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Aug 22, 2014
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Stop me if you've heard this... RR brake job turns into bigger project. So, pulled the rear axles to replace the hub studs as they were too short. When I pulled the diff apart to get the C-clips out, I found not 2, not 4, but 6 conical thrust washers! 3 per side. Now, I know this ain't right as the worn gear surfaces tell me this. Here's the question... does anyone have experience with the spider gears wearing the diff case sooooo much over the 40 years that this much compensation is required? Or do I just have a shade tree disaster?!

And finally if the diff needs to be replaced (not the whole 3rd member, but just the open diff within it), can it be replaced without pulling the 3rd member out?

Advice welcome!
 
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Normally, spider gear backlash is corrected by adjusting the thickness of the side gear washers, not adding extra washers under the spider gears.

You can replace side and spider gears without disassembling the differential. Just remove the center pin.
 
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Normally, spider gear backlash is corrected by adjusting the thickness of the side gear washers, not adding extra washers under the spider gears.

You can replace side and spider gears without disassembling the differential. Just remove the center pin.


Thanks Pin_Head. I agree this is not the correct way to adjust! It seems like they might have been trying to bring the spiders down for better mesh with the side gears. So, that's why I was wondering if others had seen crazy wear between the spiders and the actual case. Seems wear this extreme calls for a new diff or complete 3rd. $$
 
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It is like pinhead said. I would pull the set of gears and look at the carrier for signs of excessive wear. If it doesn't look cracked or worn on spider gear surfaces just install a new complete set or a good used one. If it is worn you may want to upgrade at this point to a Detroit or ARB etc...
 
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IMG_0001.jpg


I'm no doctor, but this doesn't look so bueno.
 

pb4ugo

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I've not seen the kind of wear you describe w/the spiders & case, but I did run across a 3rd that had extreme wear between one side gear & diff the case. I had replaced a complete 3rd then slid in the axles and couldn't figure out why when I intsalled the brake drum, the brakes were dragging when the 40 was on the ground, the axle wobbled during inspection. The outer axle bearing had no play. I found the excessive play was between male portion of the side gear & the female portion of the carrier. I think I tried another side gear & found the case was worn. I plugged in another good 3rd & all was golden.
 
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So, is there a definitive post on what year rear differentials and/or 3rd members are compatible? SOR says 58-98 on the differential case, so I assume that's true... Anyone know about rear 3rd compatibility or anyone have one lying around?
 

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