Rear wheel bearing? - 99 Suburban C2500

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stutaeng

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92GMCK2500

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INSPECT the cross-shaft, C-clips, and axle shafts. Replace as needed.

My experience is that the axle shafts outlast the clips and cross-shaft; but check the axle shafts anyway. Most of the wear on the cross-shaft is from the spinning spider gears.

And if that doesn't fix it...I bet you need new clutches in the Gov-Lock.

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Poorly-posed; but the wear marks from the spinning spider gears on the bottom edge are visible...if you look hard enough. Wear marks from the axle shafts are very slight, nearly impossible to see in these two photos.
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Continued below.
Legend! Thanks again. Pictures tell a thousand words.
 

Pinger

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Here are the photos I meant to takes yesterday. The center block is actually not solid as I assumed...

I did find this source for axle endplay, but it's listed for the 14 bolt 9.5" GMT 800/900...
Thanks Shurkey - much appreciated.
I kinda figured there must be a block with the pinion cross shaft running through the middle of it.

I'm a fair way over the permitted 0.749mm axial play....

Couple of questions.
When there is more axial play than there should be, it isn't obvious whether the additional play is in the inward or outward direction - or both. For the C- clip to become dislodged, there has to be sufficient inward travel (as per the standard removal/refit method). Would the drum contacting the brake shoes' edges prevent that extremity of travel?

I'm still a bit freaked out that my G80 clutch packs could be at the root of this. If they are so worn as to be the cause, do you think the locking facility would still be functional?
 

Pinger

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The cross-shaft I pictured is from my G80 9.5" axle.

The "Gov-Lock" has several designs, the unit used in the 10.5" axle is substantially different than what's in the 9.5", which is different from the 8.5 Gov-Bomb.
I've been digging into G80s (including a how-to replace clutch packs on an 8.0'' unit) and am struggling to understand how correct meshing of the axle shaft gears with the spider gears is achieved and maintained.

I'm assuming that despite there being 'substantial differences with differently sized units, that the operating principle is the same across them all.
What I'm seeing when the locking is activated is the LHS (viewed from the rear) axle shaft gear being pushed rightwards and this motion is transmitted to the RHS axle shaft gear via the thrust block. Thus, the distance between the gears doesn't change - but that the two gears shift rightwards in relation to the spider gears (the hole in the thrust block being large enough or elongated to clear the cross pinion shaft). How does this not mess up the meshing? Or does the cross pinion shaft have enough play within the diff cage to allow for the motion? If so, is the force to move it in the direction of the axle shaft gears transmitted at the gears or, is the cross pinion shaft snugly fitted within the thrust block and moves in concert with it (but still within the constraint of its clearance in the diff carrier)?

How worn clutch pack(s) can affect axial play: only in the outward direction?
Inwards, the axle shafts are restrained by the cross pinion shaft - which can only move within its clearance in the diff cage.
Outward play is restrained by the C-clip acting against the axle shaft gear which in turn bears against the diff cage with the clutch pack between its and the diff cage's thrust faces. Thus wear at the clutch pack increases outward axial play.
Have I got that right?
 

df2x4

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Random thought... If the G80 carrier does end up being worn out, personally I wouldn't spend any time or money trying to rejuvenate it. IMO they weren't a great design to begin with. If one of mine ever fails I'm putting in a Detroit Locker or TrueTrac, unless I just end up swapping the entire 8.5" axle for a 9.5" semi-floater.
 
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