stutaeng
I'm Awesome
??? OP has a 9.5" axle...
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Yep, and...??? OP has a 9.5" axle...
... limited options being in the UK.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.
??? OP has a 9.5" axle...
... limited options being in the UK.
Availability - no 'treasure yards' packed with GMT400s here - unfortunately. However, pursuing parts via Eaton and/or checking if any officially imported vehicles had the same components is worth considering now you've mentioned it.Whoops! Not sure how I missed that...
Out of curiosity is it more of a price markup issue or just availability? I figured you could probably get Eaton carriers over there fairly easily. Shows what I know I guess...
While I appreciate the thanks...that wasn't me.Thanks Shurkey - much appreciated.
I kinda figured there must be a block with the pinion cross shaft running through the middle of it.
I wouldn't count on that. Too many folks have the axle shaft walk out of the axle tube to rely on the brakes to save the day.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 don't have enough experience to answer that, except to say that clutches that worn aren't doing things any good.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?
Axle shaft gears = side gears, splined to the axle shaftsI'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.
With new-ish (fairly tight) clutch packs on both sides, the overall movement wouldn't need to be very much. As the clutches wear, the movement of the ramps on the one side gear and the ramps on the mating piece would travel farther, increasing the separation between them. So some of the additional travel would be used to lock the left-side clutch pack, with the rest being used to lock the right-side clutch pack.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?
The cross-shaft should be a slip-fit in the case, but with no obvious "slop".Or does the cross pinion shaft have enough play within the diff cage to allow for the motion?
I have to think the thrust block has an oval or oversize hole that allows the block to move relative to the cross-shaft.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)?
Yes. Extra movement in the "inward" direction can only be due to wear on the inside tip of the axle shaft, or on the matching face of the cross-shaft. Those parts do wear...but not very much.How worn clutch pack(s) can affect axial play: only in the outward direction?
The clearance between the cross-shaft and the differential case is not enough to be concerned with. Might as well think of it as "zero". In reality, I suppose a slip-fit of about a thousandth of an inch.Inwards, the axle shafts are restrained by the cross pinion shaft - which can only move within its clearance in the diff cage.
Yup. On one side, there's the matching-ramp part that causes the clutches to apply, but if you just consider that as part of the "clutch pack" you're correct.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?
Far as I know, the 7.5" and 8.5" Gov-Bombs are marginal to begin with. So I would think twice before rebuilding one. I'm not saying that I absolutely wouldn't, especially if it were in a lighter vehicle. But if I didn't already have a rebuildable core, sure, I'd be looking for an aftermarket differential case.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.
Almost certainly "outward", but you'll find out when you open it up.Just trying to see if I can tell if it's shaft and C-clips or clutch packs causing the problem which I may be able to do if I've correctly figured how it all works and, can gauge if the extra play is in the inward or outward direction.
"Schurkey the shovel." Well, better than the usual "Schurkey the turkey".As ever, waiting for Schurkey's (Shurkey the shovel - digging me out of another hole) comments
I'd open it up to INSPECT the cross-shaft and C-clips, and the matching grooves in the axle shafts. Replace parts as needed. But other than that, I think your process is right on.Reluctant at this point to order clutch packs until I know absolutely they are required. I'll open it up to replace the shaft and C-clips and again if it needs clutch packs. Or that's where my thinking is at the moment.
Here are the photos I meant to take 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...
Seems to me that there's a "special" C-clamp looking tool, for Gov-Lock "bushings" or some such. The service manual would tell all.
It has been years since I had one apart other than for gears/bearings, so memory is a little fuzzy. aI do remember the governor shafts/bushings being a pain to remove, cue expletives. There is a special tool, but you can improvise.
Link to one of them? Can't find one specific to a 9.5'' one of appropriate age (1999).Past the governor, I sure don’t recall anything difficult. I just did a quick net search and there are a couple videos out there that can show you how it is done.
No worries!Thanks stutaeng - I mistakenly thanked Schurkey for this post.
Did you pull the pinion and side gears out of that unit with the ring gear still attached?
Do you know for sure that your Gov-Lock is actually working? Mine did, when I first installed it. In fact, it was really aggressive, causing a noticable lurch around corners when I had the throttle applied. After about a month, I had no indications that it still functioned. Changed fluid a couple of times to remove all the Amsoil (with included friction modifier) gear lube, and now it seems to work again...I think. It's no longer aggressive at all, but it does seem to engage--smoothly--on low-traction corners. (Makes for easy U-turns )
Will stick with that terminology - ie, side gears and pinion gears.Axle shaft gears = side gears, splined to the axle shafts
Spider gears = pinion gears
See below.It'd be nice to find that you've got a couple of worn C-clips, and not have to dig into the clutches at all.
I'd open it up to INSPECT the cross-shaft and C-clips, and the matching grooves in the axle shafts. Replace parts as needed. But other than that, I think your process is right on.