Anyone have a clue whats going on here. The yoke on this 8 3/4 rear (489 case) looks like it sticks out of the housing by a lot. Ive got two 742 chunks and the yokes on those sits nice and tight with the seal guard right at the front face of the case.

This one is out almost a 1/4”. The bearings and races are correct. The races are bottomed in their bores.

I even removed the pinion and rested the yoke on top of the outer pinion bearing with the bearing in its race and its the same as shown. The case doesnt look like its modified. I tried 3 yokes. All sat the same way. I got a new yoke. Still the same. Ive measured the yoke and it matches the others.

Surely this isnt right? Is it? Why does it sit so far out?

Sure throws up red flags to me.

The most chronic ailment that caused the 8 1/4 and the 9 1/4 failure was the pinion nut backing off. I don't know if it was caused by a failed crush sleeve, or a defective nut, pinion threads, or the pinion nut not quite torqued to specs (over tightened or under tightened). That 498 case has the crush sleeve that may be damaged.

With those, as the nut backed off, the pinion would slip back into the housing, and work its way back and forth until something bound up and failed. The first thing you noticed was when you shifted from a forward to reverse vehicle movement, or reverse to a forward vehicle movement, you could hear what sounded like a U joint going bad with an auditable clank. The clank was the pinion moving back and forth against the ring gear and the crush sleeve, but most people looked at the U joints, which were probably OK.

I'm suspecting that when you can see the gap between the yoke and the housing, you would find the pinion nut can be easily tightened with a wrench (at least the one's I've seen could be).The concern would be how much damage has been done by the pinion shifting back and forth ever time the vehicle is driven in the other direction.

Is this a newly set-up diff? If so, maybe the crush sleeve isn't "crushed" enough.

Soild spacer or crush sleeve ?

Did you make measurements of the 2 pinions to compare all dimensions of the pinion stem and determine that they are the same ?

So this is the original 489 case to my AAR. Is also the original pinion and the original ring gear and original sure grip. I put new bearings on the pinion used the samee washer behind the big pinion bearing. I used a crush sleeve eliminator with shims or more correctly shim with a new outer pinion bearing andnew races. I had the nut torqued down down to 120 which was low but surely wouldn’t pull that yolk in more than a smidge once at his final torque. I had pinion preload set to 20 inch pounds of preload.

I was getting ready to install it so I was going to takeoff the yoke one last time to put the seal in and then recheck everything but that’s when I noticed the difference between the 742 case and my 489 case

So I ended up taking it all apart, removing the pinion completely, and just putting the outer pinion bearing on its race just resting there and put the yoke on top of the bearing and it is still out that far. It can’t go in any further, not unless I can move that race in deeper in the case by another quarter inch but it’s up against the lip in the case.

I’ll snap some photos in a minute

Couple more things. This solid sleeve that I used in place of the collapsible spacer is pretty much, the exact same size lengthwise of the collapsed spacer I removed. I also measured the thickness of all the bearings and all the races and they match the original Timekin bearings that I removed. Bearing are the same brand. Made sure in usa.

So, here are some pictures I’ve taken it shows the races seated in the boar. I showed the bearing sitting in the outer race, and the distance between the top of the bearing and the thin washer to the top of the case is only .710 inches, whereas the yoke sealing surface measures approx 1”. The seal guard extends over that sealing surface but theres about .800” from the end of the yoke to the top out rim of the guard

More pics

So you can see from the pictures the races are seated. The pinion bearing is definitely seated up against the washer at the pinion gear. And the last two photos are just the yoke sitting on top of the bearing in that thin washer, and it’s still shows quite a bit of distance between the seal guard, and the top of the case I have no clue why it looks like this but all of my yolks, and I’ve got several all the same gap

If the solid spacer is the same height as the crushed crush sleeve adding a spacer is going to make it stick out further like that. I have always had to machine a little off the solid spacer to use one.

do you have another crush sleeve that is not crushed , if not you can use the sleeve you have with a shim from your solid spacer kit and retorque it with the spacer to the desired bearing preload. Once you have it reset to what it should be and the the yoke looks right you need to measure the solid spacer with the shim and shorten the solid spacer to that measurement.

does the yoke sit out like that with the original bearing ? did you take before disassembly pictures ?

how far down does it sit without that shim between it and the bearing ? You also don't have the seal it yet so your gap with be .060 smaller.

You said you were taking out 4.30 gears. Would the carrier be different for such a steep gear? If you used same carrier and it was slightly thicker to account for such a small pinion (the 4.30 ratio requires smaller pinion), a stock ratio would have the pinion now push out.

Just a thought.

None of the 8 3/4 rear ends with drag race gears in them, 4:56 and + needed or had spacers or any other mods to the stock posi units, Dana or Eaton corps, to work properly.
Dana 60 have two separate type and size posi carriers, the 3 series, fits from 3:54 to 4:30 after market gears. The stock Dana 4 series carriers fit the rest of their ration from 4:56 up to 6.87

It has been a longtime since I have set up a gear set in a 489 carrier but I'm going to say I have seen those oil slingers that far away from those cases
IHTHs

how thick is the washer/shim under the yoke? is it needed? does washer go under nut? wrong front bearing/race? match up with old

Umm...this may be a silly thing, but is there not a yoke snout seal that still needs to fit on there?

So I'm thinking the flange of that seal will probably take up 1/8", or thereabouts...in my case I have a '742 housing, with a billet yoke and absolutely no dushshield. What shows is about 1/4" clearance.

Otherwise, the depth of the nut on the pinion certainly shows that it can't "push" the yoke on any further, which means that if the crush sleeve solid spacer replacement is the same, the extra length must be coming from somewhere in the race & cup combinations.

Assumption here being: there is no clearance left between the pinion head and the bearing, meaning it is correctly and fully mounted.

The solid sleeve (used in place of the collapsable one) was shortened. It was too long as you said so the preload couldnt be obtained. I shortened the solid crush sleeve eliminator enough so I could use a shim from my pinion shim kit to get the right pinion preload.

I took the pinion back out today (thats how I got all those pics above. But even still, the yoke sticks up the same amount.

If you look at the pics above, you can see all of the races installed in the case, are completely seated up against their stops. So, even without the pinion in the third member, I took the third member with nothing but the two pinion races installed and placed the outer smaller, bearing in the outer race, and just laid the yoke on top of the bearing in the gap is the same. The yolk can’t go into the case any further, because the end of the yoke is resting on the pinion bearing that’s sitting in its race which cannot be moved deeper into the case to close the gap.

Heres that picture. Its the 489 case, pinion races installed and seated. Small out pinion bearing then the yoke. I just don’t see any way for that yolk to move into the case deeper because the bearing is what’s holding it up and the bearing can’t go into the race any further and the race can’t go into the Case any further because it’s up its stop.

I’ve tried using the original bearing that I removed, but not the original race but the race looks to be exactly the same sizeM

I’m thinking this is just the way it is. I can’t explain it

yes the yolk appeared to sit like that with the original bearing but I don’t have any pictures of it when I was taking it apart. I thought that maybe I had tried to remove the yoke previously and that’s why there was a gap there, but I didn’t think anything of it at the time until reassembly. The shim that I had mentioned is the shim that goes on top of the crush sleeve eliminator to set the preload. That shim is underneath the outer, bearing between the bearing and the sleeve eliminator. There’s also a thin washer that sits on top of the small pinion bearing on the big end that the end of the yolk sits on when it’s all assembled. And that washer is .020 or .030” thick. And it’s the stock piece that was on there before.

I’m not moving gears from one sure grip to another. I’m not moving a sugar grip from one case to another. I am just taking out a 742 third member with 430 gears in it and replacing it with the original third member 489 case with my 391s already installed on the original cone sure grip

So I had a third member that’s original to my car and a 489 case and all I did was change out the bearings for the pinion and the differential and replaced the crush sleeve with the sleeve eliminator (with a shim tor preload)

I didn’t measure the thickness of that washer that’s between the yolk and the smoke outer pinion bearing but it’s Maybe .020. And I don’t know if it’s needed but it was there originally, and it shown in the service manual is being there. I guess it’s only purpose is just to put something in between the end of the yolk and the bearing surface so even if I took it out, we’re not gonna See a quarter inch difference just gonna see the yoke .020” closer.