A K5 Cummins Conversion: The saga continues...

[MaxPF]

It started out so simple; one of the straps retaining my rear u-joint had light between the strap and the u-joint cap. I have been chasing an intermittent bump-induced driveshaft vibe for months now, so I figured I may as well check out/fix the strap to make sure the cap isn't walking around in the yoke. Easy job, which should have taken no more than 30 minutes.

You want to know how to make God laugh? Tell Him your plans

So I pull the bolts retaining the straps. Now, having had them on and off a few times, and using Loctite each time, means the threads were gummed up. No biggie, I had a 6mm tap hot and ready to go. Oops... turns out they are 8mm, not 6. And I don't have an 8mm tap (mental note: add 8mm tap to my next MSC order). Fortunately, I DO have a set of Snap-On thread chasers, so I'm still in business. I throw the straps and bolts in a paint mixing cup and add a little acetone to degrease and de-Loctite the parts, then I crawl under the truck with the thread chaser and a 1/4" drive ratchet. I get about half way in, and I can feel the thread chaser getting mired in the goo. I back it out, clean it off, and run it back in. It's still gooey, so I lean on it a bit. Did I mention I'm using a 1/4" drive ratchet? There's only so much torque a mere mortal can apply to a 1/4" drive ratchet, and it ain't much. One moment I'm removing Loctite goo, and the next moment the ratchet suddenly spins really easy. Didn't even make a sound, just twisted the shank of the Snap-On thread chaser clean off. Using a 1/4" drive ratchet. Did I mention that part? Now, I have seen my share of broken $#!t, so I noticed two things. Snap-On's Sooper-Dooper thread chasers are maybe grade 8. They felt more like grade 5 when it broke. They are definitely not any kind of tool steel. Second, the shank could have been much larger. It was only maybe 1/4" diameter or so.

So there I sat, junk in one hand and a broken thread chaser in the other. And, of course, the rest of the chaser stuck in the yoke, which is firmly bolted to the pinion in my rear axle. Swell. Imake a phone call to my buddy Todd, who just happens to own a machine shop, and after a bout of laughter on his end he says that there are no jobs set up on the manual mill. Cool beans, I'm in business! I figure I will pop the yoke off, drill out the busted thread chaser, and while I'm at it I will machine the yoke to use u-bolts instead of the crappy straps. I bust out the 1/2" drive impact and a suitable socket buzz the yoke nut off, and try to slide the yoke off the pinion. It doesn't budge. I get on it with a plastic-faced hammer and it still doesn't move. Interference-fit splines. Swell.

Not a problem, I figure. My rear axle happens to be an AAM 14BFF, which has a drop-out pinion support. I zap out the 6 bolts holding the pinion support, tap it with the plastic hammer, and it slides right out. I jump in a borrowed beater and make haste to the shop. Ended up having to use a press to get the yoke off the pinion. Oh yeah, this will be a ball of laughs to re-assemble. I put that out of my mind as I examine the off seal arrangement AAM uses on these later model axles. Apparently, they really, REALLY don't want them to leak. I press off the dust cap and something that looks like a thick speedi-sleeve with an integral outer seal so I can machine the yoke. A carbide drill bit made quick work out of the broken thread chaser, after which I drilled out the holes to .394" for the 3/8" u-bolts. Then another half-hour of machining with a .750" end mill and the yoke was ready to go.

Now comes the fun part. I go to put it back together only to find out that the outer pinion bearing doesn't want to slip over the pinion shaft. WTF?!?! I fuss with it some more, and bigger than $#!t I manage to pop the garter spring off the seal WTF, is Mercury in retrograde or something? Of course, there is no way to re-install the spring with the seal in place, so I say eff it and remove the seal. At least now I can remove the outer pinion bearing from the support assembly and see what the deal is. Simple answer: it is a light PRESS FIT onto the pinion shaft! By this time I am swearing a littany of curses at the engineer who took a perfectly good design (the original GM 14BFF) and decided to "improve" upon it.

Since I don't have a shop manual for this new "improved" 14b, experience tells me that I will have to heat the bearing to 250°F and slip it down until it seats against the crush sleeve, then install the new seal, then heat the yoke to 250°F and tap it in place against the bearing. Then I can install the new nut and set preload. Nice. Now all I need is a new seal, since I destroyed the old one removing it. At least they don't appear to be too expensive.