Ford 8.8 Differential Woes

[rspears]

Through a random series of events I pulled my rear wheels on the old 1990 F150 work truck, expecting to find a blown wheel cylinder. Instead I found a badly leaking rear axle seal, then discovered the problem with the brake in a rusted through & blown hard line tucked into a hidden spot on the frame. So, a trip to NAPA for a couple of sections of brake line and a new seal, and after replacing the line I jumped into the seal replacement, which I expected to take about an hour, maybe two at at the outside since the rear end is an Ford 8.8 which has c-clip axles. It turned into a mess, and I've learned that it's not an uncommon mess but not many people seem to be aware of it, so I'll post the story.
To change the axle seal you just pull an axle, but on a c-clip that means pulling the rear cover to drain the gear lube, then partially removing the pinion shaft between the spider gears, which then allows the axle(s) to be pushed in far enough for the c-clip retainer to be removed. The pinion shaft is held in place by a lock bolt/pin that's torqued into the carrier.
I removed the lock bolt,

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but only the nominal 1/2" long threaded portion came out. Here's that piece, shown beside a new bolt for comparison.
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The pin portion remained in place, locking the pinion shaft in place which creates a real Catch 22. You simply cannot do ANYTHING to the axles/carrier/spiders/ring & pinion until that pin is out. Some research told me that while many people think that the locking bolt breaks during removal, and there are recommendations to slightly tighten the bolt before trying to remove it, supposedly to prevent breaking. The truth is that they break because of the cyclic movement of the pinion shaft during operation, continually stressing the pin against the fixed threads above, causing a stress failure at the last thread. One site stated that in their experience over 50% of the locking bolts removed are broken this way.

As seen in the pictures, this bolt is not in the best position for "traditional" methods of getting to the broken part - like using an angle attachment on a drill, removing the passenger side carrier bearing cap, and trying to drill into the pin portion without taking out the threads, ruining the whole carrier. After fighting this thing for several hours trying magnets (hoping the pin broke just below the last thread), a scribe (trying to rotate it out), and several whacks with a BFH I started looking for help. The best solution I found was an "Extraction Kit" put together by Nick Fabbri in Riverbank, CA, which had many positive comments.

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The key parts are a pair of 5/16" hex socket bolts which have been precision drilled through the center, forming guides for the drill. Next is a 5/32" bit 12" long, plus a square extractor and a traditional spiral extractor EZ Out. The instructions tell you to use the shortest bolt that bottoms out against the broken piece, to help hold it from rotating, finger tight. Then it's a matter of slowly drilling, without excessive pressure, and with frequent removal to flush chips. Note that the long bit makes it easy to access the bolt.

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With the Extraction Kit removal of the offending piece was literally a five minute job from threading in the guide bolt to having the pin portion, with about 3/4 of one thread at the top, in my hand. As suggested by the instructions, I tapped the square extractor into place, and then tried to rotate it out by hand. I resorted to a pair of pliers to provide a bit better grip, and felt it start moving. Then it was simply a matter of backing out the piece.

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For anyone with a good lathe, making the drill guide bolts would be a piece of cake, but without a lathe all but impossible. With a drill guide bolt one could source a long bit from a local tool supply and accomplish the job. For me, the broken bolt was discovered late on Thursday afternoon, and I was leaving for the Old Marais River Run in Ottawa Friday. I finally broke down and ordered the Extraction Kit around noon, it arrived by USPS Priority Mail Monday afternoon, and the problem was gone this morning. Cost me $44 for the kit, a new locking bolt, and the shipping. I'd do it again in a heartbeat!