Drilling/Tapping pinion yoke threads?

[SkylinePCG]

Not specifically related to the jeep, but theres guys here way smarter than me at this...

While trying to sort out a leaking pinion seal in the rear axle of a 97 Chevy truck, I broke 3 of the 4 u-joint strap bolts. Half of each of them are seized inside the pinion yoke. I tried an "easy-out" and broke a drill bit off inside one, and I was doubtful about that method to begin with.

Used ones arent removed from the axles (at least not around here), so none of the salvage yards around here have them.

Before I pony up $100 for a new yoke to finish off my $5 seal replacement, is it worthwhile drilling out the broken bolts, and then tapping new threads into the yoke? Or am I going to run into metal-strength issues trying to cut into the yoke and just waste more time?

For now the entire driveshaft is out, theres a "diaper" on the transmissions tailshaft, and a drain pan under the rear end. It looks pretty sad hobbling around in FWD.

[threepiece]

Fixturing the yoke on a machine that can hold the spindle on center of the broken bolts is the only way I would attempt such a repair. I think you will likely compromise the yoke by drilling out the bolt with a hand drill. Unfortunately, without the benefit of having free access to such a machine, the cost in having it done might come close to a new part.

I would not be comfortable adding much heat to a yoke until I was sure that it is not heat treated.

[FSJ-Earl]

I would drill them out and use U-bolts instead of the bolts and straps. I have done this to several rigs and have had no strength issues at all. I did this on my 94 XJ that is locked front and rear with 34 Swampers and I have twisted driveshafts and not broken a yoke or a u bolt.

[Carnuck]

What Earl said is the same as I've done.

[joe]

I think plan A was good but went off the rails trying to do it with a portable drill motor. The yoke needs to be mounted firmly and drilled out squarely with a drill press or milling machine. Takes a lot of experience to hand drill out a broken bolt by eye or you do exactly what you did...break the drill bit off or worse the EZOut. If you can still grab the stub of the bit and remove it you're still in the game to do Plan A correctly. If it's broken off flush, then that pooch has been screwed. There are shops in a lot cities that can electrically burn out the bolt/drill bit. Don't know what the process is called but it's doable if avail in your town. We had a rural welding shop that did it. Not inexpensive but for a rare or expensive piece worth it. Once the bolt is out have the holes drilled and tapped "correctly". Though used yokes may not be readily avail in NYC they are out there elsewhere. Sometimes ya just gotta admit to yourself: ok fair plan, bad execution that I wasn't able to pull off and just step back and punt. Yeah nobody wants to spend an extra $100 they didn't want to, but you reach a point where it becomes moot and ya just gotta get help and/or free up more bucks.

[SkylinePCG]

Well guys you're saying about what I was concerned with. In the grand scheme of things, $100 or so to keep a truck on the road is peanuts. She requires a little work once in a while but it's way less than a grand a year.

Regarding the u-bolt idea though, I always looked at the u-joint straps as an engineered "weak link." Reinforcing them I feel like would make the driveshaft a new weak link, and it'd be more $$ to fix, no?

[FSJ-Earl]

Depends what you are doing with your rig. I have drilled a dozen plus yokes, laying on my back or side under my jeep, replaced them with u-bolts and have never once had an issue with anything related to that quick, simple, easy, cheap mod / upgrade. Some people put to much thought into these things. You are only going up by a few 16ths of an inch so it is not like you are taking out a 1/2 inch of material.

[threepiece]

. The yoke needs to be mounted firmly and drilled out squarely with a drill press or milling machine.

Don't forget the lathe. There are at least three different ways I can think of to set up a yoke for drilling on a lathe.

[mokurt]

You will be better off buying a new U-Bolt yoke.

How was the seal surface on the old yoke,any grooves?

[SkylinePCG]

Yeah I ended up finding a new one on rock auto for $60. It's just a street driven commuter truck, and with over 255k miles on it, I don't have any reason not to replace it with stock stuff.

I think I could have made the old one work, and on the jeep I probably would have, but this one I just wanted the straightest line to getting back on the road.