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Removing Crossmember - Parts List Help for Broken Bolts

J

Jonner

NAXJA Forum User
Location
Charlotte, NC
So I have almost no experience drilling out/tapping rusty bolts so I've been doing a lot of reading and making a mental parts list. I just need to know if I'm going in the right direction. This is my DD and more than one weekend's down time means I could lose my job or fail college. I'm fixing one small issue at a time so I don't leave myself FUBARed without a car.



Problem 1) Broken flush crossmember bolt (1)
  • A - Grind flat with Dremel.
  • B - Center punch
  • C - Anneal
    • Bought small torch (heat wrench)
    • Use cool smoky flame to soften bolt
    • Need to buy fire extinguisher
  • D - Drill
    • Bought a 1/2" HD Milwaukee drill
    • Need to buy quality metal drill bits
    • Need to buy 7/16" tap
    • Work in increasing sizes until I reach correct size bit
Question 1) Advice needed
  • A - I found this: http://www.boltdepot.com/fastener-information/US-Tap-Drill-Size.aspx
    • Will I need 7/16"-14 or 7/16"-20?
    • I'm assuming one is course and one if fine, and I'm guessing I just need the course tap.
  • B - Drill bits:
    • I need a left-handed drill bit correct?
    • I am looking for HSS drill bits correct?
    C - Bolts:
    • What size bolt am I looking for at the fastener shop? 2" long?
    • Grade 8 - flanged head correct?
98 Cherokee Sport 4.0L AW4 if it matters. Thanks all!
 
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As previously mentioned, the bolts are metric.

Also, you're over thinking this. Soak it with PB for a few days, then start moving up the ladder from easy to hard:

1. Standard bolt-out kit
2. Drill out majority of bolt and try to twist it out with pliers.
3. Drill hole oversize and tap it for a new bolt.

In the future, soak those kind of bolts for a good long while before you just go snapping them off. It's reasonable to snap off the thinner bolts on the shock mounts, fender flares, etc, but you should be trying heating and penetrating oil and succeeding on bolts the size of the x-member bolts.
 
heat it, soak it, clean it, put a nut over it and tack weld it from inside the nut to the remaining piece of the bolt and thread it out.
 
I appreciate the replies - all good advice for NOT snapping a bolt. I learned my lesson on the first bolt... rushed it and didn't allow any soaking time for the PBB.

I don't have a welder and snapped one bolt off. I plan on drilling and tapping to next biggest size for the one I broke. So do I need a 7/16"-14 or -20 tap?
 
First of all, you can run your jeep with 3 bolts in the crossmember for a few days (I know from experience). Just go REALLY, REALLY easy on the gas.

Soak the broken bolts in PB for a while, then drill a small hole, then heat for a while (I use MAPP gas), then use an easy-out while it's still hot (don't heat the easy-out though). You can buy an easy-out at sears or just about any other tool store. But they're REAL brittle so be careful with them, I use a wrench not a drill on them. Don't heat anything till red hot, that can damage the steel.

If that don't work, take a flat peice of 3/16" plate, about 6" wide 8" long, bend it to fit along the bottom of your crossmember along up the side of the frame rail. Drill and bolt it though the crossmember with two bolts as close to the frame as possible, and then two bolts though the frame rail. Aint pretty but for a stock jeep it would hold. Use a hole saw (~1", maybe 1 1/4") through the plate to clear the head on that one stock bolt still on that side.
 
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Tellya what -
Pick up some 7/16" bolts in the length you want. I run a 1" drop and I think I used 2" bolts. Whatever pitch they are, buy a tap with that pitch. Then, reading the packaging on your new tap, determine which size drill bit you need. Buy that drill bit.

Drill broken bolt / stud through, using cutting fluid & going slow. Tap, install bolt.
Use torch & / or P-blaster to *not* break other bolts & studs. Drill, tap, install.

I been there myself, so don't take this as an insult, but you are over thinking this. Time to sack up, pick a tactic & do it. You'll be glad you did!
 
Mine are soaked with a combination of motor oil and transmission fluid, with some northeastern rust and road grime for seasoning. I haven't broken one yet. Make yourself a 50/50 mix of acetone and ATF (any type works), apply with a brush every time you drive the jeep or twice a day for a while. On the day you choose to do the work, heat them with the torch till they're nice and hot, quench with pbblaster, heat again, quench again, repeat a few times, quench one last time and carefully unbolt them. The most important thing is to NOT apply any off axis torque, i.e. use an extension on your ratchet and make sure it is exactly parallel with the stud instead of angled. Once they turn about a half turn, spray pbblaster up underneath, tighten back down a quarter turn, then loosen carefully.

I believe they're M8x1.5, not sure on the thread pitch, jeeperjohn could also be correct.
 
Don't feel bad OP. I snapped one of the 4 bolts myself last weekend when swapping in a 242 transfer case. I need to get on replacing the bolt. I've been driving with 3 all week.
 
M10x1.5

If you need any more specifics, Google "crossmember bolt size site:naxja.org". Couple of thousand returns on that, should be covered in exquisite detail.
 
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i snapped one swapping my 242 for a 231 i drilled it out then drilled four 1/2 inch holes in the side of the frame and cut out a small square and put a grade 8 through bolt in.
 
How big of an idiot am I for not getting around to the crossmember bolt yet? I have all the tools to fix it, am going to go to Fastenal on Monday and pick up some high grade 7/16" bolts. Already bought a quality Milwaukee drill, some high speed titatium Craftsmen drill bits, and Craftsmen taps.


I don't do any offroading and drive like a Grandma in the Jeep, and it keep it otherwise maintained?
 
^ This. And use Metric taps and hardware; they'll be handy for later work since M10 and M12 hardware is common on the XJ, and you won't need as many wrenches when you're working on it.
 
I broke one of mine when I dropped the powertrain for a swap. I was in the process of drilling it to tap, but the shop owner fished a smaller bolt through an existing hole in the frame when I went to lunch. Took him about 5 minutes to do the repair that was taking me a few hours--I think he was trying to tell me something. I still need to drill and tap mine but I'm afraid of pushing the temporary bolt out
 
I've been soaking it periodically, but I ran out of PBB. Tomorrow I'll be soaking in PB blaster again, then smearing grease on it. We've been having a lot of rain and that's probably washing off all of my PB blaster. Hopefully the grease will help retain some PBB on the threads.

I'll be drilling and tapping this week so I'll let you know how it goes.
 
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