HELP!! Screwed up front axle hub bolts

:explosion does anyone have any idea what thread the three 12 point bolts are that holt the hub on. I screwed the head of them up pretty bad!!!!

bolts

13mm

The heads are 13 mm. I'm not sure what the threads are, but I would recommend against using anything but the proper bolts. Either go to a junkyard and hope some are hanging around there, or bite the bullet and get them from Jeep. I'm pretty sure they're high grade bolts, and they're also necked down in the area where they pass through the knuckle. If you use normal bolts, they're likely to seize in the holes and shear off when you try to remove them a few years down the road.

just for future reference the threads are 12x1.74 mm.
I got my hands on some class 10.9 bolts, which is equivilant to a sae grade 8. I used a crap load of never sieze on them. I had to get it fixed to get to work on monday, love the weeked mechanic b/s, anyway according to my buddy the mechanic they sould be ok . I am a machinist and have access to all kinds of nuts and bolts, although they are allen bolts I can get just about any size I need. I love my job. So I'll see what I can come up with at work if you all think they arn't strong enough, maybe make some and have them case hardened or something. tell my what you guys think.

M8-1.25. Match the "underhead" length, but I'm not sure if you'll need a "fully-threaded" version (regular screws that long will be threaded about one inch from the end.)

There's no reason I can think of why you can't use a regular hex head capscrew, or even a socket head (if you're feeling adventurous.) However, I would recommend the following:

1) Use Property Class 10.9 or better. You may have to look for these.
2) If you can't get a "flanged" head (head will have a large round flange under the wrenching surface. Like the ones you pulled out, but can be any style of wrenching head,) use a hardened washer. You can probably use a 5/16" hardened washer on an 8m/m screw - I haven't checked to be certain, but it should work.

If you use never-seez, remember to reduce wrench torque by half (37-38 pound-feet vice 75 pound-feet.) Treat this point as important.

well that should be 12x1.75 it's an 87 I think later models use smaller bolts, correct me if I'm wrog but the bolts I got are 12x1.75 worked perfectly torqued it to 40 lbs with never seez.

M12-1.75 is about a half-inch screw, are you sure? (I don't have the means to check at the moment.) Still, that seems awfully big.

M8 is closer to 5/16", and if you use a 13m/m socket to remove it, it's almost definitely an M8 screw. Even with the flanged heads, they still hold to standard for head size vice shank size, unless it's specified as a 'reduced head' or 'expanded head' (as I recall, neither would be needed for this application.)

yep it's a big mother. went to advance didn't have it so I went to the hardware store sure as s#@! 12-1.75 it's close to 7/16 .472" to be exact

I just snapped a hub bolt off, gotta take my hub to a machine shop. We tried to tap ourselves but it kept eating up the tap. Should be M12 1.75mm, that's what the bolts were.

5-90 said:

M12-1.75 is about a half-inch screw, are you sure? (I don't have the means to check at the moment.) Still, that seems awfully big.

M8 is closer to 5/16", and if you use a 13m/m socket to remove it, it's almost definitely an M8 screw. Even with the flanged heads, they still hold to standard for head size vice shank size, unless it's specified as a 'reduced head' or 'expanded head' (as I recall, neither would be needed for this application.)

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Yes, it is that big at the threads. The 12 point head is definitely reduced, as is the shank where it passes through the knuckle bore. This is not a standard bolt.

Matthew Currie said:

Yes, it is that big at the threads. The 12 point head is definitely reduced, as is the shank where it passes through the knuckle bore. This is not a standard bolt.

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Interesting. Must be a ChryCo thing - since RENIX XJ's got M8-1.25 there (about 60m/m long, I think.)