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1tonMJ

Brake caliper bolt size

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I need to know the size of the bolts that hold the brake calipers on the front axle. I tried all the allen keys I have, and none work. I need to know so I can go to the auto store at crack @$$ in the morning. Thanks!

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I need to know the size of the bolts that hold the brake calipers on the front axle. I tried all the allen keys I have, and none work. I need to know so I can go to the auto store at crack @$$ in the morning. Thanks!

 

The brake caliper bolts should be 7 MM. That's what size they are on my 1986 Comanche. I hope this info helps.

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Would be nice if you let us know the model, year, etc. of your application 1tonMJ and what you are trying to do. Varies throughout the years. :dunno: :nuts:

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well I went to Autozone and got a 7mm hex socket, but it isn't fitting. The socket feels like it is just rounding out the bolt. Wrst case scenario, what do I do to just get the bolt out? Am I able to cut them, and remove the caliper that way? I know i would need new bolts after that. I don't know how to go about this. Any thoughts? Could I need a 6mm hex socket?

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I'm thinking it's an SAE size. Get a complete set of L-shaped allen wrenches. Don't cost that much. Or you can get a cheap set of allen sockets at Harbor Freight.

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It SHOULD be a 7mm Allen, but if someone tried to use a 6mm on it, they may have rounded it out. The newer ones (91+?) are a regular 10mm hex bolt, but they also used cast on caliper brackets and different brakes.

 

Maybe get an E12 socket and take the entire bracket off the steering knuckle, with the caliper still attached?

 

And watch out when buying a set of Allen wrenches, as most sets jump from 6mm to 8mm.

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94 D30 on one MJ has a 12mm hex head

93 D30 on the other MJ has, I believe, a 12 mm hex head.

88 XJ has 7mm female allen head.

99 XJ has a 13 mm hex head.

 

They never could make up their minds.

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94 D30 on one MJ has a 12mm hex head

93 D30 on the other MJ has, I believe, a 12 mm hex head.

88 XJ has 7mm female allen head.

99 XJ has a 13 mm hex head.

 

They never could make up their minds.

 

My 91 2WD also has the 7mm female allen caliper slide pins. The 88 4WD/2WD caliper bolts are the same. Then after 89, the slide pins were different between 2WD and 4WD too. Cornfused yet? :D

 

68132-md.jpg

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I don't remember what the 2wd beams on the MJs had originally, but the allen bolts sounds right.

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94 D30 on one MJ has a 12mm hex head

93 D30 on the other MJ has, I believe, a 12 mm hex head.

88 XJ has 7mm female allen head.

99 XJ has a 13 mm hex head.

 

They never could make up their minds.

 

Very.

 

I bought a full set of Allen keys, standard. Don't fit. Going back to buy the other sizes. Do they make these bolts with a regular head on them? I hate these kind. But what if the teeth are ground down? How do I get them out? New calipers are $20 apiece, I am going to spring for those. But what to do about the damn bolts?

 

edit: I looked at the metric Allen wrenches and they pack did not include a 7MM. So I bout a T-45 and a T-47 torx, I thought that might work. They didn't. From what I can see, if I use a saw to cut the bolts, and remove the studs, the new calipers will bolt right on.

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Very.

 

I bought a full set of Allen keys, standard. Don't fit. Going back to buy the other sizes. Do they make these bolts with a regular head on them? I hate these kind. But what if the teeth are ground down? How do I get them out? New calipers are $20 apiece, I am going to spring for those. But what to do about the damn bolts?

 

Nope, 89 and below are metric allen heads. These are hardened steel and are very difficult to "round out". The Allen wrench will round first. Get the correct 7mm allen (I use 3/8" drive sockets), tap it in the hole, and it should come loose.

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Since I've yet to get allen sockets, I would usually stick the 7mm allen wrench through my 7mm ratcheting wrench, and that would do the trick.

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I know its hard to see whats happening, but I'll bet that there is some junk in the hole stopping the tool from entering far enough not to round out. Clean out the hole, get a correctly sized tool and "persuade it all the way in. Even if you need to sacrifice it and buy new pins. It will be worth it.

 

CW

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Answered in your other thread... I agree with these guys 7mm is it. I had to tap mine in with the ratchet as they were full of gunk.

 

If they're really stuck and you are replacing the calipers and slides anyways, push the rubber dust boot back a bit and clamp a pair of vice grips on as tight as it'll go, that worked for me on one of the bolts.

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it is 7MM, but do not buy a 7mm adapter from walmart(stanley in particular), they will break off before turning that pin, i did it twice because i thought maybe the first time i was just being a meat hand. Also be sure if you buy an allen key ring to make sure it has the right size, the one that was hanging out in my garage only went to 6mm which was frustrating. Go to auto zone if your pins are real stuck and by a good 4-5 dollar adapter thats well made

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