jtdesigns Posted December 10, 2007 Share Posted December 10, 2007 Redoing the front brakes today and rounded the 12pt bolt that holds the caliper on. Any advice on getting it off???? Vise grips just anit doing it. Think heat will do it? Another question... WTH size is the hex head on the caliper slide? It's not 1/4 and its not 5/16 Metric?????? Link to comment Share on other sites More sharing options...
1999MJ Posted December 10, 2007 Share Posted December 10, 2007 what year truck is this on? Link to comment Share on other sites More sharing options...
jtdesigns Posted December 10, 2007 Author Share Posted December 10, 2007 89 2wd eliminator Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 10, 2007 Share Posted December 10, 2007 Redoing the front brakes today and rounded the 12pt bolt that holds the caliper on. Any advice on getting it off???? Vise grips just anit doing it. Think heat will do it? Another question... WTH size is the hex head on the caliper slide? It's not 1/4 and its not 5/16 Metric?????? The calipers are mounted with two slide pins that are removed with a metric hex allen socket. Look inside the rubber donuts on the inside face of the caliper. Link to comment Share on other sites More sharing options...
jtdesigns Posted December 10, 2007 Author Share Posted December 10, 2007 Redoing the front brakes today and rounded the 12pt bolt that holds the caliper on. Any advice on getting it off???? Vise grips just anit doing it. Think heat will do it? Another question... WTH size is the hex head on the caliper slide? It's not 1/4 and its not 5/16 Metric?????? The calipers are mounted with two slide pins that are removed with a metric hex allen socket. Look inside the rubber donuts on the inside face of the caliper. I thought that MF'er was metric... I still have a striped bolt I can't get off.. Its the 12pt bolt that holds the caliper onto the knuckle. Link to comment Share on other sites More sharing options...
500 MJ Posted December 11, 2007 Share Posted December 11, 2007 Some have that stupid 12 pt. I hate it. What the other guys are referring to is the hex replacement that can be bought at Carquest. Its much nicer and I recommend you go get yourself a set for each side. If you have a welder handy, weld a little piece of cold rolled stock onto the head of the bolt and turn it off that way. IF that doesnt work. Craftsman makes a rounded off bolt extraction set that you tap on with a hammer and then put a 6 pt socket on to get it off. I had to go get a set for some lug nuts after a shop used a darn impact to reef them on. Ended up rounding if off when I tried to take it off. I'll never go back to a shop that puts my tires on that tight again. :mad: Link to comment Share on other sites More sharing options...
MJ20 Posted December 11, 2007 Share Posted December 11, 2007 Yea they’re metric. I just bought some. 36mm axle nut socket ½ drive. 13mm 12-point socket 3/8 drive 7mm hex 3/8 drive. Link to comment Share on other sites More sharing options...
jtdesigns Posted December 11, 2007 Author Share Posted December 11, 2007 Some have that stupid 12 pt. I hate it. What the other guys are referring to is the hex replacement that can be bought at Carquest. Its much nicer and I recommend you go get yourself a set for each side. If you have a welder handy, weld a little piece of cold rolled stock onto the head of the bolt and turn it off that way. IF that doesnt work. Craftsman makes a rounded off bolt extraction set that you tap on with a hammer and then put a 6 pt socket on to get it off. I had to go get a set for some lug nuts after a shop used a darn impact to reef them on. Ended up rounding if off when I tried to take it off. I'll never go back to a shop that puts my tires on that tight again. :mad: No easy trick huh... No welder, so I guess I'll have to go with the bolt extractor. How much was the hex bolts? You replace the 12pts with an allen bolt right? Link to comment Share on other sites More sharing options...
500 MJ Posted December 11, 2007 Share Posted December 11, 2007 No no, sorry if I confused ya. You replace the 12pt hunks o junk with the 6 pt bolts Carquest has. I had to do it in a pinch (our carquest is open later than our hardware store) so I went out there and low and behold they did have the two bolt "kit" for like $9. So I got em. If it were during the day I would have tried the hardware store first... The 5 pc bolt extractor kit is here: http://www.sears.com/shc/s/p_10153_12605_00952161000P I'd take one of the bolts if you have one in with you so you can buy the set that will fit it the best (they sell different sizes in the 5pc sets of them). Or you can go all out and buy the $60 full set of them. Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 11, 2007 Share Posted December 11, 2007 I do not understand what you guys are saying about the 12-pt bolts. I just looked in my parts manual. The 2WD caliper mounting bolts for 87-91 XJs/MJs are the same, p/n 34201506. 7 or 8 mm allen, don't remember, two per caliper. Pull these, remove caliper. I just finished some front brake work on my 91 2WD, and the mounting bolts were these metric allens, and they have been there since new. So what don't I get regarding the 12-point bolts you're referring to? :nuts: Link to comment Share on other sites More sharing options...
500 MJ Posted December 11, 2007 Share Posted December 11, 2007 I wish I had a pic of them handy... I know they were on my G/F's '90 XJ and I have seen them on another front axle out of a '90 MJ. On the axle in the front of my MJ I had the 6 pt bolts but mine came from a '92 in the JY and I don't know the past history of it. Trust us, they do exist and are a major PITA. Be glad you don't have them. :thumbsup: Link to comment Share on other sites More sharing options...
jtdesigns Posted December 11, 2007 Author Share Posted December 11, 2007 I do not understand what you guys are saying about the 12-pt bolts. I just looked in my parts manual. The 2WD caliper mounting bolts for 87-91 XJs/MJs are the same, p/n 34201506. 7 or 8 mm allen, don't remember, two per caliper. Pull these, remove caliper. I just finished some front brake work on my 91 2WD, and the mounting bolts were these metric allens, and they have been there since new. So what don't I get regarding the 12-point bolts you're referring to? :nuts: The 12pts are on the caliper bracket. You know the metric allen head bolts that your talking about screw into it. Then the 12pt bolts attach to that bracket to the knuckle. I'm going to try to heat the bracket and then put a piece of ice on the bolt to see if that will break it free. If that doesn't work I'm going to grind the head off and try to extract it. Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 11, 2007 Share Posted December 11, 2007 I wish I had a pic of them handy... I know they were on my G/F's '90 XJ and I have seen them on another front axle out of a '90 MJ. On the axle in the front of my MJ I had the 6 pt bolts but mine came from a '92 in the JY and I don't know the past history of it. Trust us, they do exist and are a major PITA. Be glad you don't have them. :thumbsup: I do trust y'all, just haven't seen them. :cheers: Went back to the parts manual - in 1992-1/2 models (whatever the flock that means) the bolt part number was changed, so I ASSuME this is when Chryco went to the 6-pt metric allen bolt. Same p/n for 2WD and 4WD caliper bolts too. Previously the 2WD and 4WD caliper mounting bolts carried different part numbers. So it's been a good day - learned something again. :D :D Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted December 11, 2007 Share Posted December 11, 2007 I do not understand what you guys are saying about the 12-pt bolts. I just looked in my parts manual. The 2WD caliper mounting bolts for 87-91 XJs/MJs are the same, p/n 34201506. 7 or 8 mm Allen, don't remember, two per caliper. Pull these, remove caliper. I just finished some front brake work on my 91 2WD, and the mounting bolts were these metric Allen's, and they have been there since new. So what don't I get regarding the 12-point bolts you're referring to? :nuts: The 12pts are on the caliper bracket. You know the metric Allen head bolts that your talking about screw into it. Then the 12pt bolts attach to that bracket to the knuckle. This bolt is not required to be removed to remove the caliper. Cannot find a pic just now, but as stated there are two 12pt bolts that hold the caliper bracket to the knuckle and THREE 12pt bolts that hold the Unit bearing to the knuckle. You don't need to take these off to get the calliper off. Here is the only pic I can find just now. It doesnt show the caliper, but you can clearly see two of the three bolts that hold on the Unit Bearing on. If you look close, thru the rust. The bolts that hold on the caliper mount are not in this pic. On the newer axles, this mount was eliminated and the knuckle was cast as a one piece unit. Also as stated there are two bolts with hex heads only there is no real head the bolt is the same diameter. The size is 6MM IIRC. You really should get yourself a Chilton's or Hayes manual. CW Link to comment Share on other sites More sharing options...
jtdesigns Posted December 11, 2007 Author Share Posted December 11, 2007 here lucky I had them right outside :D ... phone pic cause my DOG ate my digi cam....... :nuts: anyway..... this is what I'm workin with.... Image Not Found Those two holes is where it mounts to the knuckle Image Not Found Link to comment Share on other sites More sharing options...
jtdesigns Posted December 11, 2007 Author Share Posted December 11, 2007 Also as stated there are two bolts with hex heads only there is no real head the bolt is the same diameter. The size is 6MM IIRC. You really should get yourself a Chilton's or Hayes manual. CW No their not 6mm That was the largest mm allen I had. The Chilton didn't list a size. Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 11, 2007 Share Posted December 11, 2007 Also as stated there are two bolts with hex heads only there is no real head the bolt is the same diameter. The size is 6MM IIRC. Thanks CW. And these are the only bolts (actually it's called a slide pin in the FSM) you need to remove take off the caliper (after squeezing with a C-clamp). At least on my 91 2WD. This is why I was having a problem understanding the 12-point stuff. Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 11, 2007 Share Posted December 11, 2007 Also as stated there are two bolts with hex heads only there is no real head the bolt is the same diameter. The size is 6MM IIRC. You really should get yourself a Chilton's or Hayes manual. CW No their not 6mm That was the largest mm allen I had. The Chilton didn't list a size. Think they are 7 or 8mm............ Link to comment Share on other sites More sharing options...
jtdesigns Posted December 11, 2007 Author Share Posted December 11, 2007 Also as stated there are two bolts with hex heads only there is no real head the bolt is the same diameter. The size is 6MM IIRC. You really should get yourself a Chilton's or Hayes manual. CW No their not 6mm That was the largest mm allen I had. The Chilton didn't list a size. Think they are 7 or 8mm............ Yeah that why I took the 12pts off cause I couldn't find the right size allen. It has to be 7 or 8... Find out tomorrow I hope... Link to comment Share on other sites More sharing options...
TNT Posted December 11, 2007 Share Posted December 11, 2007 External torxs bolts. Fun, fun.... :cheers: Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 11, 2007 Share Posted December 11, 2007 Also as stated there are two bolts with hex heads only there is no real head the bolt is the same diameter. The size is 6MM IIRC. You really should get yourself a Chilton's or Hayes manual. CW No their not 6mm That was the largest mm allen I had. The Chilton didn't list a size. Think they are 7 or 8mm............ Yeah that why I took the 12pts off cause I couldn't find the right size allen. It has to be 7 or 8... Find out tomorrow I hope... Okay, understand now. Just crawled under - it's 7mm. Link to comment Share on other sites More sharing options...
jtdesigns Posted December 11, 2007 Author Share Posted December 11, 2007 Also as stated there are two bolts with hex heads only there is no real head the bolt is the same diameter. The size is 6MM IIRC. You really should get yourself a Chilton's or Hayes manual. CW No their not 6mm That was the largest mm allen I had. The Chilton didn't list a size. Think they are 7 or 8mm............ Yeah that why I took the 12pts off cause I couldn't find the right size allen. It has to be 7 or 8... Find out tomorrow I hope... Okay, understand now. Just crawled under - it's 7mm. right on.. 7 it is but still have to get that POS 12pt bolt off.......... :headpop: Link to comment Share on other sites More sharing options...
500 MJ Posted December 11, 2007 Share Posted December 11, 2007 :laughin: - good to hear we resolved the bolt ID problem tonight at least! Link to comment Share on other sites More sharing options...
TNT Posted December 11, 2007 Share Posted December 11, 2007 here lucky I had them right outside :D ... phone pic cause my DOG ate my digi cam....... :nuts: anyway..... this is what I'm workin with.... Image Not Found Those two holes is where it mounts to the knuckle Image Not Found The bolts in the picture are external Torx bolts, not 12 point.... You need an external Torxs socket. :D Link to comment Share on other sites More sharing options...
TNT Posted December 11, 2007 Share Posted December 11, 2007 You need a socket like this... :brows: I'm not sure what size.... :roll: Link to comment Share on other sites More sharing options...
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