64 Cheyenne Posted July 8, 2016 Share Posted July 8, 2016 I'm gettin ready to put a roll bar in the 87 utilizing the existing factory frame tie in brackets, my question is does anybody know the pitch and diameter of the bolts that go through the bar down into the bed mounts? I haven't found any metric ones that fit, seems that a 3/8 course thread will but I was under the assumption that nearly all the bolts on the MJ were metric and if they are, what pitch? BTW I looked and couldn't find the table I thought was posted, must be gettin younger, cause when I send a kid to find something..."I can't find it"..... Link to comment Share on other sites More sharing options...
DirtyComanche Posted July 8, 2016 Share Posted July 8, 2016 I don't know the answer, but a M10x1 is close to a 3/8-UNC. The M10x1 pitch is a bit different, but very close, and it's just slightly larger in diameter, thus typically you can easily thread a 3/8-UNC into a M10x1 nut/insert (but not normally the other way around). Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 8, 2016 Share Posted July 8, 2016 The factory p/n for those bolts is 34202158 if that helps. Link to comment Share on other sites More sharing options...
krustyballer16 Posted July 9, 2016 Share Posted July 9, 2016 I'm sure it doesn't matter... I made a set of those brackets for my "roll bar" then when I took the bed off I never put them back on. Just bolted to the bed mounts and thru the wheel well... The mounts aren't needed. If you roll it, that bar isn't gonna do much if it's mounted to the brackets or not. Link to comment Share on other sites More sharing options...
64 Cheyenne Posted July 9, 2016 Author Share Posted July 9, 2016 I'm sure it doesn't matter... I made a set of those brackets for my "roll bar" then when I took the bed off I never put them back on. Just bolted to the bed mounts and thru the wheel well... The mounts aren't needed. If you roll it, that bar isn't gonna do much if it's mounted to the brackets or not. "I'm sure it doesn't matter..." That sure is a lot of assumptions for somebody who hasn't even seen my truck in person, the bar I'm using etc. IMHO, any increase in the protection of the cab structure especially tied into the frame with the frame brackets is a good thing. The bar I'm using, I called it a "show bar" because I didn't want to open an engineering discussion about the bar...which is plenty stout as seen mocked up in my 87 build... http://comancheclub.com/forums/viewtopic.php?f=7&t=13953 "The mounts aren't needed. If you roll it, that bar isn't gonna do much if it's mounted to the brackets or not." Again you have not seen my bar or engineering... My opinion, bad advice, telling somebody "it don't matter", it's my life and whoever I'm with, there life matters. And "isn't gonna do much" well if I'm tumblin down a mountain, and we have big ones in Montana, I'd rather take what I can get as far as better cab protection for the occupants. Sorry my engineering is better than that.... Link to comment Share on other sites More sharing options...
64 Cheyenne Posted July 9, 2016 Author Share Posted July 9, 2016 Oh and the bolts were M10x1.5x50MM so they would go through the bar, adapter plate and rubber isolators. Link to comment Share on other sites More sharing options...
krustyballer16 Posted July 9, 2016 Share Posted July 9, 2016 I'm sure it doesn't matter... I made a set of those brackets for my "roll bar" then when I took the bed off I never put them back on. Just bolted to the bed mounts and thru the wheel well... The mounts aren't needed. If you roll it, that bar isn't gonna do much if it's mounted to the brackets or not. "I'm sure it doesn't matter..." That sure is a lot of assumptions for somebody who hasn't even seen my truck in person, the bar I'm using etc. IMHO, any increase in the protection of the cab structure especially tied into the frame with the frame brackets is a good thing. The bar I'm using, I called it a "show bar" because I didn't want to open an engineering discussion about the bar...which is plenty stout as seen mocked up in my 87 build... http://comancheclub.com/forums/viewtopic.php?f=7&t=13953 "The mounts aren't needed. If you roll it, that bar isn't gonna do much if it's mounted to the brackets or not." Again you have not seen my bar or engineering... My opinion, bad advice, telling somebody "it don't matter", it's my life and whoever I'm with, there life matters. And "isn't gonna do much" well if I'm tumblin down a mountain, and we have big ones in Montana, I'd rather take what I can get as far as better cab protection for the occupants. Sorry my engineering is better than that.... The "it doesn't matter" part was meant towards the metric/sae. Pretty much a "preference" kinda deal... same size so up to you thing. I used hardened bolts on mine.... And you're right, I have not seen your truck or bar. I read it as "factory roll bar". My bad. But even on an awesome condition mj,and I still don't know if yours is "built" or not, I think there are weaker points than the bed mounts that i/the factory be mounts are tied into. That's just my opinion. Mine is a daily driver so I don't worry about it rolling over and don't rely on the thin tube roll bar to keep the cab from crushing in. That is all I was trying to say.... Cuz I've built 2 sets of factory roll bar tie ins and know how and what they mount to. If not factory then I don't know on yours... That is all. Link to comment Share on other sites More sharing options...
64 Cheyenne Posted July 9, 2016 Author Share Posted July 9, 2016 I'm sure it doesn't matter... I made a set of those brackets for my "roll bar" then when I took the bed off I never put them back on. Just bolted to the bed mounts and thru the wheel well... The mounts aren't needed. If you roll it, that bar isn't gonna do much if it's mounted to the brackets or not. "I'm sure it doesn't matter..." That sure is a lot of assumptions for somebody who hasn't even seen my truck in person, the bar I'm using etc. IMHO, any increase in the protection of the cab structure especially tied into the frame with the frame brackets is a good thing. The bar I'm using, I called it a "show bar" because I didn't want to open an engineering discussion about the bar...which is plenty stout as seen mocked up in my 87 build... http://comancheclub.com/forums/viewtopic.php?f=7&t=13953 "The mounts aren't needed. If you roll it, that bar isn't gonna do much if it's mounted to the brackets or not." Again you have not seen my bar or engineering... My opinion, bad advice, telling somebody "it don't matter", it's my life and whoever I'm with, there life matters. And "isn't gonna do much" well if I'm tumblin down a mountain, and we have big ones in Montana, I'd rather take what I can get as far as better cab protection for the occupants. Sorry my engineering is better than that.... The "it doesn't matter" part was meant towards the metric/sae. Pretty much a "preference" kinda deal... same size so up to you thing.I used hardened bolts on mine.... And you're right, I have not seen your truck or bar. I read it as "factory roll bar". My bad. But even on an awesome condition mj,and I still don't know if yours is "built" or not, I think there are weaker points than the bed mounts that i/the factory be mounts are tied into. That's just my opinion. Mine is a daily driver so I don't worry about it rolling over and don't rely on the thin tube roll bar to keep the cab from crushing in. That is all I was trying to say.... Cuz I've built 2 sets of factory roll bar tie ins and know how and what they mount to. If not factory then I don't know on yours... That is all. The metric/SAE part does matter, as DirtyComanche said a 3/8 is close... but the correct bolt is a METRIC M10, if I was to use the SAE bolt, then I just threw all my efforts down the drain and should just use a "show" bar, the 3/8 fits, but I'm pretty sure it would pull through if stressed. One a side note, I wonder how many people have some type of bar in there bed and consider it a roll bar, since they did what they thought was the best engineering to get it securely installed, supplies some kind of protection and is better than just cab alone.This comment does not apply to true "show bars" that come in a box and are bolted together for looks only. My bar I'm talkin about has 2, 3" hoops welded together and 2, 3" welded together kickers both sides, plenty strong, fronts tied to factory mounts, kickers through wheel wells with strongbacks behind the sheet metal. Link to comment Share on other sites More sharing options...
krustyballer16 Posted July 10, 2016 Share Posted July 10, 2016 I am so confused at this point... But a 3/8" bolt is 1/32 or about .75mm smaller than an m10 bolt. I doubt jeep even had that tight of tolerances to begin with. And I doubt the 3/8 would pull through the 10mm hole before something else failed... Pictures would maybe help Mr understand what you're trying to do here. And I have a rolled, 1/4", or 6mm, thick backing plate on the wheel well mounts for my "show" bar or light bar or whatever were calling the factory hoop thingy in the bed. Link to comment Share on other sites More sharing options...
64 Cheyenne Posted July 10, 2016 Author Share Posted July 10, 2016 Done deal, pics will follow in my updated build of the 88, coming soon. (Winch, bumper, bed bar, rock rails, seats, paint, and more...) And the 3/8 bolt vs using a M10 bolt, don't do it, the 3/8 is clearly smaller and would work, but the engineer in the back of my head says it is not correct and puts a weak spot in the system. Saying "it don't matter" to put an SAE in place of a metric especially in this application is in my opinion, bad advice. My whole point of this thread was the bolt size, I had 3/8" bolts but they felt sloppy, didn't have the correct metric bolts and was hoping for someone to give me the correct metric size. No sketchy "They'll work, and it don't matter" for me cause it does matter.... And thanks for the input, cause this is how I learned about my truck (by being wrong) Link to comment Share on other sites More sharing options...
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