Posted: 1/2/2014 5:12:02 PM EDT
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Does anyone in or near Jeff City have a torque wrench capable of 380 FT LBS that I could use for 5 minutes? Or if anyone knows of any business near Jeff City that installs truck trailer hitches?
My situation is I just got my hitch in the mail today. Got it all bolted up to my truck and thought my neighbor's torque wrench would work, but after reading the torque specs and seeing 380 FT LBS. I've been at a loss on how to get or find out how to get this done to spec, so I can actually tow something. Neighbor, a long time mechanic was boggled on why it needed to be torqued down so much. If you have a wrench I can use, let me know what drive it is, so I know what adapters I need to buy. I have the hex bit socket needed to tighten the bolt down. Thanks. |
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Sadly, I don't think they work like that. Quoted:
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I have one that goes up to 250 ft pounds. Do it once set to 250 and once at 130 and that should add up to 380, right? Sadly, I don't think they work like that. Always a fun one to try on new guys in the shop. In all seriousness, red locktite and then hit that sucker with a good 1/2" impact. |
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Since it is a hitch, the wrench will likely be moving parallel to the ground, correct? If so, get a 4 ft long cheater bar on it, and give it what you think is a decent push. (100 ls of force). 380 ftlbs is quite a bit, if you even get in the neighborhood I'm confident your joint will hold. 4ft and a good hard push will do it.
If, for instance, the bolt was oriented horizontally, then just divide the necessary torque by your weight, and then find a cheater bar of that length, and stand on the end. |
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That's what I was thinking. Big ass cheater and give it all you got. Quoted:
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380 ft lbs means tighten the ever living fuck out of it with a long ass cheater bar. Using a torque wrench there would honestly never cross my mind  That's what I was thinking. Big ass cheater and give it all you got. Not with my crappy back. I was in pain after just going to 200. |
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Not with my crappy back. I was in pain after just going to 200. Quoted:
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380 ft lbs means tighten the ever living fuck out of it with a long ass cheater bar. Using a torque wrench there would honestly never cross my mind That's what I was thinking. Big ass cheater and give it all you got. Not with my crappy back. I was in pain after just going to 200. You will need a cheater bar of some sort, 3ft breaker with about 2ft of pipe is your best option for that kind of torque, you should only use the wrench to check it not tighten it. I know that sounds dumb, but when I was a kid, I worked at Wabash national in Lafayette, IN and my job was putting on semi trailer tires all day, at 125lbs a piece, they have to be torqued at about 3times their weight when using 2peice wedge lugs. They taught us how easy it is to break a torque wrench using it to tighten. We finally went to 1in impacts and an air torque but the first summer they had just opened and we were still tooling, it was a rough one! |
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Not with my crappy back. I was in pain after just going to 200. Quoted:
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380 ft lbs means tighten the ever living fuck out of it with a long ass cheater bar. Using a torque wrench there would honestly never cross my mind That's what I was thinking. Big ass cheater and give it all you got. Not with my crappy back. I was in pain after just going to 200. That's why you use a cheater. |
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Stitch, Give the guys at 4 Wheel Part Plus a call. It's just on the west side of town and close to you if you cut through by county park. The owner is a friend of mine & they install all kinds of stuff like that. I would imagine if you have it installed & just want it tightened they could do that real quick. eta phone number - 761-4000 |
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Stitch, Give the guys at 4 Wheel Part Plus a call. It's just on the west side of town and close to you if you cut through by county park. The owner is a friend of mine & they install all kinds of stuff like that. I would imagine if you have it installed & just want it tightened they could do that real quick. eta phone number - 761-4000 Will try them. Has been a hectic day for me and have not had any free time yet.. Thanks. |
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If you were a bit closer to Waynesville I could hook you up. We've got a big 3/4" drive torque wrench at work that goes to 450 or 500 pounds. Heck my Snap-On 1/2" will do 250... Quoted:
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4 Wheel Parts Plus and Autozone are no gos. My search continues. If you were a bit closer to Waynesville I could hook you up. We've got a big 3/4" drive torque wrench at work that goes to 450 or 500 pounds. Heck my Snap-On 1/2" will do 250... I may have to take you up on that offer next week. Have been calling everyone around and no one has any that go that high. By chance do you have a 3/4 to 1/2 adapter? Or a 3/4 drive socket with a 1/2" hex tip on it? I only have a 1/2 drive socket with a 1/2 hex tip and would need to know if I need to find an adapter. |
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I may have to take you up on that offer next week. Have been calling everyone around and no one has any that go that high. By chance do you have a 3/4 to 1/2 adapter? Or a 3/4 drive socket with a 1/2" hex tip on it? I only have a 1/2 drive socket with a 1/2 hex tip and would need to know if I need to find an adapter. Quoted:
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4 Wheel Parts Plus and Autozone are no gos. My search continues. If you were a bit closer to Waynesville I could hook you up. We've got a big 3/4" drive torque wrench at work that goes to 450 or 500 pounds. Heck my Snap-On 1/2" will do 250... I may have to take you up on that offer next week. Have been calling everyone around and no one has any that go that high. By chance do you have a 3/4 to 1/2 adapter? Or a 3/4 drive socket with a 1/2" hex tip on it? I only have a 1/2 drive socket with a 1/2 hex tip and would need to know if I need to find an adapter. Come on down, just give me a heads-up of when. I have a 3/4" to 1/2" adapter (along with a large assortment of sockets). Not sure about the 1/2" hex...I should have one in the Allen bit set that we have. But if it's the 1/2" Allen that needs 380 ft lbs., there's no way my Allen socket will take that much torque... What brand of hitch is this thing? |
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Come on down, just give me a heads-up of when. I have a 3/4" to 1/2" adapter (along with a large assortment of sockets). Not sure about the 1/2" hex...I should have one in the Allen bit set that we have. But if it's the 1/2" Allen that needs 380 ft lbs., there's no way my Allen socket will take that much torque... What brand of hitch is this thing? Quoted:
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4 Wheel Parts Plus and Autozone are no gos. My search continues. If you were a bit closer to Waynesville I could hook you up. We've got a big 3/4" drive torque wrench at work that goes to 450 or 500 pounds. Heck my Snap-On 1/2" will do 250... I may have to take you up on that offer next week. Have been calling everyone around and no one has any that go that high. By chance do you have a 3/4 to 1/2 adapter? Or a 3/4 drive socket with a 1/2" hex tip on it? I only have a 1/2 drive socket with a 1/2 hex tip and would need to know if I need to find an adapter. Come on down, just give me a heads-up of when. I have a 3/4" to 1/2" adapter (along with a large assortment of sockets). Not sure about the 1/2" hex...I should have one in the Allen bit set that we have. But if it's the 1/2" Allen that needs 380 ft lbs., there's no way my Allen socket will take that much torque... What brand of hitch is this thing? PM me an address, phone number, and what days and time your available. I'll bring my hex socket with me then, as that's what needs to be at 380 FT LBS. I would just need to use your wrench, adapter, and a cheater bar if you got one. The hitch is a "Curt". Thanks for saving my bacon on this. 
Link to install sheet so you don't think I'm nuts 4. Torque all 3/4" hardware to 380 ft-lbs. |
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That's ridiculous, the bolt is loaded in shear. I'll bet the holes are so large the only way it can transfer load is through friction.
190 foot pounds will put about 40 ksi preload in the bolt. There are very few applications where I would ever run the torque up so high (380 foot pounds) in an airplane installation, that would be in a joint loaded primarily in tension and fatigue critical, and I would analyze hell out of it first. I wouldn't torque the half inch bolts to 110 foot pounds, either. I'd have to do some analysis, but I think those loads are too high for grade 8 bolts in both sizes. |
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Well, I finally got it done. Went to HOB to buy an extension for my trucks trailer connection. While there, I inquired about a torque wrench. No dice, but they asked if I tried Al Scheppers in town. Went over there, talked to a young man, and explained my situation. He was able to get the bolt torqued down for me and wouldn't even accept any money for the job.
Gascozark, thank you for offering to let me use your tools. If you're ever up this way. Let me know and I'll buy you a beer or 2. |
Well Stitches, I owe you a big apology. I had to run to town and I swung by work to grab that torque wrench. Well, low and behold, I must be going senile because it only goes to 300 ft lbs. The only explanation that I can come up with is that I guess I was thinking of the big 3/4" torque wrench at the last place that I worked. The dang thing is 3 ft long. Go figure...
Again, I apologize for getting your hopes up. Concerning the bolt strength issue in question, I initially had the same thoughts till I checked some online sources. Most sources that I could find allowed that much torque on a Grade 8, 3/4" fastener. My gut tells me that 380 ft lbs is too much, but the charts say otherwise. 
ETA - This is what I get for starting a reply, getting distracted, and finishing it over an hour later. Glad you got it fixed up Stitches.
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I bet! That must be a good socket! What brand is it? Quoted:
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It's all good. It worked out in the end. Im surprised my socket didn't snap when the guy wrenched on it.I bet! That must be a good socket! What brand is it? GearWrench hex tipped socket. Bought it in a set of 7 sockets from AutoZone. The only place I found with a 1/2 hex tip. |
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GearWrench hex tipped socket. Bought it in a set of 7 sockets from AutoZone. The only place I found with a 1/2 hex tip. Quoted:
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It's all good. It worked out in the end. Im surprised my socket didn't snap when the guy wrenched on it.I bet! That must be a good socket! What brand is it? GearWrench hex tipped socket. Bought it in a set of 7 sockets from AutoZone. The only place I found with a 1/2 hex tip. GearWrench makes pretty decent stuff. I didn't realize that they made sockets. I'll have to check that out. |
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GearWrench makes pretty decent stuff. I didn't realize that they made sockets. I'll have to check that out. 7 piece hex tip set from 5/16 to 3/4. Ran me about $35 for the set. There was only slight marring on the tip after it was used to torque the bolt and me knocking it out of the bolt with a hammer when I got home. |
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That chart ought to include a note that says something on the order of "torques up to XXX". Every joint should not be torqued to the same value, sometimes it's detrimental. Certainly true, especially if your joint is loaded in tension. Between your preload and load, you could yield the bolt. |
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Certainly true, especially if your joint is loaded in tension. Between your preload and load, you could yield the bolt. Quoted:
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That chart ought to include a note that says something on the order of "torques up to XXX". Every joint should not be torqued to the same value, sometimes it's detrimental. Certainly true, especially if your joint is loaded in tension. Between your preload and load, you could yield the bolt. I started to add some speculation about the stiffness of the load paths in that assembly and deleted them. Without dimensions and gauges of the detail parts it's not possible to know the load carried by each fastener, but I'd bet that 3/4 inch bolt is not in a stiff load path and the 1/2 inch bolts are carrying the far greater part of the towing load. The flat plate and threaded bushing for the 3/4 bolt add up to a soft joint. |
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That chart ought to include a note that says something on the order of "torques up to XXX". Every joint should not be torqued to the same value, sometimes it's detrimental. Absolutely correct. In the automotive realm (as with most others I suspect), written torque specifications would always be used if available. It's my understanding that the chart is merely a maximum tightening guide. That being said, typos and other mistakes of that sort happen. Use common sense; if something doesn't sound right, there's a chance it isn't. I've seen mistakes in the factory service manuals over the years. Well, back when there were paper manuals at the dealers... |
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I started to add some speculation about the stiffness of the load paths in that assembly and deleted them. Without dimensions and gauges of the detail parts it's not possible to know the load carried by each fastener, but I'd bet that 3/4 inch bolt is not in a stiff load path and the 1/2 inch bolts are carrying the far greater part of the towing load. The flat plate and threaded bushing for the 3/4 bolt add up to a soft joint. Quoted:
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That chart ought to include a note that says something on the order of "torques up to XXX". Every joint should not be torqued to the same value, sometimes it's detrimental. Certainly true, especially if your joint is loaded in tension. Between your preload and load, you could yield the bolt. I started to add some speculation about the stiffness of the load paths in that assembly and deleted them. Without dimensions and gauges of the detail parts it's not possible to know the load carried by each fastener, but I'd bet that 3/4 inch bolt is not in a stiff load path and the 1/2 inch bolts are carrying the far greater part of the towing load. The flat plate and threaded bushing for the 3/4 bolt add up to a soft joint. Here's a pic of the hitch: 
The silver bolt on top of the bumper is the 380 LB one and the bolts on the bottom are the ones at 110 LB. |
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I know, but your photo makes me wonder about the details of the bumer where the 3/4 inch bolt passes through.
There's also the matter of the tongue load, and without that bolt the 1/2 inch bolts would have to transfer enormous bending loads, plus the plates they pass through would get the hell bent out them. The 3/4 inch bolt causes the moment due to tongue load to transfer as a shear at the 1/2 inch bolts and a tension load at the 3/4 inch bolt, which then gets distributed to the bumper mounts. If the 3/4 inch bolt is bottomed in that spacer and is not in contact with the upper surface of the bumper, it needs a few washers under the head to get it into intimate contact with the bumper. If it's gapped, test me; install the draw bar in the receiver, then stand on the end. If that bolt moves up and down without contacting the bumper, then it's also not reacting the bending load you are applying. Have someone peek at the flange where the 1/2 bolts pass through to see if it can be see deflecting while you're on the draw bar. The large diameter washers are a good idea that will help reduce that deflection. |
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I know, but your photo makes me wonder about the details of the bumer where the 3/4 inch bolt passes through. There's also the matter of the tongue load, and without that bolt the 1/2 inch bolts would have to transfer enormous bending loads, plus the plates they pass through would get the hell bent out them. The 3/4 inch bolt causes the moment due to tongue load to transfer as a shear at the 1/2 inch bolts and a tension load at the 3/4 inch bolt, which then gets distributed to the bumper mounts. If the 3/4 inch bolt is bottomed in that spacer and is not in contact with the upper surface of the bumper, it needs a few washers under the head to get it into intimate contact with the bumper. If it's gapped, test me; install the draw bar in the receiver, then stand on the end. If that bolt moves up and down without contacting the bumper, then it's also not reacting the bending load you are applying. Have someone peek at the flange where the 1/2 bolts pass through to see if it can be see deflecting while you're on the draw bar. The large diameter washers are a good idea that will help reduce that deflection. There is a plastic cover over the whole bumper. Under that is is a metal plate or what ever with a hole through it.( factory 2500 tow capacity if I used a ball hitch in it. ) The bolt makes direct contact with that metal plate and is threaded directly into the hitch under the bumper. The bottom bolts go through the factory tow plate attached to the frame and use the factory holes you would attach the tow chains. EDIT: bar installed and went jumping on it. No movement at all. Even the full bumper hitch installs the same way with that 3/4" bolt. |
| Wow. I would have guessed 380lb/ft was a typo. I put a hitch on my FJC and followed the manufacturer's instructions. The instructions specified something like 80 lb/ft and I snapped a bolt before I got to 60. Had to EZ-out the thing out and buy another bolt. Big difference between a 13mm 8.8 metric (Grade 5 equivalent) and a 3/4" Grade 8 though. |
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The 3/4 inch bolt serves the same purpose in that installation, although the pairs of bolts in the brackets can react the moment, the moment arm is much longer so the shears are very high. The 3/4 inch bolt is a good idea, I just have an issue with the installation torque. The project I work on has a couple of assemblies with torques higher than that and the USAF did not have one with enough capacity and a long enough handle at Whiteman so an airman could apply the torque, they had to get one from somewhere else. The rest of the assembly uses hydraulic assist to apply 70,000 foot pounds of torque on one part; I designed the tools for that job, and I'm pretty proud of the machine. It replaces one with a hand pump and nowhere enough capacity that was also dangerous to use. |
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The 3/4 inch bolt serves the same purpose in that installation, although the pairs of bolts in the brackets can react the moment, the moment arm is much longer so the shears are very high. The 3/4 inch bolt is a good idea, I just have an issue with the installation torque. The project I work on has a couple of assemblies with torques higher than that and the USAF did not have one with enough capacity and a long enough handle at Whiteman so an airman could apply the torque, they had to get one from somewhere else. The rest of the assembly uses hydraulic assist to apply 70,000 foot pounds of torque on one part; I designed the tools for that job, and I'm pretty proud of the machine. It replaces one with a hand pump and nowhere enough capacity that was also dangerous to use. With no directions, I would have applied red threadlocker and tightened to around 185 ft lbs.  A former student of mine's father is a mechanic on Sikorsky S-64 Skycranes. I remember them talking about the main rotor nut tightening to something like 40,000 ft lbs. They used some big torque multiplier hoisted up by a crane to tighten it. These huge torque values make me chuckle thinking about all the effort and equipment necessary to achieve them. Especially when I think about the meager torque values we use in the automotive industry.
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