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Thread: Jeep JK Wrangler Grade 8 Replacement Bolts - Do I Really Need Them?

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  1. #1
    Administrator wayoflife's Avatar
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    Exclamation Jeep JK Wrangler Grade 8 Replacement Bolts - Do I Really Need Them?

    I know there are a lot of people on the internet who really sound like they know what they're talking about and will tell you that you need to replace your factory 10.9 metric track bar bolt with a new 9/16" grade 8 shouldered one. And, I know there are even a few reputable vendors out there who sell whole grade 8 replacement bolts kits as if there's something wrong with all your factory bolts, BUT, I'm hear to tell you to NOT buy into the stupidness and save your money. Just because it's said on the internet doesn't make it true and let's face it, vendors are in the business of making a buck - they will sell you whatever it is you are willing to buy. Fact of the matter is, there nothing wrong with your factory bolts, they are the right size, they don't need to be shouldered and Chrysler purposefully put them on your Jeep for a reason.

    To put things into perspective, you need to know that there are over 1,000,000 Jeep JK Wranglers out there on the roads today and 99% of them or more are still running these so called "wrong size bolts", for about the last 8 years now and without ANY issues. If all these bolts are really the wrong size, you would think it would be all over the news and some kind of recall issued by now. What the naysayers don't understand is that if bolt size were really the only thing that mattered in keeping things from moving around, there would be no need for torque settings.

    Still not convinced? Let's take a closer look at how things work. When you look at the bushing of your track bar or control arms, the metal piece in the middle where your bolt will go through is called a "crush sleeve". AS IN, it's designed to get pushed really really hard from either end. The purpose of your bolts and nuts is to provide "compression" and cause your mounts to act like a vice by clamping down really really hard on the crush sleeve. The crush sleeves is NOT supposed to rotate AT ALL when installed correctly but rather, the bonded rubber bushing will twist around it. Of course, if you have a polyurethane bushing, heim or other aftermarket joint, the bushing will rotate around the sleeve or misalignment spacers - again, there is NO movement around the bolt and therefore, shouldered bolts are NOT necessary. This is the reason why bolts are rated for "torque" and NOT "sheer" - the value of compression strength is all that is necessary to hold things together. Don't believe me? Place a pencil between your index finger and thumb and hold it in the air. Why doesn't the pencil fall? I mean, there's no bolt going though your finger and thumb to hold it in place. Pinch it harder and it will even take effort to move the pencil around. Imagine that - compression alone made that possible.

    If you really want to spend money on your Jeep, invest in a good torque wrench and use it as a part of regular maintenance.

  2. #2
    Hooked Big b's Avatar
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    I don't normally post because I feel like I have a hard time putting my thoughts down. I also do not have near the offroad experience as a lot of people on here. What I do have is a background in automotive mechanics and engineering and now work in the natural gas industry which puts a lot of emphasis on fastener safety (I have been to week long courses about proper nut and bolt usage). With what little knowledge I have on the subject I can assure you that Jeep engineers put more thought into using non shouldered bolts into these bushings locations than any home mechanic ever will. A bolt is a "spring" and once torqued to it's design point or stretched it wants to relax back to it's original length, fastening the joint. To get the proper spring tension a lot of engineering goes into bolt design, I'm not sure but believe this is why full threaded bolts are used in these situations. When you use very high grade bots in shorter lengths it's actually harder to get the needed stretch or tension applied. For this reason in the Natural gas industry when fastening down high pressure pipe, vessels, or machinery we don't use the largest diameter, shortest, and highest grade bolt, but instead use several smaller diameter, longer, and the correct grade to give us the most clamping tension. Eddie is 100% right in the fact that the bolt is not designed for sheer, they are not axles and are not the parts that were engineered to accept the side load. The side load is handled by the sleeve and bushing, and is only fastened in place by a properly torqued bolt. When you decide to use shoulder bolts (especially high grade) you are bringing in some unknowns that weren't engineered into the system. These may in fact require a lot more torque to hold tension and not loosen, This could damage the crush sleeve, bushing, heim joint, or whatever else was not designed to be crushed as hard. I'm not saying that these grade 8 "upgrade" bolt kits do not work and solve some peoples issues. More than likely you are just masking the fact of improper torque. I just believe those issues could be solved with the factory bolts, proper torque, and maintenance. A better purchase would be a quality torque wrench.

  3. #3
    Old Timer GCM 2's Avatar
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    Quote Originally Posted by Big b View Post
    I don't normally post because I feel like I have a hard time putting my thoughts down. I also do not have near the offroad experience as a lot of people on here. What I do have is a background in automotive mechanics and engineering and now work in the natural gas industry which puts a lot of emphasis on fastener safety (I have been to week long courses about proper nut and bolt usage). With what little knowledge I have on the subject I can assure you that Jeep engineers put more thought into using non shouldered bolts into these bushings locations than any home mechanic ever will. A bolt is a "spring" and once torqued to it's design point or stretched it wants to relax back to it's original length, fastening the joint. To get the proper spring tension a lot of engineering goes into bolt design, I'm not sure but believe this is why full threaded bolts are used in these situations. When you use very high grade bots in shorter lengths it's actually harder to get the needed stretch or tension applied. For this reason in the Natural gas industry when fastening down high pressure pipe, vessels, or machinery we don't use the largest diameter, shortest, and highest grade bolt, but instead use several smaller diameter, longer, and the correct grade to give us the most clamping tension. Eddie is 100% right in the fact that the bolt is not designed for sheer, they are not axles and are not the parts that were engineered to accept the side load. The side load is handled by the sleeve and bushing, and is only fastened in place by a properly torqued bolt. When you decide to use shoulder bolts (especially high grade) you are bringing in some unknowns that weren't engineered into the system. These may in fact require a lot more torque to hold tension and not loosen, This could damage the crush sleeve, bushing, heim joint, or whatever else was not designed to be crushed as hard. I'm not saying that these grade 8 "upgrade" bolt kits do not work and solve some peoples issues. More than likely you are just masking the fact of improper torque. I just believe those issues could be solved with the factory bolts, proper torque, and maintenance. A better purchase would be a quality torque wrench.

    Thank you Big b,

    Along with Eddie's earlier post, this is by far the best detailed explanation of "using a proper fastener" ever to grace the forum. If anyone disputes this well written, factual logic you should be kick in the genital region repeatedly for continuing to argue your ridiculous shade tree mechanic rhetoric.

    Please lock this thread Admin.
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  4. #4
    Administrator wayoflife's Avatar
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    Thank you Big b for your most insightful follow up to my post. It was so insightful that I felt that this whole discussion needed to be it's own thread so that others can benefit from it and save their money.

  5. #5
    Nothing but a Thing sean.m.adams33's Avatar
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    Good thing I read this right before I clicked buy on amazon prime! But seriously, thanks Eddie, I too have wondered about doing the bolt upgrade mod.

  6. #6
    Living the WAYALIFE MTG's Avatar
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    Quote Originally Posted by GCM 2 View Post
    Thank you Big b,

    Along with Eddie's earlier post, this is by far the best detailed explanation of "using a proper fastener" ever to grace the forum. If anyone disputes this well written, factual logic you should be kick in the genital region repeatedly for continuing to argue your ridiculous shade tree mechanic rhetoric.

    Please lock this thread Admin.
    Quote Originally Posted by wayoflife View Post
    Thank you Big b for your most insightful follow up to my post. It was so insightful that I felt that this whole discussion needed to be it's own thread so that others can benefit from it and save their money.
    Wait a minute….

    Wasn't there some guy or "man with a plan" that had this all figured out? Pretty sure he trailered his jeep to wherever he "wheeled hard" and then posted about it?

    Seriously though, I want to hear from the AEV fans who have replaced their factory bolts in light of their research…

    On the one hand they taught the advantage of having an AEV lift as being designed by "former" jeep engineers, yet would replace their factory bolts (also designed by jeep engineers) for some after market bolts promulgated by a few "for profit companies" and the aforementioned expert?

  7. #7
    Been Around the Block jedg's Avatar
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    Quote Originally Posted by Big b View Post
    I don't normally post because I feel like I have a hard time putting my thoughts down. I also do not have near the offroad experience as a lot of people on here. What I do have is a background in automotive mechanics and engineering and now work in the natural gas industry which puts a lot of emphasis on fastener safety (I have been to week long courses about proper nut and bolt usage). With what little knowledge I have on the subject I can assure you that Jeep engineers put more thought into using non shouldered bolts into these bushings locations than any home mechanic ever will. A bolt is a "spring" and once torqued to it's design point or stretched it wants to relax back to it's original length, fastening the joint. To get the proper spring tension a lot of engineering goes into bolt design, I'm not sure but believe this is why full threaded bolts are used in these situations. When you use very high grade bots in shorter lengths it's actually harder to get the needed stretch or tension applied. For this reason in the Natural gas industry when fastening down high pressure pipe, vessels, or machinery we don't use the largest diameter, shortest, and highest grade bolt, but instead use several smaller diameter, longer, and the correct grade to give us the most clamping tension. Eddie is 100% right in the fact that the bolt is not designed for sheer, they are not axles and are not the parts that were engineered to accept the side load. The side load is handled by the sleeve and bushing, and is only fastened in place by a properly torqued bolt. When you decide to use shoulder bolts (especially high grade) you are bringing in some unknowns that weren't engineered into the system. These may in fact require a lot more torque to hold tension and not loosen, This could damage the crush sleeve, bushing, heim joint, or whatever else was not designed to be crushed as hard. I'm not saying that these grade 8 "upgrade" bolt kits do not work and solve some peoples issues. More than likely you are just masking the fact of improper torque. I just believe those issues could be solved with the factory bolts, proper torque, and maintenance. A better purchase would be a quality torque wrench.
    Eh... I posted this in another thread.. it's more appropriate here.

    Not sure it's been brought up before... the difference between the two bolts (14mm and 9/16") is just 11/1000ths of an inch.

    FWIW, I have 78,000 on my stock bolts and no issues and won't switch as I see no reason to. BUT, I thought I would educate myself on the real differences between the two bolts.

    As for the difference between Grade 8 and Metric 10.9; I looked at SAE J429 and ISO 898.1 (2013 version). I think it's a wash and so I don't think the argument that the 9/16th bolt is 'better' holds water. If anything, if you're not careful and use the course thread 9/16 (12 threads per inch), you might exceed the torque capacity of the bolt you're using.

    I know one argument will be the shoulder present on the 9/16" bolt will make it stronger. Mechanically this is a wash as the threaded area portion will still be the weak point on the bolt. (per http://www.fastenal.com/content/docu...renceGuide.pdf).

    The next argument for the shouldered bolt is that the shoulder works as a pivot point for rotation. I will argue that if the bolt is properly torqued, this isn't rotated upon. Rather the bushing (that surrounds the bolt) is held in place and the joint rotates around that. This would especially be true with aftermarket joints??

    ISO 10.9
    Med Carbon Alloy Steel, quenched and tempered
    Tensile Strength - minimum 1040 mPa (150,000 psi)
    14mm (M14 x 2.00) has a torque load up to 160 ft lbs dry

    SAE Grade 8
    Med Carbon Alloy Steel, quenched and tempered
    Tensile Strength - 150,000 psi (1040 mPa)
    9/16" (with 12 threads per inch) has a torque load up to 135 ft lbs dry
    9/16" (with 18 threads per inch) has a torque load up to 150 ft lbs dry

    Also, both have the same proof load (working tensile strength) of 130,000 psi (900 mPa)

  8. #8
    Administrator wayoflife's Avatar
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    Great follow up and great info but I can guarantee you that there will still be plenty of people out there who will still feel the need to buy replacement bolts and just because there are morons on the internet that sound like they know what they're talking about and say that they are needed.

  9. #9
    Been Around the Block Charlie Mike's Avatar
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    But the Grade 8 bolts are a nice Gold color!
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  10. #10
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    Quote Originally Posted by Charlie Mike View Post
    But the Grade 8 bolts are a nice Gold color!
    Match metal cloak components win win

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