Body lift

[Megamus]

Looking for a bit more room to fit my 35s however no 2 inch kits come with grade 8 bolts. Is it safe to use the grade 5 ones?

[YZEATER]

you can always buy them separate.

[Megamus]

ya i know that, but id rather not if the grade 5 will hold up. I figured grade 8 would be a good idea

[YZEATER]

they would probably be fine, but i always use grade 8 on everything.

[mithuth]

Have you considered high lining the hood/fenders and raising the rear flares and trim underneath them? It's free and you keep your center of gravity low...

I'm not a fan of body lifts.

The grade 5 should hold up fine unless you plan to extract someone/yourself using something other than frame tied in pull points. I doubt you're going to hit anything so extreme the body will fly off. Then again ... ok get the grade8 you never know. LOL

[Megamus]

Yea i have seen that done however i dont think i want to do that. The yj isnt lifted high anyway so a bl wont cause too much of a COG change

[Krod]

The bolts themselves are not your failure point. The body should tear at the mount before even a grade 5 bolt fails.

A properly rated (read: not import junk) grade 5 is sufficient. Corrosion is a common cause of failure in all fasteners , so a coated fastener can help prolong its life, especially under a jeep.

[tjblair]

Grade five is what you want anyway. They will streach a little bit instead of snapping. grade 8 would be too hard and can snap.grade 8's have there applications body bolts is not one of them IMO. Warn uses grade five to hold the winch to the plate.

[YZEATER]

Grade five is what you want anyway. They will streach a little bit instead of snapping. grade 8 would be too hard and can snap.grade 8's have there applications body bolts is not one of them IMO. Warn uses grade five to hold the winch to the plate.

high jack.

grade 8 is stronger in every way over grade 5. grade 5 will bend and break before grade 8 starts bending, or even breaking. it may break instead of bending first, but it will do so at a higher weight load then grade 5.

[tjblair]

My understanding is that a grade 8 has a higher clamping (or pulling )strenth, but a lower tensil strenth. in any matter grade 5 is what I would use on body bolts.

[Krod]

high jack.

grade 8 is stronger in every way over grade 5. grade 5 will bend and break before grade 8 starts bending, or even breaking. it may break instead of bending first, but it will do so at a higher weight load then grade 5.

BINGO.

Grade 8 is not "brittle" by any definition I'm familiar with. They are HARDER than a grade 5, typically around Rockwell C30 for grade 5.... C35 for grade 8. The extra hardness in a grade 8 gives it the "strength" that most people are after, which is really defined as material "toughness". Bottom line is the bolted connection is only as strong as the joint design and surrounding material. Check that area out before worrying so much about using grade 5 fasteners in a multi-point body mounting array. You'll be fine.

[tjblair]

I stand corrected:icon_hang: . here is the chart to prove yz and krod right.
http://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx

[Krod]

My understanding is that a grade 8 has a higher clamping (or pulling )strenth, but a lower tensil strenth. in any matter grade 5 is what I would use on body bolts.

I'm not sure I follow all of the terminology you used to describe it, but I think I get the jist of what you're saying your thoughts are....

Maximum clamping strength is directly related to ultimate tensile (UTS), and Yield strength, the maximum amount of tension a fastener or part can endure without permanently deforming.

Grade 5 is around 120 ksi (ksi= thousand PSI...NOT pounds) UTS
Grade 8 will be 150 ksi UTS

remember that the rating is in ksi or psi. That means you can't simply take that number as the amount of load a fastener can take. You need to multiply that number by area of the minor diameter of the fastener (fastener's smallest tensile area).

[tjblair]

I was thinking that if the force on the bolt was like if you were snapping a pencil that the grade five would only deform, where an 8 would snap. and with a body bolt espiceally one going through a body lift block this would be the case. but I guess the chart I posted proves me wrong.

[Krod]

I was thinking that if the force on the bolt was like if you were snapping a pencil that the grade five would only deform, where an 8 would snap. and with a body bolt espiceally one going through a body lift block this would be the case. but I guess the chart I posted proves me wrong.

They are both considered a ductile material, all common fasteners are. Meaning they will bend and deform before they 'snap'. The loading you're describing there is failure in shear (like breaking a pencil karate chop-style). That opens up a whole 'nother can of worms, but grade 8 is still stronger. Both can 'snap', and both can deform. The grade 5 will just deform long before the grade 8 does, and usually by that time the loading is so far along that the grade 8 fastener typically fails completely, where a similarly loaded grade 5 may have just bent and allowed the load to be released. Both are failures.

[tjblair]

Understood. I can agree with that.

[Super Scout]

Really I would think the body mount its self would rip apart long before the fastner broke...

[village_idiot]

Really I would think the body mount its self would rip apart long before the fastner broke...
it would have to. the body mount is 3/16" at the most, so it would rip before the bolts would have a chance to even bend.