[akxj01]

.....thanks

[dz1087]

Even the grade 8's stretch quite a bit after bolt down. I don't know if I would be willing to risk it as it is a vital part to the drive train. A shock bolt, I'd say ya try it, but if a leaf comes loose, you're looking at some craziness happening.

[XJLI]

i know plenty of people using the autozone grade 5 specials without issue.

[joeyschribar]

i wouldnt wheel with it, but after 3 hard years wheelin i found out that i was runnin grade 5 hardware on my leafs, and not 1 issue haha!

[1990JEEPXJ]

im pretty sure most all u-bolts that come with lifts and from the factory are grade-5

[voodo3184]

i hope there ok i just put 4 in mine a few days ago ....

[BrunoS]

stock bolts for automotive suspension parts/chassis etc/ is Grade 5. other "specialty" bolts like head bolts, are different altoghether.

anyways:

Grade 8, while having higher tensile strength....is more brittle.

grade 5 will bend before breaking.

grade 8 can snap as it won't bend much.

go with grade 5, you will be just fine. it's 3 lines on the head (and +2) to make grade 5. most bolts are marked in such fashion. metric bolts are a little different.

[EricsXJ]

Originally Posted by BrunoS

Grade 8, while having higher tensile strength....is more brittle.

... but still exceeds Grade 5 breaking point. Every time people say that, they make it sound as if Grade 8 is then weaker than Grade 5. Grade 5 will stretch, but it will stretch AND break before the Grade 8 breaks due to it being "brittle".

[badron]

(IMO) No mater what grade bolt you use. Recheck torque after pounding on her for a bit. (IMO) any high stress bolts should be rechecked after some use. Hard offing just loves to loosen bolts.
To that end, Have you checked your steering box bolts lately?

[EricsXJ]

I agree that the u-bolts really need to be retorqued after a few hundred miles or so. As mentioned above, it is because the bolts stretch.

[BrunoS]

hmm.

grade 5 bolts are standard by design for underbody/suspension parts.

always use threadlocker (blue) on any bolt subjected to vibration (bushing bolts, LCA bolts)

always use antiseize on any bolt that will corrode into place (shock bolts, especially upper rear bar-pin bolts) or high temp/aluminum service (oxygen sensor, spark plugs)

following that: the major reason most folks don't use grade 8 bolts is due to their expense, and hardness should you snap these puppies. a grade 5 bolt is a lot easier to extract/drill/cut than a grade 8 bolt.

a grade 8 bolt is harder than any surrounding material it threads into...so instead of a sheared bolt, you get a busted off piece of engine block with your grade 8 bolt sticking in the broken part. drill bits will wander off center in a broken grade 8 bolt...and go into softer material nearby. on a item that is pounded severly for years...the grade 8 bolt will work harden metal nearby, like unibody sheet metal that's spot welded on our xj "frames". to see how this works, grab a piece of copper soft pipe and bend it back and forth. nice and soft, easy to bend at first...until you work harden it, and it cracks on you. same principle.

look...any damm bolt will work...but 99% of us will never exceed bolt strength on a grade 5 bolt anyways...and when we do, anything bolted to it has alrady failed.

[MrBuick]

I agree grade 8's are a pain to drill out, certainly if they get heat treated.... like say, and exhaust stud in a manifold...