Author Topic: Axle U-Bolts (Read 4251 times)

BlackYJ · « **on:** December 23, 2006, 12:08:00 PM »

So I went down to Standens yesterday to get some new u-bolts for when I install my new springs and all they sell are grade 5 bolts. I am guessing this will be sufficient, but I remember some saying to only use grade 8 bolts. Now Standens is a pretty big suspension manufacturer so I trust them, but can anyone shed some light on this for me. I am pretty sure the u-bolts I install with my OME suspension where grade 8, but I believe those came from Rancho or something.

midnightcowboy · « **Reply #1 on:** December 23, 2006, 02:10:19 PM »

i try to use gr 8 on all suspension and steering parts. thats a personal thing though.

BlackYJ · « **Reply #2 on:** December 23, 2006, 02:54:36 PM »

The guy at Standens siad they don't even sell grade 8 bolts

calltrex · « **Reply #3 on:** December 23, 2006, 03:17:03 PM »

We deal with standens all the time. Never any problems with there stuff. Nothing i would be worried about.

If you can break there U Bolts your probably doing something you shouldnt have....

Dragonmaster · « **Reply #4 on:** December 23, 2006, 03:46:15 PM »

In most cases grade 5 is more than adequate (hence the reason you won't find ANY grade 8 bolts on most modern vehicles), grade 8 is a nice to have for serious abuse.

Brink · « **Reply #5 on:** December 23, 2006, 07:30:30 PM »

Grade 5 and 8 serve entirely different purposes truth be told.

Grade 5 is strong but still somewhat flexible. In some cases that is better because it will give instead of giving up.

EDIT-{the following is inaccurate-taken from years of being told it only to find out today it's not factual}
Grade 8 is stronger than grade 5 but in a shear load it can be brittle. They will break not bend. No chance to catch a failure before it happens on them. They are really great when thread tension is very important. There being no give in the threads keeps things tight. If there is load applied to the nut or head trying to pull the bolt apart they are much stronger. {end edit-sorry Eric}

Fact is that replacing a manufacturers recommended grade 5 bolt with a grade 8 is just a bad idea. They spec their stuff the way they do for a reason. Maybe if the bolt holds up because it is grade8 it will lead to a more substantial, costly, or dangerous failure elsewhere in the system.

So what's all this got to do with your u-bolts? Gotta be that grade 8 is either too brittle or just way overkill I guess. At any rate I really wouldn't be worried at all about trusting what Standens suggests.

As far as grade 8 on modern vehicles..... you don't find em because everything is metric now. The 10.xxx on many bolts on our jeeps is roughly equal to a grade 8. Trackbar bolt at the axle end is a good example.

Eric

BlackYJ · « **Reply #6 on:** December 24, 2006, 05:32:32 PM »

True enough, but the nice thing about grade 8s, is that their yield strength is higher than a grade 5s tensile strength, so a grade 5 will break before a grade 8 will even begin to yield.

I know it is not a high stress location since it is only tension, but I just wanted to make sure

Mudhawg · « **Reply #7 on:** December 24, 2006, 06:02:38 PM »

Scott mind if i ask how much ya paid? i need to get new u bolts for my Jimmy so i can put my lift in and just wonderin what kinda price range

BlackYJ · « **Reply #8 on:** December 24, 2006, 10:34:49 PM »

They were a little under $8 a piece for bolt, nut, and washer

Mudhawg · « **Reply #9 on:** December 24, 2006, 10:47:14 PM »

thats a pretty good price... i was expecting alot more

TrappersJeep · « **Reply #10 on:** December 25, 2006, 12:19:06 AM »

Here's some more info on the grade 5 vs. 8 debate - http://www.pretzlaff.com/NA4WDA/viewtopic.php?t=8[/url]

TheCustomizer · « **Reply #11 on:** December 25, 2006, 01:02:04 AM »

Quote from: "Brink"

Grade 5 and 8 serve entirely different perposes truth be told.

Grade 5 is strong but still somewhat flexable. In some cases that is better because it will give instead of giving up.

Grade 8 is stronger than grade 5 but in a shear load it can be brittle. They will break not bend. .

I'm sorry to rock the boat here, I realize this isn't 4wheeler, and not a "fight site" like AO lol, but this post couldn't be further from the truth, and somebodys gotta say something to correct this.

The fact is, Grade 8 bolts are designed to be more flexible than 5s, with a higher break point. Shear force will break a grade 5 before it bends, equivilent force will bend a grade 8 before it breaks. I have personally witnessed 3x3/8" grade 8s bend all the way around (no heat) until the tip touches the top (say that 5 times fast lol). Then the same 3x3/8" grade 5 *snap* under the pressure before it gets even near tip to top.

I'm a big fan of grade 8s, when you consider the cost difference, (pennies per bolt) why put something in your rig that "should stand up to the load" instead of something that will be ten times stronger than it ever has to be? All the work that gets done in my shop is done with grade 8s, whether its fan blade bolts on the truck I sponser, or bumper mounts on a ZJ, its all grade 8. Why squirt around for the sake of a couple bucks?

Quote from: "Brink"

No chance to catch a failure before it happens on them. They are really gread when thread tension is very important. There being no give in the threads keeps things tight. If there is load applied to the nut or head trying to pull the bolt apart they are much stronger..

Can you elaborate a bit on your point of view here Brink..... this dosn't make much sense to me.

Quote from: "Brink"

Fact is that replacing a manufacturers recomended grade 5 bolt with a grade 8 is just a bad idea. They spec their stuff the way they do for a reason. Maybe if the bolt holds up because it is grade8 it will lead to a more substantial, costly, or dangerous failure elsewhere in the system.

I gotta disagree here wholeheartedly. The bottom line..... on any rig build, whether it be a trail ridin jeep, rock crawlin jeep, a mud boggin chev or a racin chev, is make it as strong as physically possible, everywhere you can. Making 1 point weaker than another is just going to leave you stranded somewhere, gettin towed out, who cares if its a $100 part or a $200 part, busted is busted lol.

Quote from: "Brink"

They spec their stuff the way they do for a reason. .

Then why don't they "spec" 38s, lockers front and back, winch bumpers and smallblocks into stock jeeps? When we "build" a rig ...... we "BUILD" a rig....."build" means you make it capable.

Quote from: "Brink"

So what's all this got to do with your u-bolts? Gotta be that grade 8 is either too brittle or just way overkill I guess. At any rate I really wouldn't be worried at all about trusting what Standens sugests..

I agree with you about "wouldn't be worried at all about trusting what Standens sugests." , but grade 8s brittle ? You couldn't be farther from the truth. Compared to grade 5s, grade 8s might as well be made of lead lol.

Quote from: "Brink"

or just way overkill I guess...

Overkill is "the name of the game", 'cause busted rigs suck.

I don't mean to tear your post apart here, but you've given some bad advice in my opinion. Standens "suggestions" are based on the opinions of guys that deal with street vehicles day in and day out. Some of the guys in the shop are wheelers, and I'm sure some of them know their stuff, but the company on the whole is not a credible source of information for off-roaders. Why anybody would put grade 5 bolts into anything on their rig is beyond me, you might as well mount your cd player with 'em too.... for the extra $0.80 lol. My theory, is build it so it won't break if you drive it off a friggin cliff lol, especially when it comes to pocket change on bolts.

TheCustomizer · « **Reply #12 on:** December 25, 2006, 01:19:23 AM »

The comment on the link listed above, concerning "the weldabilty" of grade 8s is bullcrap lol. Grade 8s take a weld better than 5s, you have to know how to lay a proper weld to do it, grade 8s require a touch more heat than 5s. Some guy with a 110V flux core Mig is going to have a bitch of a time welding a grade 8 as oposed to a grade 5, he dosn't have the heat..... = some dude complaining about "the poor weldabilty of grade 8s"

Thatguy · « **Reply #13 on:** December 25, 2006, 01:32:37 PM »

Read billavistas book on fasteners for dummies................

http://www.pirate4x4.com/tech/billavista/NutsandBolts/Nuts&Bolts_signed.pdf

Bottom of PAGE 8...............Titled "What Grade".

answer is pretty clear

BlackYJ · « **Reply #14 on:** December 25, 2006, 02:14:59 PM »

Quote from: "TheCustomizer"

The fact is, Grade 8 bolts are designed to be more flexible than 5s, with a higher break point. Shear force will break a grade 5 before it bends, equivilent force will bend a grade 8 before it breaks. I have personally witnessed 3x3/8" grade 8s bend all the way around (no heat) until the tip touches the top (say that 5 times fast lol). Then the same 3x3/8" grade 5 *snap* under the pressure before it gets even near tip to top.

Actually a grade 5 will bend more than a grade 8 if kept within its yield and tensile loads. A grade 5 yield is 92 ksi and tensile 120 ksi and a grade 8 is 130 ksi yield and 150 tensile. A grade 5 will bend 30% and a grade 8 will bend 15%.

However I am not down playing the cheap insurance of going to a grade 8 over a grade 5, but when will a lot of these fasteners see 10,000 lbs + shear force, except for tow points.

Here is a great link for shear loads, http://www.rockcrawler.com/techreports/fasteners/index.asp

Author Topic: Axle U-Bolts (Read 4251 times)

Dragonmaster

TheCustomizer

TheCustomizer

Thatguy