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blakews2217
October 19th, 2017, 20:08
So set out to change the upper and lower CA bushings after work. Lowers went fine. First upper I get to and I lose a socket to the unibody and round the heads on the body side. There stamped 10.9 to I'm looking at grade 10 bolts. Any ideas?


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Green XJ Jeep
October 19th, 2017, 20:56
10.9 is metric and corresponds to roughly a grade 5 or 6 bolt

blakews2217
October 19th, 2017, 21:44
10.9 is metric and corresponds to roughly a grade 5 or 6 bolt



Really? I'm used to SAE bolts in machines that usuly have the grade stamped on the heads. My question is why such a low grade bolt for suspension? Why not grade 8?


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Green XJ Jeep
October 19th, 2017, 21:58
From what I have been told for clamping force grade 8 for anything that has a side load grade 5.
Supposedly the grade 5 can handle more side pressure than an 8 can due to it being softer.
https://www.rockcrawler.com/2003/04/fasteners-making-the-grade-a-technical-discussion/

Info on metric fasteners,
https://www.fastenal.com/en/76/metric-system-and-specifications

Ralph77
October 20th, 2017, 02:35
10.9 is metric and corresponds to roughly a grade 5 or 6 bolt

My understanding is that a Class 10.9 is pretty much the equivalent of a Grade 8 and Class 8.8 is pretty much a Grade 5.

http://www.fastenermart.com/understanding-fastener-grades-and-classes.html

Jeep Driver
October 20th, 2017, 05:47
My understanding is that a Class 10.9 is pretty much the equivalent of a Grade 8 and Class 8.8 is pretty much a Grade 5.

http://www.fastenermart.com/understanding-fastener-grades-and-classes.html

That's correct.

This is Tech, and we want to be correct in Tech.

Let it be noted that Greeny is giving out bad and incorrect advise in Tech.

Greeny, it's shear, not side forces. And yes, clamping force matters.


OP, get a grade 8 bolt.

md21722
October 20th, 2017, 05:53
The factory flag bolts do not have heads that a socket fits. They are designed to be loosened from the nut side. I replace them with M10X1.5X70 10.9 bolts and 10.9 nuts.

Jeep Driver
October 20th, 2017, 05:56
The factory flag bolts do not have heads that a socket fits. They are designed to be loosened from the nut side. I replace them with M10X1.5X70 10.9 bolts and 10.9 nuts.

They are not all 'flag' bolts, early are torx.

He's in IL, rustbucket state.

Green XJ Jeep
October 20th, 2017, 07:29
My understanding is that a Class 10.9 is pretty much the equivalent of a Grade 8 and Class 8.8 is pretty much a Grade 5.

http://www.fastenermart.com/understanding-fastener-grades-and-classes.html

Not exactly. That chart will work.
A 10.9 bolt is 900mpa which equal 130k psi. A grade 5 bolt is 120k psi and an 8 is 150k psi.

For the op's intended purpose a grade 8 will work just fine.

Green XJ Jeep
October 20th, 2017, 07:36
That's correct.

This is Tech, and we want to be correct in Tech.

Let it be noted that Greeny is giving out bad and incorrect advise in Tech.

Greeny, it's shear, not side forces. And yes, clamping force matters.


OP, get a grade 8 bolt.
When did you ever concern yourself with giving out correct information?
90% of your posts are full of wrong or incorrect info that you will defend to the end even when you are proven wrong.

Please point out the incorrect info i posted in this thread.

I know exactly what forces are applied to a bolt and attempted to use easily understood terms.

I at least can cite resources to back up what i post

Failed attempt at trolling.

lawsoncl
October 20th, 2017, 10:43
From what I have been told for clamping force grade 8 for anything that has a side load grade 5.
Supposedly the grade 5 can handle more side pressure than an 8 can due to it being softer.
https://www.rockcrawler.com/2003/04/fasteners-making-the-grade-a-technical-discussion/


This is an urban legend. From the article you posted:
"I hope itís very clear by now that grade 8 fasteners are far superior to grade 5 fasteners."

If anything you want a harder bolt in shear so it doesn't deform, and when clamping you want something with a little more stretch. In all but some very rare cases, a grade 8 is superior to a grade 5. For suspensions, as long as the grade-5 bolt is properly sized you're probably going to rip out the surrounding structure before you break a new non-rusty bolt. Just don't buy cheap ungraded Chinese bolts from home depot any you'll be fine.