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ARP 8740 rod bolt?

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Leon B MO View Drop Down
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Joined: 12 Sep 2009
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Leon B MO Quote  Post ReplyReply Direct Link To This Post Topic: ARP 8740 rod bolt?
    Posted: 16 Jan 2023 at 11:44am
A friend of mine is putting new rod bearings in his 8070 and noticed the bolts are ARP 8740. He just wanted to verify that that is a high quality bolt and verify what torque spec for that bolt.
Thanks
Leon B Mo
Uncle always said "Fill the back of the shovel and the front will take care of itself".
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steve(ill) View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote steve(ill) Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2023 at 5:42pm
ARP 8740 is a high quality chrome moly material for rod 
bolts... They come in 3/8 and 7/16 diameters and a couple different lengths.. Torque varies slightly depending on what you got.

example...

Highlights:

  • ARP 8740 - 190kpsi tensile strength, 180kpsi yield strength
  • 7/16" thread
  • 1.75" under-head length
  • 7/16" 12pt socket size
  • torque to 63 ft-lbs with ARP moly lube only
  • Stretch to .0059"-.0063"
  • Use either torque method or stretch method - DO NOT use both!

Eagle rod bolts are manufactured by ARP to Eagle's specifications. These are not off-the-shelf ARP bolts. Always use Eagle's bolts with Eagle rods.



Edited by steve(ill) - 16 Jan 2023 at 5:46pm
Like them all, but love the "B"s.
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SteveM C/IL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveM C/IL Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2023 at 7:15pm
Bolts from AGCO come with instructions.....torque,loosen,torque, loosen,torque,loosen final higher torque.   I think it was 3 times...if not then 2. Seems odd to me but I didn't design em.
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tbran View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tbran Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 2023 at 8:18pm
That means the engine has been into before - I would check with ARP - many high quality rod bolts such as the ARP bolts shold not be reused ... We have never failed an engine's bottom end when using ARP bolts from AGCO...

When told "it's not the money,it's the principle", remember, it's always the money..
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SteveM C/IL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveM C/IL Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 2023 at 10:02am
Like Tim says,they are not to be reused. If you think they are pricey, consider what a failure will cost.
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Leon B MO View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Leon B MO Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 2023 at 6:52pm
Thanks guys for the replies. I'll print this out and give it to him. He thought maybe buying new through Agco would be best. 
Leon B MO
Uncle always said "Fill the back of the shovel and the front will take care of itself".
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55allis View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 55allis Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 2023 at 10:32pm
When I put arp head studs in my d19D engine I called them and they told me that I could redo them 5 or 6 times as long as they are in good shape, but that was for head bolts not rod bolts…
1955 AC WD45 diesel with D262 repower, 1949 AC WD45
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steve(ill) View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote steve(ill) Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2023 at 8:44am
GOOGLE......

No, ARP bolts are not torque to yield (TTY). TTY fasteners, when being torqued, actually stretch because of the elastic properties of the material. This gives them the needed clamping force, but the downside it that they aren't reusable (well, at least they shouldn't be reused). The upside here is that ARP bolts can be reused over and over again.
Like them all, but love the "B"s.
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SteveM C/IL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveM C/IL Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2023 at 12:50pm
It seems the final torque was 80lb/ft. That's alot on that size bolt. Don't know if it gets it's stretch at that number and causes "yield". Pretty sure the paper with instructions said not to reuse. I'd have to hear it from ARP but when my mechanic called them in 2010,they wouldn't even own up to making the AGCO rod bolt.

Edited by SteveM C/IL - 18 Jan 2023 at 12:57pm
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Mikez View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mikez Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2023 at 1:52pm
.

Edited by Mikez - 18 Jan 2023 at 1:53pm
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Mikez View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mikez Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2023 at 1:55pm
can you read that. Its 4 pages want the other pages. Or I can email to you.
Is that what you guys talking about
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SteveM C/IL View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveM C/IL Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2023 at 11:09pm
That's it Mike. Speaks to the new bolts in later pages. Tells torque procedure.

Edited by SteveM C/IL - 18 Jan 2023 at 11:10pm
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