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Leon B MO 
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Joined: 12 Sep 2009
Location: Old Monroe, Mo
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 Topic: ARP 8740 rod bolt?
Posted: 16 Jan 2023 at 11:44am |
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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
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Uncle always said "Fill the back of the shovel and the front will take care of itself".
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steve(ill)
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Joined: 11 Sep 2009
Location: illinois
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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
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Like them all, but love the "B"s.
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SteveM C/IL
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Location: Shelbyville IL
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Posted: 16 Jan 2023 at 7:15pm |
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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
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Location: Paris Tn
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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...
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When told "it's not the money,it's the principle", remember, it's always the money..
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SteveM C/IL
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Posted: 17 Jan 2023 at 10:02am |
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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
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Joined: 12 Sep 2009
Location: Old Monroe, Mo
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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
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Uncle always said "Fill the back of the shovel and the front will take care of itself".
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55allis
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Posted: 17 Jan 2023 at 10:32pm |
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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…
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1955 AC WD45 diesel with D262 repower, 1949 AC WD45
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steve(ill)
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Location: illinois
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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.
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Like them all, but love the "B"s.
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SteveM C/IL
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Posted: 18 Jan 2023 at 12:50pm |
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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
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Posted: 18 Jan 2023 at 1:52pm |
 .
Edited by Mikez - 18 Jan 2023 at 1:53pm
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Mikez
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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
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Posted: 18 Jan 2023 at 11:09pm |
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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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