Stretched conrod bolt
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Thread: Stretched conrod bolt

  1. #1
    1000+ Posts PugMonkey's Avatar
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    Default Stretched conrod bolt

    Hi all,
    Back into building my engine but struck an issue. I have stretched a conrod bolt. What can I do? New conrod or can an engineer replace the thread? Can't post a Pic yet.

    Sent from my HTC One M9 using aussiefrogs mobile app

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  2. #2
    1000+ Posts PeterT's Avatar
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    Buy a new conrod bolt. They aren't very expensive. How do you know you stretched it? Were you using a conrod micrometer?
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    '92 205 Mi16
    '90 Mi16x4

  3. #3
    1000+ Posts PugMonkey's Avatar
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    I was torquing it down and it just didn't want to tighten so I undid the nut to discover the stretch. Torque used was 39 ft lb from memory

    Sent from my HTC One M9 using aussiefrogs mobile app
    ....now watch a Peugeot turn into a corner!

  4. #4
    COL
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    Quote Originally Posted by PugMonkey View Post
    I was torquing it down and it just didn't want to tighten so I undid the nut to discover the stretch. Torque used was 39 ft lb from memory

    Sent from my HTC One M9 using aussiefrogs mobile app
    Better to fail when torquing down than fail at 7000 + RPM

    I would go with Peter's suggestion in post #2
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    Regards Col

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    Just as an aside, years back we used to prepare vintage racing engines with new hi tensile Allen head socket bolts secured with hi tensile nylock style nuts as you could not buy the hi tensile replacement conrod bolts, they worked better than trying to use old deformed conrod bolts, none of the Allen bolts failed in service. here is a link to available similar hi tensile similar bolts.

    https://www.bing.com/images/search?q...es&FORM=RESTAB

    Ken
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  6. #6
    1000+ Posts PeterT's Avatar
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    It sounds like you've "stripped" the thread rather than stretched the bolt. Stuffed nether the less. You could either buy one new rod bolt & nut from Peugeot, or a complete set of ARP bolts from someone like Rocket Industries. I'd probably do the later. Price will be similar I'd expect.
    Bustamif and driven like this.

    '92 205 Mi16
    '90 Mi16x4

  7. #7
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    I'd also replace the clutch pressure plate bolts, these do stretch as I have found.

  8. #8
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    Pic. Thread is not stripped. I have another con rod to use. 1565253581649.jpeg

    Sent from my HTC One M9 using aussiefrogs mobile app
    ....now watch a Peugeot turn into a corner!

  9. #9
    1000+ Posts PeterT's Avatar
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    Definitely past it's yield point! You don't need a micrometer to work that out. Great steel though.

    '92 205 Mi16
    '90 Mi16x4

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