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  1. #31

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    This thread is amusing.


    I won't muddy the waters about how we measure bolt stretch in a test block before using and reusing them on multi-million dollar aircraft....you know, because people who reuse TTY bolts are cheap asses and all that, and a multi-billion dollar company like Gulfstream and Boeing and people who follow their procedures are such cheapskates. Yup, just throw new BRP bolts in, they TOTALLY will work right out of the bag 100% of the time, yup. Everyone the past 5 years saying they had bad bolts are just liars. Go with that. Even people who spin wrenches for a living, they are liars, too.

    /S

  2. #32
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    Quote Originally Posted by davus View Post
    Youíre missing the point. Iím not saying itís right or wrong to use new head bolts, Iím looking for educated responses.

    One of the questions was why BRP changed their stance on it. This may not intrigue you, but it does intrigue me.
    Probably realized, from warranty work, that failures were higher when bolts were re-used.

    Power level have also increased since the early days so re-used bolts may not be up to the job.

  3. #33
    canuck's Avatar
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    The question of why BRP changed the manual from reuse if OK to replace will never be answered unless we can get an insider at BRP to explain why the change and that's not going to happen anytime soon.

  4. #34

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    Quote Originally Posted by Highboosted View Post
    This thread is amusing.


    I won't muddy the waters about how we measure bolt stretch in a test block before using and reusing them on multi-million dollar aircraft....you know, because people who reuse TTY bolts are cheap asses and all that, and a multi-billion dollar company like Gulfstream and Boeing and people who follow their procedures are such cheapskates. Yup, just throw new BRP bolts in, they TOTALLY will work right out of the bag 100% of the time, yup. Everyone the past 5 years saying they had bad bolts are just liars. Go with that. Even people who spin wrenches for a living, they are liars, too.

    /S
    Mate it sounds like thereís some good background experience there, but Iím a little confused.

    Are you saying on your industry they ARE are reused (if within spec), or they are NOT reused?

    Sorry, not quite following what you were saying.

    Dave


  5. #35

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    Quote Originally Posted by davus View Post
    Mate it sounds like there’s some good background experience there, but I’m a little confused.

    Are you saying on your industry they ARE are reused (if within spec), or they are NOT reused?

    Sorry, not quite following what you were saying.

    Dave
    The /S means the above was dripping wet with sarcasm.

    Yes, we reuse certain TTY bolts, and in certain critical applications you must measure the actual bolt stretch length while being torqued and compare the torqued length of the bolt to it's turning torque value in a chart to ensure the bolt is actually providing the engineered clamping force and is within it's elastic range of it's stretch curve. This applies to brand new bolts as well, because just because a single bolt costs $150 and is X-ray inspected and comes with it's own serial number for tracing before being shipped to you does NOT mean it's without fault, and it happens.

    easy example without explaining clamp load fixtures: in a certain TIO engine you measure every con rod bolt's length during torqueing with a micrometer since both ends of the bolt are accessible, and if the bolt reaches a certain length before each step torque procedure and during the angle portion, you remove it and throw it away, even if brand new. Usually you end up throwing away 1-2 new bolts out of 30, about half the reused bolts pass spec depending on hours and cycles. Use that info how you will, I will not advocate for either blindly reusing or just throwing new bolts at an engine if you can't "feel" if it's right. It's not really subtle when it doesn't torque up right, it's like a bolt that's starting to strip, you just know when it's F-ed up and the wrench moves more or easier than all the other bolts did. That's why they teach you consistency in torque wrench placement so the wrench is at the same angle when torqueing fasteners, you can instantly know if a bolt took 10 degrees more movement than the rest for the wrench to beep at you, so you know to throw that one away or figure out why it was different than the rest.

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  7. #36
    Quote Originally Posted by 1tommygunner1927 View Post
    See post 10......It too was a new stretch head bolt. It broke mid way through the torque sequence at 65 ft/lbs (88 Nm).
    I read that thread, it seems you did a newbie error and hydrolocked the bolt? That has nothing to do with this topic, it was an error on your part.

  8. #37
    Bob 1tommygunner1927's Avatar
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    Quote Originally Posted by canuck View Post
    The question of why BRP changed the manual from reuse if OK to replace will never be answered unless we can get an insider at BRP to explain why the change and that's not going to happen anytime soon.

    For the same reason they charged supercharger rebuilds from 100 hours to 200 hours......and you're out of warranty!

  9. #38
    Quote Originally Posted by Highboosted View Post
    The /S means the above was dripping wet with sarcasm.

    Yes, we reuse certain TTY bolts, and in certain critical applications you must measure the actual bolt stretch length while being torqued and compare the torqued length of the bolt to it's turning torque value in a chart to ensure the bolt is actually providing the engineered clamping force and is within it's elastic range of it's stretch curve. This applies to brand new bolts as well, because just because a single bolt costs $150 and is X-ray inspected and comes with it's own serial number for tracing before being shipped to you does NOT mean it's without fault, and it happens.

    easy example without explaining clamp load fixtures: in a certain TIO engine you measure every con rod bolt's length during torqueing with a micrometer since both ends of the bolt are accessible, and if the bolt reaches a certain length before each step torque procedure and during the angle portion, you remove it and throw it away, even if brand new. Usually you end up throwing away 1-2 new bolts out of 30, about half the reused bolts pass spec depending on hours and cycles. Use that info how you will, I will not advocate for either blindly reusing or just throwing new bolts at an engine if you can't "feel" if it's right. It's not really subtle when it doesn't torque up right, it's like a bolt that's starting to strip, you just know when it's F-ed up and the wrench moves more or easier than all the other bolts did. That's why they teach you consistency in torque wrench placement so the wrench is at the same angle when torqueing fasteners, you can instantly know if a bolt took 10 degrees more movement than the rest for the wrench to beep at you, so you know to throw that one away or figure out why it was different than the rest.
    This reminds me of an example with an aircraft engine, I seem to recall a Lycoming? A lot of people, including engineers, tend to think "stronger is better", just like this discussion with ARP studs. On a particular aircraft engine, they switched to stronger, fatter non-TTY connecting rod bolts, (just like ARP studs) and promptly started seeing failures. The hammering stresses of the connecting rod fractured the "stronger" bolts, whereas when they went back to smaller TTY, bolts the problem disappeared. The hammering strains to the bolts in a more plastic state didn't fracture them.

  10. #39
    Bob 1tommygunner1927's Avatar
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    Quote Originally Posted by Sea Dood View Post
    I read that thread, it seems you did a newbie error and hydrolocked the bolt? That has nothing to do with this topic, it was an error on your part.
    LOL...you sir are correct; a newbi error on my part, nearly 8 years ago. Used compressed air to clear any coolant/oil and head gasket material which may have fallen in the bolt holes prior to installing new stretch bolts.....

    The point was about cleaning those bolt holes after a blown head gasket due to adding more boost via a larger S/Cer. So, to say it again, stock stretch bolts for stock rebuilds, head studs for modified engines.

  11. #40
    Bob 1tommygunner1927's Avatar
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    Quote Originally Posted by Sea Dood View Post
    This reminds me of an example with an aircraft engine, I seem to recall a Lycoming? A lot of people, including engineers, tend to think "stronger is better", just like this discussion with ARP studs. On a particular aircraft engine, they switched to stronger, fatter non-TTY connecting rod bolts, (just like ARP studs) and promptly started seeing failures. The hammering stresses of the connecting rod fractured the "stronger" bolts, whereas when they went back to smaller TTY, bolts the problem disappeared. The hammering strains to the bolts in a more plastic state didn't fracture them.
    So, now we are comparing aircraft parts (highly regulated) to SeaDoo parts? LOL

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