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  1. #11
    suck my wake's Avatar
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    Quote Originally Posted by davus View Post
    Hi All,

    Id like to start a logical and "non flamatory" conversation around head bolt re-use. Yes, I know there's been dozens of posts about this, but to be honest, most of them either seem to go nowhere, or they just nosedive into unsubstantiated and uneducated comments being thrown around.

    There to be four sets of opinion on this.

    1) Reuse is fine. "Ive been doing it for years and never had an issue"
    2) Reuse is ok as long as the bolts are within Seadoo spec.
    3) I never reuse them, but thats only because thats what ive been told.
    4) I never reuse them because I got substantiated documentation / consistent evidence to support.

    With respect to point 1, I feel like this is probably more the person who is either completely frugal, refuses to buy into the hype of "do what others say", or simply cant be bothered doing the homework.

    With regards to point 2, this seems to be the group that likes to challenge "the flock", but still open to being convinced that their thoughts aren't completely accurate.

    With regards to point 3, I think this is the group that have either run into (or heard of) a few head bolt issues over their time, or have some solid official information (credible) as to why these bolts shouldn't be reused (definitively).

    Prior to 2006, official seadoo manuals specifically stipulated that head bolts could be reused.



    Then, after 2005, for some reason, the manuals changed to specifically state that the bolts had to be changed.



    Now, I've heard / read a few different reasons as to why this is so. None of which have been corroborated by anyone official (or any official documentation / tech bulletin).

    Reason 1: Seadoo technicians continually stuff up the correct torquing process of used head bolts, causing issues with engine. This prompted Seadoo to change their tact and simply says "new head bolts all the time"

    Reason 2: The metal construct of the bolts changed in 2006 prompting Seadoo to have to change their manuals (although i can find no tech bulletin supporting this).

    Reason 3: The makeup of the block / head changed, meaning new bolts had to be used.

    Now - None of these are my reasons, and im not saying i subscribe to any of them, im just saying these are what ive read / heard.

    So, one part of my brain deduces that without any official reason behind the change of direction, then logically the bolts can be re-used.

    Another part of my brain tells me that "Well seadoo knows best, so we should what the latest technical documentation says"

    While another part of my brain says "Seadoo is a Company. Companies need to make profits, and they do this by selling stuff".

    Honestly, im not convinced which part of my brain is the winner at this stage. But what i do know is that there is supported logic for both sides.

    Im interested in hearing from people who are well educated, from any of the four "camps" (sets of opinions), to help me understand where the "truth" lies.

    And for the record, im not trying to tight arse here. I'm a naturally inquisitive person and im trying to figure out why the data ive gathered to date is so disparate.

    Look forward to reading the replies.

    Dave
    According to my 2006 service manual there is a service limit measurement that suggests the head bolts can be reused if they fall within spec. That being said on the oem level these fasteners are "economical" and offer just enough clamping force for the oem application. Torque to yield fasteners are only used on the oem level. If your ski is bone stock and you will never ever modify it then the oem fasteners will be all you need. If you modify your ski with higher rpms, bigger boost superchargers, steeper pitch props you should not use Torque to yield head bolts. Will they work, sure.....will they last and endure like arp head studs No! The torque to yield or "stretch bolts" do not offer uniform Torque which can lead to blown head gaskets at some point. Higher boost can actually lift the head off the block and if you are using a stretch fastener they can actually stretch further and will at some point allow the cylinder pressures to escape into the cooling passages causing the system to over pressurize and blow coolant out of the over flow tube. There is no down side to upgrading to arp studs. Over thinking the use of and or re use of the oem head bolts is really just a waste of time.

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  3. #12

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    Quote Originally Posted by suck my wake View Post
    According to my 2006 service manual there is a service limit measurement that suggests the head bolts can be reused if they fall within spec. That being said on the oem level these fasteners are "economical" and offer just enough clamping force for the oem application. Torque to yield fasteners are only used on the oem level. If your ski is bone stock and you will never ever modify it then the oem fasteners will be all you need. If you modify your ski with higher rpms, bigger boost superchargers, steeper pitch props you should not use Torque to yield head bolts. Will they work, sure.....will they last and endure like arp head studs No! The torque to yield or "stretch bolts" do not offer uniform Torque which can lead to blown head gaskets at some point. Higher boost can actually lift the head off the block and if you are using a stretch fastener they can actually stretch further and will at some point allow the cylinder pressures to escape into the cooling passages causing the system to over pressurize and blow coolant out of the over flow tube. There is no down side to upgrading to arp studs. Over thinking the use of and or re use of the oem head bolts is really just a waste of time.
    Great response thanks.

  4. #13
    ncdoo's Avatar
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    If you've researched the issue I am curious to why you even posted the question as you basically got a rehash of everyone's previously posted opinions on the subject.

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  6. #14
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    I don't understand WHY at a minimum anyone wouldn't purchase new OEM bolts. Their a whopping $12 each. Unless you're just trying to cut EVERY corner possible I personally don't understand the question. If/when I build or have the mill built in my 255 it WILL have studs. RR


  7. #15

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    Head Bolt reuse. Sick of conflicting stories and uneducated "Opinions"

    Quote Originally Posted by ncdoo View Post
    If you've researched the issue I am curious to why you even posted the question as you basically got a rehash of everyone's previously posted opinions on the subject.
    Edited

  8. #16
    Bob 1tommygunner1927's Avatar
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    Simply put, used stretch bolts (head bolts/rocker arms) should never be reused. Buy new OEM stretch bolts (for stock rebuilds) or head studs for modified engines.

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  10. #17
    suck my wake's Avatar
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    Quote Originally Posted by davus View Post
    Great response thanks.
    Also keep in mind that once you stretch the bolts initially you have changed their integrity, if you reuse them and stretch them again they essentially will become weaker and not have the same clamping force as they did when new. I tried once to reuse a set and had one bolt just keep stretching and wouldn't degree out so I stopped in fear of breaking it and just replaced them all with new


  11. #18
    This topic comes up quite often, maybe it has been 5 years since it last came up. You all are forgetting the purpose of the head bolts, as well as forgetting about expansion and contraction of aluminum. So let me educate you, again....

    The purpose of of using Torque To Yield (TTY) bolts is to provide a uniform clamping pressure over the range of operation temperature cycling, and over time.

    Here is how this works:

    - When you reach the yield point of the bolt (the angle setting), the bolt has its limit of clamping pressure.
    - This yield range stays relatively stable as expansion of head and block occur over temperature
    - This yield range stays relatively stable over time

    ARP and other aftermarket studs don't work the same way. Yes, you can achieve much higher clamping pressures, which are good for higher horsepower, modded applications. But these are not stable over temperature and time. The clamping pressure can vary over temp range and over time. This is why you need to retorque these studs. For performance, and if you maintain your ski to include retorque, sure studs are great. But they are terrible for the average user, and terrible to use if you are not going to be managing them over time.

    The TTY head bolts that BRP uses are reusable, just like the ones that Mercedes and other high end manufacturers use. Why did BRP change the specs later on? I suspect that they got a lot of shade tree mechanics that didn't understand how these work, and many never measured the bolts and simply reused them. (it is kind of like the warning stickers they put on the skis "NEVER CHARGE OR BOOST BATTERIES WHEN IN THE SKI!" It is perfectly fine to charge or boost your battery in the ski. They put this warning because of all the idiots that hook up the charger or jumper cables backwards...)

    FWIW, I have personally found a number of head bolts that reach a yield point less than others. (when you have been wrenching for almost 50 years, you can tell by feel) I have found this with brand new bolts as well. I don't know if it is a quality issue or what. When I have come across these, I simply toss them. (BTW, they came out with TTY bolts during WWII for aircraft engines. They taught the mechanics how to determine the proper yield point by feel, not by torque.)

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  13. #19
    88-jac's Avatar
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    I stand by what I said - theyre junk, replace with proper ARP studs!


  14. #20
    Quote Originally Posted by 88-jac View Post
    I stand by what I said - theyre junk, replace with proper ARP studs!
    You are not following the rules by the OP, which clearly say "no uneducated opinions"

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