800GS shock bolt design flaw?

Discussion in 'Parallel Universe' started by johngil, Jul 16, 2009.

  1. MontanaPaul

    MontanaPaul Adventurer

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    into the weeds alert:
    MPascals are SI units of pressure = force/unit area (eg Newtons/square meter). In describing bolt strength, it's the proper unit of the shear modulus

    ft lbs are a unit of torque = force*length (eg Newton-meter). No direct conversion.

    However, a little algebra applied to this specific situation (the bolt pitch and area (washer?)) gives a sketchy conversion:
    P = (2 * pi * torque * pitch)/(area ). Solve for torque
    Then units conversion can be applied from SI to imperial. Is this how you arrived at the 23k ft lbs?

    All sort of moot, as everyone has observed, proper preload prevents poor performance
  2. DFVans

    DFVans Adventurer

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    Nope, did not bother with any extra math, and yes, your right in terms of what qualities they are measuring. I am aware. What I found was a conversion table that had these to measurements directly opposed from one another on a chart(they did the math) There is not a direct conversion? no. however there are many pages on the interweb that do have these kinds of conversion charts. I simply used a conversion charts numbers and the numbers avail. in the earlier post. That is good enough for me and maybe some others? apples and bananas? Yes. I don't trouble myself too much about the academic aspects of the math necessary to sort out the details of a shock bolt on my bike . I wanted to get and idea of what the 15% meant in terms of a measurement that I understand, even if it's not applied correctly.. To that result, success. and yes, moot for sure, however I am new to the bike.....so a learning curve for me.... I just saved the $ buying an unnecessary bracket.
  3. All-Terrain

    All-Terrain Adventurer

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    So we know the factory bolt will bend, and we know about the associated damage.

    Can we categorically say now that the aftermarket brace with 12.9 bolt resolves this situation?

    Or does it just extend the time until bending, and then create the same (or worse) damage?
  4. Motoriley

    Motoriley Still riding like crap after all these years.

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    With the Indy mod it won't bend. Don't know about the Best Rest solution. Even if the bolt bends slightly and you keep changing it so the frame doesn't get bent nothing bad will happen.

    BygDaddee, ultane and All-Terrain like this.
  5. Rider 101

    Rider 101 Time poor

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    I changed the original very early and fitted the best rest brace with a 12.9. I changed the bolt 4 years later and modified the brace to use a nut on the frame bolt as per later versions. The bolt had a very slight bend but nothing to worry about. I measured the frame with verniers and there didn't appear to be any bending.
    The bike was used from easy day rides to multi day off road rides loaded with a week's supplies.
    All-Terrain and malloy like this.
  6. ambor

    ambor n00b

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    I bought a 2009 F800 at the start of the year. I was vaguely aware of this problem but never got around to checking for it. I saw a trip report on bookface where another F800 (year unknown) found his bolt was bent after last weekend, so I checked mine, and low and behold mine was bent too.

    So its still happening (or maybe mine happened 10 years ago and I just found out).
    I P.M.ed Indy and he hasn't made the kit for years and recommends the best rest as the next best option. Just sucks that I live in Australia and with the conversion rate at the moment an US$86 part ends up being AU$180 delivered.
  7. Flopix

    Flopix Adventurer

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    I installed the Best Rest kit 3 years ago, only a few months after I got my 2013 F800GS. Everything is fine, and I've done some pretty hard stuff with the bike, including 2 weeks offroad in Utah, fully loaded with camping gear, etc.
  8. Rider 101

    Rider 101 Time poor

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    Try contactt
    Try contacting mscmoto.com.au Don't quote me but I have a suspicion they actually developed the brace. I know that mine came from them in 2011

    Failing that a good machine shop could spin up the Indy kit. Contact him for the drawing. ( I have copy if Indy ok for me to send to you). I also have a couple of 12.9 screws.
    rwcfrank01 and BygDaddee like this.