800GS shock bolt design flaw?

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

  1. BygDaddee

    BygDaddee Where do I get a pie

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    They look great, i reckon it will do the job fine
  2. Rider 101

    Rider 101 Time poor

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    Not so sure. I actually had the small bolt fracture and had to use the workshop of Monaro Motorcycles in Cooma to repair. The brace was the earlier version with the small bolt screwed into the brace.
  3. BygDaddee

    BygDaddee Where do I get a pie

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    Mmmmm, thats interesting, so it applied upward force onto the small bolt and sheared it ?

  4. Rider 101

    Rider 101 Time poor

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    Not sure if it was a bit of misalignment with the main frame tube. I ground the back side of the brace to take a nut ( ala version 2 ) and used an 8.8 instead of a 4.6 grade bolt. That was over 2 years ago and no problems since.
  5. Alohadmac

    Alohadmac Adventurer

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    I replaced the smaller subframe bolt with a stronger bolt as well (after reading your post). Did you use the best rest product or the shock brace from SoCal bmw? I was unaware of different versions of the shock brace. Both bolts went right in without any fitment issues.
  6. bakercdb

    bakercdb Still searching

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    Add another to the seriously bent shock bolt club. My 2015 F800GSA has been on the road it’s entire life
    At 25k miles I was in Germany and had Wilber’s install their WESA shock The bolt had a Tiny Bend then.

    Now, at 46k miles I’m in Africa chasing an electrical issue (fixed). But, I discovered a seriously bent shock bolt.
    And, I thought the issue was the weak OEM shock/spring, improper preload, or very heavy loading. I’m 160lbs, with 80lbs of panniers and gear.

    I stand corrected. It’s a bad design.

    Attached Files:

  7. ultane

    ultane sqeezin the bag

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    That really sucks. It IS a bad design!!!Has any of these bolts ever broken? Caused an accident? If so, the NTSB needs to know ASAP.


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  8. davidpetersen

    davidpetersen BestRest Adventurer

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    The bolts bend, they don't break. As they bend they also bend the mounting tabs on the frame. When the tabs bend far enough the frame is ruined, however I have talked to riders who were able to bend the tabs back using a sledge hammer and a 6-pack of beer.
    XTremeRide and MITOK like this.
  9. ultane

    ultane sqeezin the bag

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    Should the tabs be bent back into place after heating using a touch? It seams that doing so while the steal is cold will only fatigue and weaken the steel worse.


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  10. XRman

    XRman Long timer

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    I am not a boiler maker / metal worker, but I would have thought that heating would soften the metal to make it easier to shape, but also alter the grain structure. Quenching it after heating/ reshaping would be indicated possibly, like you see a blacksmith do?
    Done improperly the heating might make the frame likely to bend ( make it too soft where the tabs attach)
    ultane likes this.
  11. davidpetersen

    davidpetersen BestRest Adventurer

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    Heating the frame involves in a bunch of factors... protecting the components, paint being burned off, etc. I think a big TWANG with a sledge is a good way to go. I'd hold a short piece of 2x4 onto the tab with one hand, hold a beer in the other hand, then have your buddy swing a sledge with all his might.
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  12. XRman

    XRman Long timer

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    Nah Dave that is just stupid!
    Get your mate to hold the wood and you swing the heavy metal hammer.
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  13. Woody2627

    Woody2627 Grey Wobbler

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    Is the beer to ease the pain when he misses?

    The secret is to stop it happening in the first place, which BMW should have done 10 years ago. Or talk to Mr Peterson.
  14. bakercdb

    bakercdb Still searching

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    Here is the bolt from #1926 above (no that’s not my GS in the photo...)
    Came out with help of an air impact wrench and hammer.
    We bent the outside tab back a little bit. Fortunately, it doesn’t look like anything else bent, but afraid to look to close as nothing I can do here in Africa.

    I was able to find a class 12.9 bolt here in Namibia!
    I added a washer (lightly greased) as per the Touratech suggestion about 60 pages back, and loctite, and 110nm torque.

    I’ll add the BestRest brace as soon as I can arrange getting one.

    Attached Files:

  15. Pilotuh1b

    Pilotuh1b Been here awhile

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    It looks like a Kim kardashian belfie. Warped lines everywhere. Hahaha
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  16. MITOK

    MITOK Adventurer

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    I had the same issue, a tiny bend in the top shock bolt. This is a bad design, as mentioned -- BMW engineers should know that bolts are ideally used to take tensile loads only. They aren't bearings and they aren't structural members. The idea is that you should clamp the parts together so that the friction/fit between the two parts bears any shear stress, rather than allowing bending stress on the bolt.

    My solution was to buy a 12.9 grade bolt for two bucks and change from https://www.boltdepot.com/Product-Details.aspx?product=6618 and replace the original. Fairly simple. I know there are guys who make brackets etc but I'd rather just replace the bolt every year. The only finish they had was black oxide, so I glooped it with grease before installation to ward off the elements a bit.

    Probably should have used thread locker but....meh.
  17. BygDaddee

    BygDaddee Where do I get a pie

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    The 12.9 will still bend
  18. miotacztruskawek

    miotacztruskawek Adventurer

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    boltbraces my project

    [​IMG]

    [​IMG]
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  19. BuiltnotBought

    BuiltnotBought Perpetual Project

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    Re-reading this thread has made me put this mod on my list for this winter as a must. I went through a bit of rough stuff last summer in WV, curious to see what effect it had on my shock bolt. Probably will end up making my own brace, I'll post pics of it when I get it sorted.
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  20. MITOK

    MITOK Adventurer

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    Maybe, but by definition yield stress should be higher. So it will take more extreme riding to bend. Short of building a new mount or a brace i cant think of a better way to improve the stock upper mount.
    BygDaddee likes this.