Bolt size and strength

Discussion in 'Tech Area' started by Schoey, Jun 22, 2010.

  1. Schoey

    Schoey New Member

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    I would like to add another link to my drive chain to bring the rear axle back as far as I can. The problem is, the bolts that extends out to push the rear axle backward won't extend far enough. The size is M8-50 (grade 11). I found the size that will fit (M8-60), but its only a grade 8 bolt. Why does this boly have to be grade 11? Why couldn't it be a lower grade bolt? Does it really see that much stress?

    If this isn't good enough, where can I find a M8-60 in a higher grade?
     
  2. Jayson

    Jayson Highside Racing

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    The tech side of me tells me there must be a reason to use such a high strenght bolt, the pratical side of me can't figure out what that reason is. Bolt strenght is somewhat related to shear load and I can't see that much stress being put on that bolt, especially since the axle nut carries a significant clamp load.
     
  3. Schoey

    Schoey New Member

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    Another thing is that the swingarm is aluminium. There's no way that any grade of steel bolt would cause a problem, especially fastened to aluminium.

    There's an 11 stamped on the bolt head. This is the only thing that makes me think it's a grade 11. The bolt head itself is a 10mm.
     
  4. Ryan Whittle

    Ryan Whittle Rider of Orange V-Twins

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    But what does the frosted side tell you?
     
  5. Jayson

    Jayson Highside Racing

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    You don't want to see my frosted side!!!
     
  6. Jayson

    Jayson Highside Racing

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    usually metric bolts are x.x rated ... 8.8 or 10.9 etc

    imperial are rated with small //// marks, 3 /// marks being grade 5, 5 ///// marks being grade 8 etc etc..

    I've never seen a bolt with an 11 stamped on it.

    I would stop in at a bolt or industrial supply store, Fastenal would like be your best bet, and ask them what they think it is, I think any high strength bolt will do... engine mounts and frame sliders are 10.9, I can't see you needing aything that special.
     
  7. Gamma Nick

    Gamma Nick OFOF

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    Bolt Strength

    Schoey -

    I think the lower grade bolt will be fine. As long as your axle is adequately torqued there won't be an issue.

    Nick
     
  8. JAMR

    JAMR W M R C 1983, 84, 85

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    Last edited: Jun 23, 2010
  9. Schoey

    Schoey New Member

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    I invested $3 in some Home Depot M8-60 bolts that I think will do. I'll visit fastenall on the weekend to find out what the 11 stamped in there means. Being fastened into aluminum, I don't think it matters what strength it is. The aluminum will fail first.
     
  10. Simon

    Simon New Member

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    That will work fine, the chain adjusters don't really have any load if the axle is tightened properly.
     
  11. Schoey

    Schoey New Member

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    Found out today from Pacific Fasteners that the 11 marking is a manufacturers symbol and judging by the hardness of the bolt, it's not a high grade steel. A steel bolt will do, but don't stainless.

    Thanks for all the info people. I have what I need.
     

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