Toyota OEM Bolt Markings

Discussion in '80-Series Tech' started by Cj80cruiser, Sep 7, 2012.

  1. Cj80cruiser

    Cj80cruiser

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    Opelika, AL
    I recently purchased bolts from a dealership but need to verify bolt quality. They don't have the typical grade marks on the head like a metric bolt would (8.8,10.9 etc) Is there a chart I can use to identify this?

    Thanks for any help
  2. Mattnatti

    Mattnatti See a Doctor and get rid of it. SILVER Star

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    Location:
    Cincinnati
    I think the FSM has Toyota bolt marking chart in it.
  3. Kernal

    Kernal

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    4,829
    This is from an FSM:

    Attached Files:

  4. Cj80cruiser

    Cj80cruiser

    Messages:
    1,570
    Location:
    Opelika, AL
    For some reason my device wont open the link but I found another FSM with the specs.

    Disregarding price, is a higher grade bolt always better than a lower grade bolt? This may sound like a ridiculous question but here is the arguement

    " Anyway, I know I have said it a million times, but be careful of going and replacing important bolts with "better" ones; there is a whole host of reasons Toyota might have used "lower grade" bolts rather than higher grade ones not including cost.

    1. Lower grade bolts can often tolerate more strain. Hardness and ultimate tensile strength are typically a trade-off with elasticity. Different loading conditions favordifferentstrain properties.

    2. Lower grade bolts won't strip out your knuckle as easily. Differential hardness and UTS are used to prevent damage to mating components for many reasons. For example,you typically can rip a lug nut straight off a lug, and the lug threads won't be badly damaged because the lug is a much higher grade or different temper. Thisis strategic design,and can be used to eliminate multiple failure modes, or unpredictable failure modes.

    3. Different tempers can be affected by heat exposure, so if you are exposing them to high heat, like right near the brakes, then over time they can lose their temper

    4. Precise shoulder lengths may vary. Any bolt under shear probably has a shoulder placed precisely to prevent shear on the threads. aftermarket bolts may not have the exactshoulder length, and may cause shear on the threads, greatly reducing the effective strength of the bolt in application.

    5. The bolt may intentionally be the weakest link in a system. Again,thisistypicallydone to eliminate other failure modes and make failure easier to predict.

    You will probably be fine with high grade bolts, but by getting new OEM, the numbers are on your side, and you will probably be less likely to damage mating components. And with aftermarkets, you are definitely losing some behind the scenes engineering, probably alot of behind the scenes engineering."

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