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Correct caliper bolts

Discussion in 'VF Holden Commodore (2013 - 2017)' started by Ron Burgundy, Dec 14, 2018.

  1. lmoengnr

    lmoengnr Well-Known Member

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    They have a single use, thread locker applied to the bolt.
    Not sure about TTY on the Brembo's fitted to Holden's, but the caliper bolts on HSV AP calipers just have a torque figure.
     
  2. dgp

    dgp Well-Known Member

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    The manual says to replace the bolts, but does not say that they are TTY, it does say to torque them then to 40Nm plus 90 degrees. I have cleaned old loctite off caliber bolts in the past and reused them after applying new loctite.
     
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  3. EYY

    EYY Well-Known Member

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    They probably only say to replace bolts because of the loctite on them
     
  4. dgp

    dgp Well-Known Member

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    I was thinking this too.
     
  5. Ron Burgundy

    Ron Burgundy Well-Known Member

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  6. EYY

    EYY Well-Known Member

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    But is it a torque to yield or torque to angle fastener? It's important to know the difference. Torque to angle is also very common as it ensures more accurate torque application because friction plays a considerable role when tightening fasteners beyond a certain point. That's why most critical bolts are torque to angle - as it results in greater accuracy.

    Most of the time tty bolts have a slightly reduced shank where the stretch occurs. Toyota even specify that you can reuse tty bolts providing you check the length of the old bolt with the length of a new bolt. If they haven't stretched then you're good to go. But it's cheap insurance to replace them wherever possible, especially with something critical or difficult to replace like head bolts, rod bolts etc.
     
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  7. BlackVXGTS

    BlackVXGTS Well-Known Member

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    Interestingly, the Holden Workshop manual says front caliper bolts on VFs are 40Nm + 90 degrees, except for HSVs which are 160Nm. All rear caliper bolts are 110Nm.
     
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  8. 3rspecB

    3rspecB Well-Known Member

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    The Holden torque + angle spec delivers a higher final torque than 160nm ;)
     
  9. Ron Burgundy

    Ron Burgundy Well-Known Member

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    Sooo if the torque and angle is for instance equivalent to 180nm why would not they just say 180nm torque rather than x torque + x degrees...
    I am sure there is a goid reason for this...i just don't know the answer :)

    Edit.
    This explains it. It is basically a lot more precise...

     
    Last edited: Sep 11, 2019
  10. Mattricho

    Mattricho Active Member

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    I was under the impression that if you’re given a torque setting of x plus x degrees that it is for torque to yield bolts and that the x degrees is for the bolt to stretch. (Meaning single use)

    Where as if your given a torque setting of x and that’s it then you can reuse the bolts
     
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  11. wetwork65

    wetwork65 A wet business

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    Yes agree. The angle stipulated is more precise and will give a known percentage of strain by a direct calculation. (i.e. the distance along an inclined plane, which is the nut travelling along the thread)
    If the bolt is being stressed beyond yield, then the bolt will start to go "loose" and be on its path to failure. Thus I would not expect these to be torque to yield.
    Anyone here recall the stress/strain graph from Mech Eng days?
     
  12. vc commodore

    vc commodore Well-Known Member

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    What I find rather humourious about this thread is, I have never seen anyone, nor have I used a torque wrench on caliper bolts, when ever they have been removed and put back in.

    And I've done thousands, and seen just as many being done and never ever had issues.....
     
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  13. wetwork65

    wetwork65 A wet business

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    I use a torque wrench to make sure they are done up f-ing tight, but I'm a pedant.
     
  14. greenacc

    greenacc Searching for the billion

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    By torquing then to angle this also eliminates the effects of any lubricant on the thread like thread locker or misplaced slide grease. If you torque up a lubricated thread to a dry torque spec you will over torque the fastener and actually snap the bolt in some cases.
     
  15. EYY

    EYY Well-Known Member

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    Yep it's a VERY common misconception.
     
  16. lmoengnr

    lmoengnr Well-Known Member

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    F-ing tight is a great all round torque figure.:cool:
     
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  17. Geoff6666

    Geoff6666 Active Member

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    A mechanic I know used to always say tighten bolts till they snap off then back off half a turn!
     
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  18. greenacc

    greenacc Searching for the billion

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    It scares me how loose most torque specs are. When I do most bolts up by feel they always end up higher than the torque spec.
     
  19. justice4all3000

    justice4all3000 Member

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    I changed my front rotors this weekend I just cleaned the bolts with a wire brush, applied blue loctite and tightened them to spec. Years ago when I had to change the front strut top mounts the service manual asked for new bolts I spoke to the holden parts department and they told me they don't even bother to replace them!!
     

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