Brembo Caliper Bolts

Discussion in 'Ducati General Discussion' started by CarloL, Sep 7, 2019.

  1. Want to tidy up the calipers with new Stainless bolts , will regular M8X40 cap bolts do or do you need the low profile head

    5 gbp vs 30 gbp for the low profile head

    Normal SS caps

    [​IMG]


    Low profile head

    [​IMG]
     
  2. Can do but i used Ti myself...
     
  3. What do they cost each? I will likely change all mine this winter...
     
  4. Not that expensive - you can get them on ebay - loads of people sell them...
     
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  5. I thought about changing out for SS but always thought about the tensile strength of stainless....
    Would they shear under high load of braking force
     
  6. Carlo, there are many grades of stainless and most that are used for replacement fasteners are not suited to safety critical applications like the calliper bolts due stainless generally having lower tensile strength. Many people that use them are unaware that the materials are relatively soft with lower strength and should not be torqued to the same torque numbers as the originals (the same issues affect some titanium bolts), to do so risks breaking them or them shearing during heavy breaking. The same people think twice about replacing con rod bolts with alternatives but don't worry about what could be a much more dangerous failure than a dropped rod.
    If you can find out what the spec and tensile strength is of the oem ones by all means use equivalent alternatives of whatever material, otherwise it is safest to just replace them with new or clean good oem ones. Don't fall for the "they work ok on my bike" argument, they will all work ok until they break and using weaker bolts incorrectly torqued makes that risk much higher than it needs to be.
    BTW, Calliper bolts are marked in the factory manual torque tables with a safety critical indication which generally means more accurate torque settings required
     
    #6 Denzil the Ducati, Sep 7, 2019
    Last edited: Sep 7, 2019
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  7. Denzil , do you know whats in the manual , required tensile strength

    Probolt Stainless

    An identical replacement to the original only with great rust resistance! They fit most early Brembo calipers and can be torqued to manufacturers' original settings.
    • Density 8030kg/m3 (501lb/ft3)
    • Young's Modulus 193GPa (28 x 106psi)
    • Yield Strength260MPa (37.7 x 103)
    • Ultimate Tensile Strength570MPa (82.7 x 103 psi)
    • Compressive Strength260MPa (37.7 x 103 psi)
    • Shear Modulus78GPa (11.3 x 106 psi)
    • Ductility40% elongation at break +
    • Minimum value allowed by ASTMA240
    • Poisson's Ratio0.27
    • Hardness95 Rockwell B+
    • Maximum value allowed by ASTMA240
    • Strength-to-Weight Ratio32.4 kNm/kg
    • Stiffness-to-Weight Ratio24.0 Mnm/kg
     
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  8. Carlo, it does not specify any strength or materials data for the original bolts
     
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  9. Carlo, To give an indication of the various grades and tensile strength, most better quality automotive fasteners are 8.8 grade high tensile steel with yield strength of around 800N/mm2, high tensile bolts like the calliper ones are 10.9 or 12.9 grade which have a yield strength of over 1000N/mm2. The strongest stainless fasteners easily available is A4-80 which has a yield strength of around 800N/mm2 or equivalent to 8.8 steel. The fasteners listed above are only rated at 260N/mm2. You can see why the correct torque setting for the weaker bolts is important, to use the same figure as used for the higher strength ones could easily cause them to break
     
    #9 Denzil the Ducati, Sep 7, 2019
    Last edited: Sep 8, 2019
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  10. Used arp stainless bolts for high tensile applications which have a tensile strength of 170,000 psi which equates to 1170N/mm2. They’re are an American company and offer range in imperial or metric - you would need to check available metric range and pitch for your application . They fully list all the torque settings for their bolts. For me the important supply was imperial so I could manufacture 12 point stainless nuts for the barrel base for my old triumph. Buy a 12 point bolt - cut the head of and tap imperial to form a nut.
     
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  11. https://www.westfieldfasteners.co.uk/A4-80_ScrewBolt_HexHd_M10_THRpart.html
    If anyone wants to buy stainless bolts in A4-80, here is one useful source.

    Many sellers do not specify what they mean by "stainless steel", in which case they are selling A2.
     
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  12. Buy pretty much all my fasteners from Westfield especially torx head and reasonably priced. Good company to deal with.
     
  13. I would have thought the last place to buy any safety critical bolts is Ebay.

    Most large OEM's have a very strict traceability scheme for fasteners, right back to the original batch of material at the mill.
     
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  14. I have ebay Ti ones in 3 bikes. My bike my choice.
    They come from China, the same people who make most of the stuff that we have these days, even iphones.
     
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  15. Oooh, where do you get those?
     
  16. I have a story about Chinese bolts that were used as after market by the US military on helicopters.

    But yes, you're bike.
     
  17. I have a story about an OEM bike manufacturer called Ducati using shit bolts made from cheese :bucktooth:
     
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  18. My Chinese levers are fine, used them on all my bikes.
     
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  19. I have chopsticks from China, they are very good :D
    Take note of what Denzil has said and make your choice, Denzil speaks the facts so you know what you are doing whatever you decide
     
  20. set of four caliper bolts for the Monster m900 come in a £4.48 from Ducati

    Probably cheaper and safer to swap out new OE bolts every few years
     
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