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355 355 Caliper Bolts

Discussion in '348/355' started by kryten2001, Oct 20, 2020.

  1. kryten2001

    kryten2001 Formula Junior
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    Hello all

    Hopefully a quick and easy question for the 355 tech heads out there.

    I'm about to replace my brake calipers with a lovely brand new set I managed to acquire, and I'm also going to replace all of the fasteners at the same time. The old ones just look a bit naff.

    The original bolt (part # 174214 which supersedes part #132213) is not freely available here (Australia) and paying overseas shipping and having to wait a month for a regular bolt just doesn't seem smart.

    Does anybody have the specification of this bolt to hand? Diameter, length and thread pitch?

    Thanks chaps!
     
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  3. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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    You cannot remove one of yours and measure it?
     
  4. kryten2001

    kryten2001 Formula Junior
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    I'd rather have all the parts required before I start the job of replacing all the calipers.

    Otherwise I'll need to jack up the car, remove a wheel, remove a bolt, measure it, put the bolt back in, put the wheel back on - order the bolt, wait 2 weeks for it to come, then repeat the process to install the new calipers.

    Easier to ask the question and buy the bolts than go through all that.
     
  5. MAD828

    MAD828 Formula 3
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    Oct 8, 2011
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    The bolts have the cavallino on them so any aftermarket option wouldn’t. If you want to go that far to restore a bolt that no one will ever see maybe re plate the standard bolts.
     
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  6. kryten2001

    kryten2001 Formula Junior
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    Damn good point. Thanks for that, looks like I'm sourcing the originals.

    All that being said, all I really need to know is the size. I was going to get some black high tensile ones to replace these.

    Thanks.
     
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  8. m.stojanovic

    m.stojanovic Formula 3
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    Dec 22, 2011
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    Caliper bolts are usually non-standard overall length and non-standard lengths of threaded and unthreaded portions so it is unlikely that one could find a standard bolt that has the same mentioned lengths. Just buy original bolts, cheap and easily available.

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  9. kryten2001

    kryten2001 Formula Junior
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    Yep thanks

    Those new ones are a far cry from the nasty looking ones I've got.

    New calipers means new bolts means new brake lines means new brake discs. Just how it has to be.
     
  10. PhilB

    PhilB Formula 3
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    Why not clean your bolts and send them out for re-plating?

    I recently used a wire brush on a drill press the clean up a bunch of exhaust hardware and then had them yellow-cad plated and the results were better than original. The cost wasn't outrageous either and probably less than buying a couple of original replacement bolts.

    Of course, this is more down time for the car while the work is in progress.
     
  11. m.stojanovic

    m.stojanovic Formula 3
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    One new original bolt costs $5 at Ricambi or GBP2 at Eurospares. I think it is hardly worth going through the trouble of cleaning and plating old bolts.

    Furthermore, electroplating of high tensile bolts, especially for critical applications like brake calipers, is not recommended due to hydrogen embrittlement which can later cause premature failure of the bolt. Extract:

    "The reason for the strong opinions held by some is due to a phenomenon called hydrogen embrittlement, which leads to a drastic reduction in fatigue life and static strength. While there are a number of precautions that may be taken to lower the risk of damage from hydrogen embrittlement, ISO 4042, an international standard relating to electroplating of fasteners, states, "Complete elimination of hydrogen embrittlement cannot be assured."

    During the electroplating process, and commonly also in any earlier cleaning and descaling processes, hydrogen is evolved at the surface of the components and, particularly in the case of steels, is absorbed by the surface of the metal. Higher strength steels are particularly sensitive to hydrogen embrittlement."
     
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  13. yelcab

    yelcab F1 World Champ
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    So Miro, why don't we just remove them all, soak them in a gasoline bath, wirebrush them, paint them silver, and re-use them suckers. They are in a position that no one can see them.
     
  14. Ferrarium

    Ferrarium F1 Rookie
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    I always assumed they were Grade 8.
     
  15. Tridentecavallino

    Mar 15, 2013
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    Thomas
    Hi,
    174214 is "VITE TE M 12X1,25X 40"
     
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  16. m.stojanovic

    m.stojanovic Formula 3
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    Dec 22, 2011
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    The caliper bolts are usually metric Grade 10.9, similar to SAE (US) Grade 8. Grade 10.9 bolts (high tensile steel) in most cases come as not plated in order not to compromise their strength.

    Michell, I have not seen corroded caliper bolts, probably because they are high tensile steel and because they are kept dry by the heat from the brake. Good idea to paint them (heads only) but it would have to be high temperature paint.
     

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