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  1. #1
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    Composite Pistons?!!! EEW EEW EEW!

    in the new Magura Marta Mags? that just sounds like a bad idea to me... Injection moulded caliper pistons... they're plastic right? i don't care how little heat they transfer, i'll take steel any day.

    Anybody agree?

  2. #2
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    Quote Originally Posted by AlexJK
    in the new Magura Marta Mags? that just sounds like a bad idea to me... Injection moulded caliper pistons... they're plastic right? i don't care how little heat they transfer, i'll take steel any day.

    Anybody agree?

    They have been making composite pistons in automotive brakes for years and they work fine. They weigh quite a bit less and the heat doesn't seem to bother them at all. There is a fair bit more heat in a car brake than a bike brake to boot.

    I don't think they will have any problems with them.
    I'm not very smart, but I can lift heavy things

  3. #3
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    really?? this is the first i've heard of them, especially for automotive use... just doesn't seem safe to me... i just can't imagine...

  4. #4
    ...In the meantime.
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    What brakes are you running now? Unless they're Hopes chances are they're a composite piston of some type...Providing they're hydraulic discs of some sort.

  5. #5
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    i was using bb5s but i just got Juicy 5s. Do they have composite pistons? that would explain the black color and cheap price for a rebuild kit... it just seems REALLY weird to me!

  6. #6
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    composite pistons have been in use, reliably, forever. wouldnt worry about it for a second.

  7. #7
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    wow... i woulda never thought that they would use plastic in one of the hottest parts of the brake system!

  8. #8
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    you should check out how far plastic has come since the 70's

    they've made small engines out of plastic.. something like 3000 degree combustion temps, and something silly like 100k psi of pressure.

    i think the corvette 5.7L engines used resin pistons.. or resin coated, or phenolic or some composite.

  9. #9
    Meh.
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    Avid, Hayes, etc all use "plastic" pistons. Phenolic pistons have been used in car brake calipers for some time as well. It transfers less heat.

    I do not recall the LS1 or LS6 ever having plastic pistons. It had a composite intake manifold. Otherwise they're all aluminum. The LS6 in the z06 had sodium filled valves and lighter pistons... though not composite.

    http://en.wikipedia.org/wiki/GM_LS_engine

  10. #10
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    hahaha, if they ever put plastic pistons in any corvette, i would know about it, i'm a vette nut, they use the composite intake though. Which i'm no fan of because it doesn't like boost pressure too much (i <3 Kenne Bell)

    the new ZR1 uses carbon ceramic graphite or the likes for the rotors

  11. #11
    Meh.
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    The composite intake mani is more than robust enough for NA applications. And as a stock piece, it's well thought out. It's light and resists heat soak. Boosted LSx motors are just ill.

  12. #12
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    What about this Ashima brake ??

    From http://reviews.mtbr.com/interbike/as...nterbike-2009/

    "The PCB or Pancake Brake has no pistons, and instead operates using a diaphragm seal. The design is very simple, lightweight, and has very thin calipers (25mm). The piston less design, gives an excellent response, simpler manufacturing, and has an equivalent area of a 20mm piston. Wayne has another brake in the works,the 4 pot APV (Ashima Power Valve System). The PCB just became a Design Award Winner at the Eurobike Show, congratulations to Ashima."

  13. #13
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    off topic

    Quote Originally Posted by HotzKiss
    What about this Ashima brake ??

    From http://reviews.mtbr.com/interbike/as...nterbike-2009/
    So
    I take it that they are not self centering?
    Diaphragm + many flexural cycles + many heat cycles = rupture?
    Last edited by gte819s; 09-30-2009 at 06:44 AM.

  14. #14
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    see... some companies are pushing it way too far IMO



    and i wouldn't trust that intake mainfold with a supercharger (at high boost, i know the ZR1 is blown) i mean, if that BOV opens up a second too late... BOOOOOMMM and the blower is 30 feet in the air and theres a gigantic hole in the hood. On a lot of monster trucks/dragsters/pullers you have to strap them down to keep them from shooting off into a crowd. And that's with a fairly thick aluminum intake.

  15. #15
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    Quote Originally Posted by gte819s
    I take it that they are not self centering?
    How many brakes are?

    As far as the topic goes; I think that use in MTB brakes is an excellent application of composits/plastics. Hope brakes have used phenolic pistons exclusively for the last five or six years.

    What use is a philosopher who doesn't hurt anybody's feelings? -
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  16. #16
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    Quote Originally Posted by AlexJK
    see... some companies are pushing it way too far IMO



    and i wouldn't trust that intake mainfold with a supercharger (at high boost, i know the ZR1 is blown) i mean, if that BOV opens up a second too late... BOOOOOMMM and the blower is 30 feet in the air and theres a gigantic hole in the hood. On a lot of monster trucks/dragsters/pullers you have to strap them down to keep them from shooting off into a crowd. And that's with a fairly thick aluminum intake.
    no bov... bpv yes... bov no.

  17. #17
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    oh whatever, they both releive boost

  18. #18
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    Quote Originally Posted by SteveUK
    How many brakes are?
    Right. I was actually thinking of the ability to compensate for wear but stated self centering. The diaphragm looks fixed. Unless it can move outward or there is an adjustment (man/auto) at the lever, the throw will increase with wear. I cant imagine that the diaphragm can flex as much as a piston can move.


    However it looks interesting as the diaphragm can solve the issues with lazy pistons, leaky piston seals, etc.

  19. #19
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    Besides, I don't think phenolics are plastic - aren't they a thermoset resin and very hard, not plastic or thermoplastic? You can heat it and heat it and heat it and it will not deform until it burns, afaik.
    "It looks flexy"

  20. #20
    Meh.
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    Quote Originally Posted by AlexJK
    see... some companies are pushing it way too far IMO



    and i wouldn't trust that intake mainfold with a supercharger (at high boost, i know the ZR1 is blown) i mean, if that BOV opens up a second too late... BOOOOOMMM and the blower is 30 feet in the air and theres a gigantic hole in the hood. On a lot of monster trucks/dragsters/pullers you have to strap them down to keep them from shooting off into a crowd. And that's with a fairly thick aluminum intake.
    With the exception of the ZR1 and the new Vauxhall VXR8 Bathurst S, the LSx motors are NOT forced induction from the factory. So why would they bother with something else? The composite intake mani works great for this application. It's light, resists heat, is easy to produce. It doesn't have to cope with boost. That's like saying, high compression ratios are bad and I don't trust them for any application because they are not suitable for forced induction. I'm going to make a car. It's not supercharged or turbo charged... but just in case somebody down the line wants to... why I don't make my compression ratio ridiculously low to make it boost friendly but run inproperly now. I'll also make sure all my spark tables are optimized for the turbo that is not equipped. I'll be sure the throttle body is far too large for this NA setup. Oh, I suppose I'll fit a turbo mani now as well, save them trouble later. Sorry... that's not how things usually work.

    Do you know how a BOV or BPV works? The idea is that when the throttle body closes, the pressurized air is abruptly stopped and then tries to force its way back through the compressor. BOV or BPV prevents this from happening. BOV is connected to the intake mani with a vacuum hose. When the throttle is closed, manifold vacuum without pressure develops and the BOV is sucked open. The BPV vents the air back to before the turbo. The BOV vents to atmosphere. Unless the spring rate is too stiff, the valve is too big, or the unit is faulty, there's no reason a BOV would open "too late."

    Unless you go with a centrifugal charger, the blower sits right on top. The LS1 MagnaCharger TVS replaces the intake mani. If you go with a centrifugal charger or a turbo, there are plenty of aluminum replacements.


  21. #21
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    i do beiliev i'm getting cars mixed up in my head... i think i just had a confusion between the ZR1, ZO6, and the GT500KR (freaking embarrassed now...)
    yeah i know how BOVs and BPVs work, my dad taught me that when i was very young (like... 7yo i think)

    and my neighbor's drag jeep is set up way differently than that motor... it has the blower mounted on upper left side of the engine and uses a standard intake manifold, carb is Pre-blower (i think).

    It's set up funny cause he did it on the cheap using a used eaton blower and a kit he got off of ebay for connecting it like that. only cost him like $500
    but he also only gained 3-4 HP after many tuning runs on the dyno. i think it needs bigger valves.


    This is why i only ride 2-stroke ATVs and dirtbikes (yeah i know, Blah blah blah enviornment blah blah Al Gore blah blah polution blah blah blah... i care, but i like to ride )

  22. #22
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    isn't most any component a 'composite'?
    Honestly... ahh I give up

  23. #23
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    Quote Originally Posted by gticlay
    Besides, I don't think phenolics are plastic - aren't they a thermoset resin and very hard, not plastic or thermoplastic? You can heat it and heat it and heat it and it will not deform until it burns, afaik.
    Phenolics are a type of plastic...

    From Wikidpedia here and here and a separate source here.

    Plastic is the general common term for a wide range of synthetic or semisynthetic organic amorphous solid materials suitable for the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce costs.

    The word derives from the Greek πλαστικός (plastikos) meaning fit for molding, and πλαστός (plastos) meaning molded. It refers to their malleability, or plasticity during manufacture, that allows them to be cast, pressed, or extruded into an enormous variety of shapes—such as films, fibers, plates, tubes, bottles, boxes, and much more.


    Phenolic plastics have been largely replaced by cheaper and less brittle plastics, but they are still used in applications requiring its insulating and heat-resistant properties. For example, some electronic circuit boards are made of sheets of paper or cloth impregnated with phenolic resin.

    Phenolic sheets, rods and tubes are produced in a wide variety of grades under various brand names. The most common grades of industrial phenolic are Canvas, Linen and Paper.


    Please excse the C&P!

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