Motorbike brakes on a car?

Thread in 'Technical Questions' started by MJG, Feb 9, 2012.

  1. MJG

    MJG Active Member

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    So my latest idea of saving weight is the brakes.... I'm already planning on running small cheap wilwood calipers on poverty model solid brakes, but the discs are still 5kg each and calipers are 1kg.

    Has anybody ever heard of motorbike brakes being used on a car? Aside from the fact their centre bit of the disc doesn't have a car-friendly fitment, you can get 4 or 6 pot radial mounted calipers which are tiny, and 6mm thick discs that are only slightly bigger than the pad contact patch.

    These are designed to slow a 200kg bike from 150mph+ with the tweak of a finger so when drift cars only use the brakes to make minor adjustments on a smaller diameter road wheel, does it matter that the car weighs 4 times as much as a bike?

    I imagine my enemies are brake fade and pads being destroyed, but my most hardcore braking manoeuvre would be to stamp on them for like 1-2 seconds at 100mph, or to ease on them round a corner to keep the speed down. Are they really going to cook for that use? I want them to work, obviously, but their feel and sharpness is worth more than their outright power IMO.

    What are your thoughts?
     
  2. mrsilvia

    mrsilvia Member

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    I think the bigges enemy will be slowin 900kg down from 60 on a thin disk? Ain't there like a minimum thickness a normal car disk can be on MOT? Im not an expert but I think your a crack ed m8!
    175 quids gets you a cheap floaty disk on flebay
     
  3. mat_91

    mat_91 Member

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    hmm i can see your point mike even being just a pure drift car but what if your following someone and they spin and you need to stop fast what if you cant smash all your hard work gone because your brakes arent man enough i think just live with standard ones and save weight else were after all brakes are important
     
  4. mrsilvia

    mrsilvia Member

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    Shit man... U shuld use bog roll to strap you in isstead of a harness an a paper plate for steerin wheel, air's lighter than brake fluid too! Lol. Y skimp on safety man!!!
     
  5. bessell

    bessell Member

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    My thoughts are its worth a try if you have the fab skills the biggest thing to worry about would be warping them also your bmc will be huge compared to the bike one so just sneezeing at the pedal may cause an emergency stop lol.
     
  6. mrsilvia

    mrsilvia Member

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    Wot if he kills a marshal or driver on tha track!!
     
  7. Rossc0

    Rossc0 Diesel Skidder

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    init! dis is a forum, nt a txt

    If it works, it would be awesome, but at the same time like has been said already, it could be better to save weight elsewhere if possible
     
  8. kam

    kam I've touched Chris Parry

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    Check out the FD handbrake setups, they use a really thin disc to get temps up quick. Good weight reduction too, not that it really matters with an LS7...

    [​IMG]

    Wouldn't like a bike brake as a front footbrake though.
     
  9. mrsilvia

    mrsilvia Member

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    Or an English lesson?
     
  10. Damianator

    Damianator Member

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    I like your "thinking outside the box" the only way to find out is with tests but you would need the space to do it safely.
    It could be a break through but could also not work I say worth a try. :thumbs:

    If you do decide to try it let us all know how it goes as very intrested. ;)
     
  11. MJG

    MJG Active Member

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    I've seen lightweight solid discs, but this is taking it a step further. I agree it could be too weak and get hot too quick, but thats why I asked the internet rather than just trying it straight off! I also know the BMC will be excessive but I'll be running a pedal box anyway so can adjust that to suit.

    As for the "save weight elsewhere" statements, I appreciate the safety concerns but without a technical explanation
    I will not give them responses any credit. "cut springs are fine until you kill a marshall" haha.

    I'm sure in the history of the world, some idiot must've tried motorbike brakes on a kit car or something!?


    If nobody has any experience then I'm happy to give it a go, but no harm in asking eh. I'll keep everybody posted if it comes to it.
     
    #11 MJG, Feb 9, 2012
    Last edited: Feb 9, 2012
  12. kam

    kam I've touched Chris Parry

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    They're not just "car" solid disc though, I'd imagine the above is what you'll come out with baring in mind you're going to have to use the bell from a car fitted to a bike disc.

    That setup would be fine on the front too I bet, I'd just rather some proper brakes there!
     
  13. Andy_F

    Andy_F S13+S15=S28?

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    A guy I know has done this on a rat drag Civic he's made. Tiny thin bike brakes on the front, no brakes on the back, rear suspension totally stripped away to really nothing other than a wheel and a coilover. I'll try and grab some pictures, doesn't look too bad - he turned a stock brake disc down on a lathe to a single layer thin enough for a bike caliper, then made his own adaptor to bolt the caliper on. He reckons he's saving about 15-20 kilos in total with this on the front.

    I can see the benefits on a drag car which only really needs the brakes once, and not particularly hard, but is it really a good idea on a normal car? I'll ask him how effective they are when I see him next week.
     
  14. proseal

    proseal Member

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    Guys are all fucking bitches mike :). I say try it, buxton is an excellent testing ground for this sort of thing. My design boss makes custom motorbike parts on the side. And he can make any shape and thickness disc you'd need.
     
    #14 proseal, Feb 9, 2012
    Last edited: Feb 9, 2012
  15. retro-ed

    retro-ed Flicks 'n' Kicks

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    Mike,

    I will probably be doing this to the back of the escort soon.. I will be using a set of bike front radial mount 4 pots and either a 106 gti disc turned down to 7mm thick (Std is 8 I think) or a pair of 220mm bike ones I have in my draw :)

    Getting the caliper in the wheel can be a pain due to where the bleed nipple and inlet are but this is dependant on caliper size.

    For the rear of a light car they should be more than adequate. I dont think people realise how much of a pasting they are designed for on bikes!
     
  16. mrsilvia

    mrsilvia Member

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    If I may interject good sir, i am sure there must be a mathematical equation to calculate minimum thickness of a brake disc, taking into account specific heat/latent heat capacities and shear stress etc acting upon the disc/rotor thus enabling you to calculate the optimum lightness/thickness ratio and use the correct metal alloy?
     
  17. Alex B

    Alex B Active Member

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    Only got experience with my GSXR brakes, but there's no way I'd trust them to stop a car, Suzuki decided the bike needs 3 discs to slow a 166kg, (plus rider of course ;-) ), bike down, so doubt they'd work for long slowing a car down.

    Biggest issues would be the amount of heat generated would warp them first heavy use, also, subject to how you converted them onto a car, they're held together with big rivets and again not designed to stop that much weight.

    Alex B
     
  18. kam

    kam I've touched Chris Parry

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    We're talking pure drift car here I presume?

    1 emergency stop if needed from sub 100mph (Max), or adjustments mid-drift.
    I think they'd be fine.
     
  19. mrsilvia

    mrsilvia Member

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  20. retro-ed

    retro-ed Flicks 'n' Kicks

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    For the back of a car like Mike is planning the corner weights at the rear would only be about 120kg a side under a hard decel.. I have no doubt if they were on the front they would fry but for the back it is not really that much of a bonkers idea.

    The bike discs are also far better quality than cast Iron car jobbies. You would be supprised how much effort it takes to really fuck up a well designed bike disc.
     

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