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NEW BRAKE CONCEPT...

Discussion in 'Technical Q&A' started by need4speed, Apr 8, 2004.

  1. need4speed

    need4speed Formula 3

    Nov 3, 2003
    1,597
    Pacific Palisades
    I came across this article on a new brake concept but I can't seem to find it now. I was wondering if anyone else read about this.

    The concept is instead of going bigger to increase surface area, use 2 small rotors and 2 small calipers, as in a sandwich.

    Based on a recent post that explained why bigger diameter rotors suck up horsepower, this seems like a better way to go. And with so many aftermarket brake systems being lighter than stock, doubling of rotor and calipers might still end up lighter than a stock brake system. Thus not adding to unsprung weight.

    Any comments?
     
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  3. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,965
    The twilight zone
    Full Name:
    The Butcher
    I've seen attempts at this on motorcycles. The problem is always that the rotor needs to float to make it workand thing bind. It is also a problem to get air to both.
     
  4. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,004
    Kansas
    Full Name:
    Sean F
    Unsprung weight is unsprung weight. What does it matter if it's one disc or two? Either way you have to spin the same rotational mass to get the stopping power you want.
     
  5. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,556
    MO
    Yes, good cooling can mean almost as much difference as upgraded calipers rotors, and doing such with this setup can be difficult.
     
  6. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,556
    MO
    Sean it is rotational. More energy (read hp) is needed to move a disk with a 355 then with a 273 size disk..even if they are the same weight.
     
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  8. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
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    Rob Schermerhorn
    Right on! It's called Moment of Inertia (MOI) and is a property of any rotating object. The closer the mass is the center of rotation, the less MOI.

    This is why heavy, large diameter wheels will cost power to the pavement, why light flywheels increase engine acceleration characteristics.

    As for brakes, I've also read about this concept, and believe it has merit, though cost at this time is greater than traditional solutions, and in typical engineering/ business environments, cost drives the design when there's profit involved.

    One requires mass to absorb and dissipate the energy of deceleration. True, that a larger effective diameter increases brake torque. Everything in engineering is a compromise.


    Best regards,

    Rob Schermerhorn
     
  9. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,662
    Pendanic mode = ON

    One requires mass to absorb the energy. One requires air to disipate the energy.

    Pendanic mode = OFF

    Two smaller disks can have lower rotational inertia, and more mass, at the same time; for the same pad sweep area.
     
  10. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,004
    Kansas
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    Sean F
    But is it easier to spin two small flywheels, or one larger one?

    You're correct, it's all a compromise and I'd think the benefits of two discs would not be worth the effort required to make it work or the F1 teams would be doing as such (unless prohibited by rule). Also, I'm having trouble seeing a real advantage b/c of the physics involed with dealing with two systems at each wheel vs. one.
     
  11. chrismorse

    chrismorse Formula 3

    Feb 16, 2004
    2,149
    way north california
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    chris morse
    I am leaning toward the biggest diameter disc for increased brake torque and greating coling area. I think sloan got it right with 18 inch wheels and 332 discs, (if i recall correctly).
    In our efforts to drive the car as fast as possible, I try to make the systems as linear and ergonomic as possible to maximize my meager tallents; lower profile tires to reduce the slip angle, plastic bushings to reduce compliance, light flywheels and internal components to make revs happen now, lower center of gravity to reduce weight transfer ect, ect all to make the car easier to drive.
    Sorry, I digress, Double discs would have greater surface area, (assuming using vented discs, possible packaging problems, huge cost and developement time.
    I still keep coming back to the bigger discs and their "leverage", I cannot help but think that they would have a much better feel and be more easy to controll. Less caloper flex, lower line pressure, easier to duct air to.
    Let's look at the inertia problem. How much does a 14 or 15 inch disc weigh above the stock unit?? I have no idea, I am loking for some numbers.
    My guess is that a Victoracer or other z rated radial will be about as light as can be reliably put on the road.
    This leaves the wheels. If we look at reducing the inertia as much as possible, I am guessing that we will come up with a forged center section and a spun aluminum rim section. I do not know, I have been away from racing for a long while.
    I think we will see that low weight/inertia and cost are exponentially expensive.
    BTW, I am thinking about 17-18 inch rims for the 308 - suggestions??

    Dazed and confused,
    chris
     
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  13. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,556
    MO
  14. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
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    Rob Schermerhorn
    Assuming mass is equivalent, the smaller diameter, even if two parts, requires less energy to accelerate.


    Nice catch Mitch. I admire attention to detail.

    Rob

    BTW, chrismorse:

    A tire that operates effectively at larger slip angles will yield greater feedback to the less experienced driver. In general, novice drivers like low tire pressures, higher aspect ratio (sidewall height taller), brand new sticker tires, and bias-ply vs. higher pressures, cured and heat-cycled radial tires. The former allows larger slip angles to develop before "letting go" or reduction in grip from sliding too much. Ultimately not as fast, but may be a faster set-up for a less experienced driver.
     
  15. chrismorse

    chrismorse Formula 3

    Feb 16, 2004
    2,149
    way north california
    Full Name:
    chris morse
    Rob, There is a lot to be said for tire choice that displays a broad range of feel, certainly easier to drive. On my "beater work" truck, I have run two sets of bridgestone 195/50 so3, (on 7x15 mag rims) and am currently running Goodyear F-1s, (the best summer max perf tires /tire rack), cockpit adj air springs, good shocks and poly supported F/R bars and a $4000 engine just to haul my fanny and concrete to the job site. got 25 years hard autoxing, massive lust for high speed sideways driving and am looking to find the right combination for my 308 - sticky-floppy- low pressure tires are not going to get the job done.
    I perhaps mispoke, (sorry for the diatribe), I am looking for mechanical solutions to enhance driver feel and controll, linearity of sensory input and output. hence tighter suspension bushings, wider rims for lowe slip angle, lower profile tires for more of the same and more direct response, tighter springs and shocks, ditto, lower c.g. = free points.
    The most fun you can have with your cloths on is to throttle steer the auto, at a good rate of speed, in and out of the turn, ahead of the competition.
    regards, chris
     

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