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Technical Caliper behind axle centerline?

Discussion in 'The Hokey Ass Message Board' started by RMR&C, Mar 19, 2021.

  1. Jay McDonald
    Joined: Apr 6, 2020
    Posts: 66

    Jay McDonald

    I have been working in motorsports full time since 1986, I have never met anyone who could explain why it would work that way, it comes up every couple of years
     
  2. Mimilan
    Joined: Jun 13, 2019
    Posts: 942

    Mimilan
    Member

    No for 2 reasons,
    1: Because there is no rocker equalizer that allows the tandem spring set up to "float" [or rock]
    2: Lift on the trailer suspension is caused by rotational torque at the axle centreline transfering to the frame [via the leafs]
    Calipers basically transfer rotational movement of the rotor into rotational torque of the avle/housing that it is attached to.[it makes no difference where the calliper is mounted.

    A simple analogy is to imagine a trailing arm.
    Now if the caliper was placed at the top or at the bottom. The forces at the point of friction are either forward [top] or rearward [bottom]
    Yet it places the same rotational torque around the axle centreline. Which tries to lift the wheel off the ground [or lower the front pivot] on a trailing arm.
     
    RMR&C likes this.
  3. 1971BB427
    Joined: Mar 6, 2010
    Posts: 7,045

    1971BB427
    Member
    from Oregon

    I heard years ago from a friend who owned a brake relining business that calipers were first put on the backside to keep them out of harm's way. If anything got to bouncing down the highway and hit under the car it would likely not hit the calipers on the backside.
     
    Budget36 likes this.
  4. tub1
    Joined: May 29, 2010
    Posts: 517

    tub1
    Member
    from tasmania

    I like them on the back of spindles so you can't see the dam things as I like the look off drum brakes
     
  5. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 341

    HotRodWorks
    Alliance Vendor

    I'm having a hard time visualizing that. If we look at a simple system like a beam axle, and remove the suspension parts (spring and wishbone), the brake caliper clamping on the spinning rotor would cause the axle to rotate. The wish bones are what stop it from rotating.
    Can you explain, through some type of simple diagram, how the location of the caliper clamping on the rotor would cause a different reaction from the suspension parts?
    I'd like to better understand that.
     
    Last edited: Mar 22, 2021
    RMR&C likes this.
  6. Jay McDonald
    Joined: Apr 6, 2020
    Posts: 66

    Jay McDonald

    I'm dying to hear that myself
     
  7. Jay McDonald
    Joined: Apr 6, 2020
    Posts: 66

    Jay McDonald

    not looking like I jumped to quickly, went from backward thinking to crickets
     
  8. Tow Truck Tom
    Joined: Jul 3, 2018
    Posts: 163

    Tow Truck Tom
    Member
    from Clayton DE

    Youse guys is hurtin my brains. I need ta take a nap. ( I like mine up front! )
     
  9. grumpy65
    Joined: Dec 19, 2017
    Posts: 925

    grumpy65

    Hey Jay, I am also waiting for @Mike VV to expand on his theory. If you go back and read his first post again, he describes the action he talks about using the terms 'minimal' and 'very little'. I personally can't see how caliper location could possibly affect tire load to any noticable degree, but I am happy to concede that there may be some very small, insignificant forces created. I am also happy to concede that @Mike VV probably has better qualifications regarding this than I do. Therefore, I will not jump too early. I will remain open minded until such time as I am suitably convinced one way or the other.........:rolleyes:
     
  10. Jay McDonald
    Joined: Apr 6, 2020
    Posts: 66

    Jay McDonald

    I'm not going to dwell on this any longer but there used to be a bunch of really sharp cookies on the hamb and it was the best resource on the net but most of them are long gone because it is frustrating when someone jumps in and says backward thinking with nothing to back it up.
     
  11. grumpy65
    Joined: Dec 19, 2017
    Posts: 925

    grumpy65

    Yes, I do see your point, but we are here for a discussion, not an inquisition...........
    We will not all be correct about things all the time, but passive discussion will always be a better option than calling people out on there interpretations. Mike may expand on his view, or he may not. Either way, it's all good............;)
     
  12. Tow Truck Tom
    Joined: Jul 3, 2018
    Posts: 163

    Tow Truck Tom
    Member
    from Clayton DE

    Science, Physical Science says for every action there is an equal and opposite reaction. A vehicle traveling forward ( with front mounted caliper ) can make use of extra pressure against the tire tread. Consider the spindle to be a fulcrum. The the wheel, a lever, will create a downforce against the tread patch.
     
  13. grumpy65
    Joined: Dec 19, 2017
    Posts: 925

    grumpy65

    So when the caliper/brake pads clamp onto the rotor and generate a force via friction, surely the force is shared between caliper and rotor - one pushing up, the other pushing down. Same deal whether calipers are leading or trailing. Force shared in both directions, therefore cancelling each other out.

    Like you stated using Newton's Third Law (quoted above), you need to consider both the action and the reaction...;)
    A leading caliper is being pushed down by the rotor, but the rotor is equally being pushed up by the caliper.....
    Equal and opposite...........
     
    HotRodWorks likes this.
  14. lake_harley
    Joined: Jun 4, 2017
    Posts: 1,534

    lake_harley
    Member

    My opinion is quite simple.....torque is torque. Unless the brake caliper is on a floater (rear suspension) and can apply upward or downward pressure directly to the frame through a separate link, it doesn't matter if the caliper is on the front or back side. With floated brakes you can make the car squat or resist squatting while braking.

    A similar argument has raged on and on as well and that is that "pinion angle" (nose of pinion pointing down toward front of car) increases forward bite. It's just torque.

    Lynn
     

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