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Thread: Regarding the front and the rear ride frequency

  1. #1
    I am confused to that of the selection of the suspension travel of the rear and the front. so that to calculate the frequency of the rear and the front as the frequency is related to that of the suspension displacement.

  2. #2
    Roll the dices if you don't have enough time to learn such basics...

  3. #3
    Everything involving frequency is just wavelengths.

    If you have a set length of a string, say 20cm, and you need to fit it to a curve, there will be a few things that affect it. The only requirement in my example will be a constant amplitude, no progression or digression. Lay out a graph with the string laying along the +x axis and makes wave amplitudes along the Y axis.

    If you have a high amplitude, you will run out of the x axis travel shortly, leading to a low ride frequency.
    Stretching that string out so that there are many, many little waves, but a long x axis distance, then the ride frequency will be high.
    Imagine the peaks representing some arbitrary frequency value. High amplitude, less peaks, low freq.
    Low amplitude, more peaks, high frequency.

    Or you could reference a differential equations book that describes the motion of a mass-spring-damper system. The EQs check out.
    Kettering University Vehicle Dynamics
    Formula SAE 2010 - 2015
    Clean Snowmobile Powertrain 2012 - 2015

    Boogityland 2015 - Present

  4. #4
    Senior Member
    Join Date
    Mar 2008
    Brighton, MI
    Here's the easiest and best way. Just write a ...

    Sorry, I have to go...

  5. #5
    I don't have enough time to read in the depth.
    And we don't have the time to spare either.
    Cheers, Tony

  6. #6

    What don't you try to read any good vehicle dynamics book or simple Google your question before you ask this question on the forum?

    People are making fun of your post and nobody is a real winner here.
    Claude Rouelle
    OptimumG president
    Vehicle Dynamics & Race Car Engineering
    Training / Consulting / Simulation Software
    FS & FSAE design judge USA / Canada / UK / Germany / Spain / Italy / China / Brazil / Australia

  7. #7
    Boys it just very easy thing that we have
    The out of phase motion between front and rear vertical motion, caused by the time delay
    between when the front wheel and rear wheel hit the bump, is accentuated by the frequency
    difference. A result of the phase difference is pitching of the body. To reduce the pitch
    induced by hitting a bump, the rear needs to have a higher natural frequency to “catch up”
    with the front. This notion is called producing a “flat ride”, meaning that the induced body pitch from road bumps is minimized.....

    For a given wheelbase and speed, a frequency split front to rear can be calculated to minimize
    pitching of the body due to road bumps. A common split is 10 – 20% front to rear.
    The above theory was originally developed for passenger cars, where comfort takes priority
    over performance, which leads to low damping ratios, and minimum pitching over bumps.
    Race cars in general run higher damping ratios, and have a much smaller concern for comfort,
    leading to some race cars using higher front ride frequencies. The higher damping ratios will
    reduce the amount of oscillation resultant from road bumps, in return reducing the need for a
    flat ride. Damping ratios will be explained in the next tech tip in detail. A higher front ride
    frequency in a race car allows faster transient response at corner entry, less ride height
    variation on the front (the aerodynamics are usually more pitch sensitive on the front of the
    car) and allows for better rear wheel traction (for rear wheel drive cars) on corner exit. The
    ride frequency split should be chosen based on which is more important on the car you are
    racing, the track surface, the speed, pitch sensitivity, etc.......

  8. #8
    Looks like someone found the Optimum G tech tips! They're very good, take the time to read them through.

    Now that you have experienced the power of google, why don't you try and use it to answer the other question you asked? (pitch center)
    Owen Thomas
    University of Calgary FSAE, Schulich Racing

  9. #9
    Originally posted by Anuj Regmi:
    Boys it just very easy thing that we have
    Exactly. I'm glad you tried and found the answer your own.
    Do this more often.
    Sheridan Motorsports troll (2012-2014)
    Cubicle troll (2015 - God knows when)

  10. #10
    *clap clap clap*

    This is a day I never thought I would see.

    Congrats on your research.
    Kettering University Vehicle Dynamics
    Formula SAE 2010 - 2015
    Clean Snowmobile Powertrain 2012 - 2015

    Boogityland 2015 - Present

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