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  1. cibachrome

    LandRover Death wobble

    But these are just patches to a systematic problem of positive feedback in the suspension geometry activated by tire and road inputs.
  2. cibachrome

    LandRover Death wobble

    Shimming may quiet it down simply because this adds some friction in the steer/ride mode. A higher flow rate pump can work as would a more responsive steering valve if power steering. The fundamental problem is the tierod slope in front view. Change the height of the steer arm ball off the...
  3. cibachrome

    Suspension Factors Behind Mustang S550 Crashes in Parking Lot Exit Scenarios

    Take your decent bicycle model, set the wheelbase to 0.0+ and take it for a spin. I said decent, not the Milliken madness, it has to have tire Mz inclusion. Then watch pro rally driving on YouTube.
  4. cibachrome

    Suspension Factors Behind Mustang S550 Crashes in Parking Lot Exit Scenarios

    These drivers are using tire pressure and aftermarket wheels + low traction tires to achieve their burnout and drifting performances. (It's pretty obvious to those of us in the business). They obviously have disabled the traction control and likely the traction control would believe it knows...
  5. cibachrome

    Layoffs 2024-2025 ??

    I'd add 1 more item. If you have stayed on the forefront of your company's technology base, you become the subject matter expert that they can not afford to loose. Stay out of all management positions to stay in the 'game' in the trenches. You might even be asked to hire in as a consultant if...
  6. cibachrome

    Strut tower bar preload: tension or compression?

    Try that in a submarine heading to 500 meters.
  7. cibachrome

    Dynomometer

    From the supplier graphs, I'd say that you should run the motor at 1400 - 1500 rpm to maximize fuel economy (the engine can recover from load spikes easily because it's torque gain is very high there. But it won't be 700 h.p. because the rpm is below the h.p. line.
  8. cibachrome

    Strut tower bar preload: tension or compression?

    The towers move together, so a top brace might only see a small moment but little strain. Had to prove this with a strain gauged bar and an analog meter on the dash of a test car. Very little signal but noticeable effect on the on-center gain. What's needed is a 'bridge' to keep the towers...
  9. cibachrome

    Strut tower bar preload: tension or compression?

    It makes no difference. Can you guess why ? (A common mistake)
  10. cibachrome

    Chassis Stiffness and Suspension Tuning for Track Cars (i.e. Miata, Cayman, 911)

    Don't make the assumption that a chassis 'torsional stiffness' is a constant that you might see in a home ladder. It can be quite a staircase function and also depends on whether the chassis is 'dressed' or not. Plus, how would you rate your kitchen table if three legs sit nicely on the floor...
  11. cibachrome

    Tire performance versus lateral load and camber.

    Here's a sample of Mx brand characteristics at the same Fz load for a commonly used size. Yes the pair of tires needs to be taken into account during turning, but you can see what could happen to your braking/traction ratings if you chose the wrong one... Did I mention that a rotation...
  12. cibachrome

    Tire performance versus lateral load and camber.

    As a general statement, more camber generates more lateral force. You need the characteristics of YOUR tires to know what the gain is. While you may imagine that the center of vertical load is in the center of the wheel, it is most likely not. As a result, there is an offsetting moment (Mx)...
  13. cibachrome

    Determining Maximum Acceptable Play in Bushings / Spherical Bearings for a Hobbyist Track Car Build?

    Fear not, but just because your Miata has about 50% weight distribution (which make for great advertising), it has gobs of front compliance steer, both lateral force and aligning moment. Front roll steer is 5%. The Mz steer slope (1.13 deg/100 Nm) is more than twice what a 'normal' everyday...
  14. cibachrome

    Determining Maximum Acceptable Play in Bushings / Spherical Bearings for a Hobbyist Track Car Build?

    A 2002 Miata with 205/45-R16 Bridgestones churned out about 250 - 300 lbs/deg. But you might be on race slicks that are FAR stronger.
  15. cibachrome

    Determining Maximum Acceptable Play in Bushings / Spherical Bearings for a Hobbyist Track Car Build?

    Zero in all steering parts. Some vertical in suspension but the noise with bother you. Rear suspension: no acceptable free-play. The only allowed deadspace is with tapered roller bearings because you want them to live. This all hangs on how fast you want to go. But, consider this: A tire...
  16. cibachrome

    What are the industry-standard metrics for quantifying oversteer, understeer, and neutral handling?

    Actually the values don't change that much from say, 1000 miles to 30,000 miles on the car. This is by design not luck or accident. Same with weight distribution from Driver only to GVW. Based on ride height changes, tire durability, and steering stiffness performance specs. But the first set...
  17. cibachrome

    What are the industry-standard metrics for quantifying oversteer, understeer, and neutral handling?

    They are all bad for pretty much the same reason: Transient response in the kill-zone.
  18. cibachrome

    What are the industry-standard metrics for quantifying oversteer, understeer, and neutral handling?

    Very simple. An Understeer/Oversteer/Neutral Steer function is the first partial derivative of the average steered road wheels minus the Ackermann gradient with respect to steady state lateral acceleration (by definition). Expressed as units of degrees per g. Degrees of the Reference steer...
  19. cibachrome

    Benefits of body roll for street performance cars?

    Adding the chassis structural compliance to the mix via the high contribution Normal Modes gets you pretty darn good correlation and satisfactory functions of load. This includes hysteresis. This was done using NASTRAN at the time to do a free-free normal modes of the dressed chassis, sorting...
  20. cibachrome

    Benefits of body roll for street performance cars?

    1) Just mu opinion, but for your 'sports' cars, roll steer is a bandaid to fix deficiencies caused by adherence to lore about weight distribution, tire sizes, total roll stiffness, etc. It's the worst one because the car rolls by convolution: You steer to get Ay, then the Ay activates the...

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