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Thread: Goodguys Gazette

  1. #21
    Senior Member Funding Member Morris's Avatar
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    What they are after is shock settings.....we’ve all gone thru the set up, tire & chassis phase....but the shocks are a real secret to handling at the actual race track.....including the braking.....so getting the shocks set and knowing what to do when the track changes is the difference between the men and the boys.....that has been around for quite a while....I’m sure you’ve heard of a team coming off the trailer....and going fast from the get-go.....the less adjustment made at the track....the better....

  2. #22
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    Quote Originally Posted by Silverback View Post
    I agree Dan. I watched another couple videos also and what they did not tell you is what information they received and what they did with it. I understand the basics but I'm sure there is a lot more to it.
    As Morris said it is about the shocks. If you look at a tires characteristics (vertical load vs lateral load capability) you will see that it goes up almost linearly until it peaks then as vertical load goes up lateral capability falls off.
    Drivers (good ones) can feel this in the steering when near the limit because steering efforts go down slightly so they know more lateral force is not available. The idea is to tune the shocks so that the tire is not subjected to momentary loads that push it into the area where its capability diminishes. Once you go beyond that limiting factor it does not come back as quickly as it falls off. For example: if the drivers is operating near that limit and the tire/wheel encounters a bump the load on the tire spikes and you lose traction. A good shock will avoid that spike in load by allowing the tire/wheel to move up and keep the load on it relatively constant. That is the whole key to handling don't over or under load the contact patch. Years ago when I was with Ford we put the Jaguar XJ 220 on our 7 post rig and helped them set up shocks for Laguna Seca. They picked up 2 seconds a lap with that help. Our main Goodguys competitors have tube frame Corvettes that weigh the same as a Cobra, they also have Warren Johnson built LS engines that make big power so they are very formidable. They hired an ex NASCAR engineer to fly in to each event and help with data acquisition and chassis tuning. He is the one that talked them into going on the rig to tune their shocks. We have known for quite some time that they had too much rebound from watching their outside car videos but of course never shared that with them. Now I am concerned that they will be even faster since they will undoubtedly fix that problem. Think about it this way, shocks can make tire loading more consistent in cornering , acceleration, braking and over irregularities which increases available grip and that leads to lower lap times. We run JRI shocks which is now owned by Ray Evernham, it was started by Jeff Ryan after Penske sold his shock company. We like them because they have a huge range of adjustment and very low hysteresis. They can get you in big trouble with that big adjustment range but on the plus side you don't have to re-valve either every time you change springs. Hysteresis has to do with how quickly they pick up load again after a change in direction. Another example: When the track is very slippery shocks can be adjusted to reduce loading to a manageable level by reducing bump and rebound forces because available traction has been reduced. This would normally result in more body pitch and roll but because traction is reduced it does not. This is all greatly simplified but it gives you an idea of why shock tuning is critical.

    Sorry: back to the question, the rig has load cells that measure the actual force on the contact patch during all the pitch and bump motions so it can show you instantly if a shock adjustment
    helped to maintain a more constant load at the contact patch.
    Last edited by CSX3170; 03-27-2020 at 10:25 AM.

  3. #23
    GROUCHY FUC***G OLD APE Funding Member Silverback's Avatar
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    Where do the spring rates factor into this. I would have to assume that one influences the other. And roll bar stiffness would also be part of it.

    Am I correct in assuming that you can optimize the shocks for a certain spring rate and roll bar stiffness, but if you change either one of those then the shock settings may no longer be optimized.

  4. #24
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    Not always, there is a range where you can run with a particular set up and adjust more for track conditions than anything else. Springs and bars have to do with constants shocks deal with transients. A high spring rate calls for more rebound generally and vice versa, if you have a steady state issue you adjust springs and bars for balance if you have a transition problem IE Turn-in probably a shock adjustment. Everything you change will have positive and negative effects, the challenge is to minimize the negative.

  5. #25
    Senior Member dominik's Avatar
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    Cool rig. I assume they actually record the movements of their every car component on the track in question and simulate such a lap with the car on the rig. Just need to add weight for downforce and push sideways for G-forces. Add a wind tunnel and you're all set. Like a cyclist who can cycle the Tour de France in his lounge. Sort of... :-)

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