System Includes: Variable Speed Controls, High Load Scales (2200lbs/Wheel), Single Load Cell (15" Scale Pads), Integrates with Data Acquisition Systems, On-Line Video Training, Manual Input Wheel Load & Position Graphing Calculator
System Benefits: Fully Upgradeable, Portable, Wheel Base & Width Adjustable, Works with all Chassis Types
How to Use Your Pull Down Fixture for Performance Gains
- Use the fixture to establish your “track height”. This is the desired attitude (travel & roll) of the chassis on the track. Be sure to allow for tire roll clearance. 3/8” at the cross member & ¾” at the nose.
- Adjust your spring/bump stop combination to reach the needed wheel loads at your track height. This is where you will set your bump stop timing, choose primary spring rates, bump stop rates and shims. During this process, you will watch wheel load curves and make sure you are not “spiking the load” causing grip loss.
- The first two steps will eliminate chassis over traveling and track contact, causing grip loss.
- Now that you know where the car will travel to, you can adjust dynamic balance. This is where the sway bar comes in. Move sway bar load (more roll/Stiffer Bar/softer RF) will increase dynamic cross. Less bar load will decrease cross.
- Next, adjust the dynamic bite through acceleration while maximizing total forward traction. (You need the acceleration kit for this.) Adjust trailing arm angles, top link positioning, etc.
- Through these five steps, you can test any combination of set-ups. You will see how they change your travel, know what travel adjustments to make and see how they affect dynamic balance. Through testing, you will know what your optimum dynamic balance is for each track.
- Different style tracks will produce different wheel loads. You will determine the wheel load for each track by testing, measuring chassis travel and then pulling the car down to that travel. Once you have the wheel loads recorded for each track, you can test set-ups for each track all year long. You will notice higher wheel loads in qualifying and be able to adjust travels for that easily.
- Next you will study your dynamic wheel positions. You will measure bump steer on both front wheels. Your will measure the dynamic camber and caster. You will measure caster jacking to see the affect it has on your chassis’ balance through steer. You will measure rear steer and lateral rear end movement. You will measure the contact patch alignment change from static to track height. Knowing these measurements, you will be able to make handling and grip adjustments accurately without affecting other areas of the chassis.
- You will watch for suspension binds as you travel the chassis under load and correct them.
- You will find bent items (spindles, axle tubes, control arms, etc.) and correct them.
- You will ensure that the chassis moves freely under load and repeats itself.
- Finally, you will compare set-ups and other chassis to identify unique characteristics that can be reproduced.
- Ultimately, the pull down fixture will allow you to fine tune set-ups and develop new set-ups for an advantage. It will eliminate time consuming errors at the track, costing you valuable practice time. It will help uncover chassis problems that cause performance loss far quicker than visual methods. And it will increase your knowledge of the chassis and suspension tremendously without excessive test days at the track.
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