PT-500 Chassis Spring Tester

Some Background on Manual Testers (the old way)

When a manufacturer rates a spring, since they don't know how you will use the spring in your chassis, they typically rate the spring from "free length" (no load) to "one inch down" (ie, one inch of travel). This method of testing is also used with the "manual" spring testers available from competitors. Since these testers typically don't have a way to measure the absolute spring length they only measure relative length changes of the spring and thus can only do a "free length" type of measurement.

In addition the manual testers are cumbersome to use as the user must carefully hit the key measurement distance and must manually write down and keep track of all the measurement data.

Problems with the old way

There are several problems with this spring rating method. First of all, when you use the spring it will be traveling up and down around the loaded installed height in your chassis, not from free length. Since all springs are to some degree non-linear, the free length rate will definitely be different from the actual loaded rate in your chassis.

In addition, since the partial end coils on a spring will compress more quickly, the "free length" measurement is biased by this additional measurement error that doesn't occur if you measure the spring rate at the chassis load point.

An additional effect of the non-linearity of springs is that you typically will see a different spring rate in compression down from the installed load height than you do in extension up from the installed load height.

Thus in summary, in addition to being cumbersome to use, manual chassis spring testers don't show you what spring rates you will have in actual use for each spring in your chassis.

The advantages of the PT-500 Chassis Spring Tester

The PT-500 implements the following test method, which not only gives you much more accurate and meaningful spring rate measurements but also fully documents your spring and chassis setup for different tracks. This makes it much easier to restore a "hot setup" for a particular track.

As the first step when using the PT-500, get your car at standard race weight, ride height and tire pressures on a flat surface.

Then carefully measure and record the installed height for each spring in the chassis.

Now remove the springs and bring them to the PT-500 tester.

Starting with the Left Front (LF) spring, place it on the PT-500 tester, and compress the spring until the yellow length readout matches your measured installed height for the spring. Note that the pressure readout is now showing you exactly how much load you have on that spring at your standard race height and weight.

Now hit the Space bar on your keyboard- this will lock in that height and pressure as the standard installed height for this spring.

Now continue to compress the spring until you hear a beep from the PC and then release the pressure from the spring.

The PT-500 will then automatically measure, display and record the following information about your spring:

SPRING NUMBER 1 – LEFT FRONT

4.500 – Ride Length (Spring length at Ride Height)

1599 - Extension Spring Rate in Pounds Per Inch

1609 – Compression Spring Rate in Pounds per Inch

As shown, in addition to showing you the spring rate at the exact height that the spring is being used in the chassis, the PT-500 also displays and documents both the extension rate and compression rate for each spring. This is important, as most springs will show different rate in compression and extension. For oval track racing, on the right side of the car the compression rate is most important, while on the left side the extension rate is more important.

Now complete the measurements for the remaining springs, and with about 5 minutes of your time you have now fully measured and documented your spring setup for this chassis, as shown in the printout you can make after the measurements.

Now that you have made this first measurement of your springs, you not only have carefully measured the springs exactly how you will use them in your chassis, you have also fully documented your standard chassis setup.

As we will see in the PT-500 Demo Video, this makes it really easy to swap in higher or lower rates springs without changing the ride height or cross-weight of your chassis setup.

Unlike most of the "manual" style chassis spring testers available from other companies, the PT-500 is constructed up to critical NASCAR standards using the best industrial testing components available. The load cell in the PT-500 has an NTEP certified accuracy of 0.1% error and is designed for millions of cycles.

The PT-500 system also includes free lifetime software upgrades so as we make improvements and refinements to the system you can download software updates from this website for no charge.

Click Here to watch a Video Demo of the PT-500 in use

PT-500 Specifications and Requirements

Maximum Pressure - 5000 lbs.
Maximum Length - 17.00 inches
Basic Accuracy - 0.25 % of full scale reading

PC Requirements

The PT-500 comes with the test frame, cables, complete manual and software and is fully calibrated and ready to plug on to any PC desktop or laptop running Windows XP, Vista, 2000, NT and 98.

System connects via USB port for easy installation.

Power adapter supplied with system requires 120 Vac. European 220 Vac adapters are available upon request. Battery only adapters are also available for full mobile use.