MNM Scales 500 lb Compression Scale for Race Car Coil Spring & Suspension Testing
- pete8781
- Jul 29
- 3 min read
Need help planning a coil-spring test fixture or choosing the right force range? Call MNM Scales at (832) 290-3120 or email mnmscales@yahoo.com.
The MNM Scales 500 lb compression scale for race car coil spring and suspension testing gives racers, chassis shops and fabricators a way to measure the actual force a spring produces at a known compression distance. Instead of relying only on the rate printed on a spring, a controlled fixture can compare springs, check force at installed-height targets and build a force-versus-travel record using the 500 lb x 0.1 lb S-type load-cell system.
What a Spring Test Actually Measures
A coil spring resists compression with force. To evaluate spring rate, you need both force and displacement. The MNM system supplies the force measurement; a ruler, digital height gauge, caliper, linear encoder or other reliable travel measurement supplies displacement. Record force at two or more known compression positions and compare the change in force with the change in travel. A nominally linear spring should show a reasonably consistent force increase per inch through the intended working region; progressive springs intentionally change rate through travel.
This distinction matters: the scale alone is not a complete spring-rate machine because it does not measure travel. Used in a rigid fixture with an independent displacement reference, however, it becomes the force-measurement half of a useful spring test setup.
Why Test Springs That Already Have a Printed Rate?
Race teams may want to pair springs more closely than label values alone allow, confirm used springs have not changed, sort a mixed inventory, compare different brands, check force at a specific installed height, or document a setup before and after a suspension change. Measuring actual force also helps identify a mislabeled or damaged spring before it becomes a chassis-tuning mystery.
Building a Safe Coil-Spring Fixture
Compressed coil springs store substantial energy. Use a rigid frame, positive spring seats and guarding or containment appropriate to the spring. Keep the spring centered so it cannot bow out and eject from the fixture. The load cell must receive axial force without side loading. The frame, fasteners, seats and compression mechanism all need capacities comfortably above the maximum intended force; the 500 lb scale rating is not a rating for the fixture around it.
A Repeatable Spring-Test Procedure
Seat the spring with minimal preload and define a zero or reference height. Compress to the first test position, allow the fixture to settle and record force. Move to the next exact displacement and record again. Use several points through the spring’s expected working range rather than relying only on a maximum. Repeat the cycle to see whether the spring and fixture reproduce the same values. When comparing springs, use the same seats, same displacement references and same loading direction.
Using Peak Hold vs. Building a Spring Curve
Peak Hold is convenient when you want the highest force reached during a controlled compression. It is not the best tool for determining spring rate by itself because spring rate depends on force at specific travel positions. For spring curves, record force at known displacement points. Use Peak Hold as an additional check for maximum force or to catch a short peak during a dynamic fixture movement.
Suspension Components Beyond Coil Springs
Within the 500 lb range, a properly designed bench fixture can also compare bump stops, helper springs, small elastomer isolators and other suspension components whose compression force matters. Many of these parts are highly nonlinear, so multiple force-versus-displacement points are more informative than one peak number.
Frequently Asked Questions
Can this calculate spring rate automatically?
It measures force. To calculate rate, pair force readings with accurate displacement measurements and compute the force change divided by the travel change.
Is 500 lb enough for every racing spring?
No. Select a force range that stays above the maximum force you intend to apply at the deepest test displacement. Springs exceeding 500 lb at the target travel need a higher-capacity system.
Why does fixture alignment matter?
Side load can affect measurement and stress the S-beam. The spring seats and compression mechanism should keep the force centered through the load cell’s primary axis.
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