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Tech: What's the Spring Rate of my Torsion Bars? #torsionbarhondas Content Inside!

1984-87 Honda Civic/CRX and 1986-89 Acura Integra models came with a unique torsion-bar front suspension. Because of the non-conventional nature of a torsion bar as compared to a spring, people at times become lost on what various bars' diameters equate to what would be conventional spring rates. This is an important figure for determining the balance of the car and for tuning the dampers.

Between the various diameters and lengths of bars available, we were a bit lost on it ourselves, but a little poking around led us to Sway-Away's website. As some may know, Sway-Away is one of the foremost torsion-bar producers having even produced bars for said Hondas at one point in history. We knew this convenient calculator was something we could trust!

On the page there you will find the science behind the torsion bar wheel rate calculation. You'll also see that the effective wheel rate is the same as the spring rate taken at the end of the control arm, or what is actually the lever on which the wheel's movement acts.

You can play with it all you like, but we have taken the liberty of making a quick chart for fast approximate reference. Some of our dimensions are approximate but the spring rates should be accurate within about 5-10% and that's really pretty good for our purposes!


  • LCA stands for "lower control arm." Since people tune both Integras and Civic/CRX models, and sometimes Civic/CRX people put the longer Integra lower arms in their car to increase camber, we include both here. We approximate a 13.5" length on the Civic/CRX and 14.5" on the Integra, from the center of the torsion bar to the end of the ball joint.
  • All rates are in pounds per inch of travel (lb/in), but we have a lb/in to kgf/mm charge just below.
  • Not all these torsion bar diameters are actually available, but we are listing them anyway since any of them technically could be made or exist.
  • The bar length will impact the wheel rate, too. The 24.3" bar is the length of CRX and many Civic bars. Some Civics have a bar that is about 1/3" shorter, but the rate change is faily minor so we have omitted it to keep the chart simpler. The Mugen bars that were made long ago were shorter than the Civic/CRX ones, with an overall length of just under 22.5". These would give a highest rate per diameter, and being the more compact bar would have the least weight (no surprise that the Mugen bar would be the ideal for performance yeilding the most rate-per-weight!).


  Civic/CRX LCA Integra LCA
22.5" 24.3" 25.7" 22.5" 24.3" 25.7"
19mm 97 84 80 84 73 70
20mm 120 109 102 103 95 89
21mm 145 133 125 126 114 108
22mm 175 159 150 151 139 130
23mm 209 190 179 181 165 155
24mm 247 225 212 214 195 184
25mm 291 265 250 252 230 217
26mm 340 310 293 295 269 253
27mm 396 361 340 343 313 295
28mm 458 417 393 397 362 341
29mm 527 480 452 457 416 392
30mm 603 550 518 523 477 449
31mm 687 626 591 596 543 512

We work on Japanese cars at Heeltoe here, and oftentimes it becomes necessary to work in both lbs/in and kgf/mm (that's kilogram of force per millimeter). They are different ways of saying the same thing about a spring's rate, but we've offered this handy conversion chart for you to know the equivalents. This info is pulled from's Standardized Spring chart.

lb/in kgf/mm
112 2.0
140 2.5
168 3.0
196 3.5
224 4.0
252 4.5
280 5.0
336 6.0
392 7.0
448 8.0
504 9.0
560 10.0
672 12.0
784 14.0
896 16.0
1008 18.0
1120 20.0


Please feel free to leave any commentary or calls for correction below! And never forget that Heeltoe is always in your corner, aiming to provide the best and most accurate info we can to help you tune your car!

About the Author

Marcus di Sabella Marcus is the founder of Heeltoe Automotive. He's been working with cars (mostly Honda cars) since 1996, and has been providing enthusiasts with excellent products, services, and web experiences since 2002. He's been published in Honda Tuning, and holds a degree in Engineering Technology.


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