911 Torsion bar to coil conversion chart • This chart was developed using actual geometric measurements.
• Note that Kw/Ks is NOT constant, since we used numerical analysis over a range from
• Kw is calculated using the actual load at the wheel center calculated with +- 1″ travel from center.
• Note nonconstant Kw/Ks
Front Rates
Torsion Kw (lb/in) Ks (lb/in)
Dia (mm) (Wheel) (Spring)
16 77 90
17 97 112
18 122 138
18.5 137 154
19 152 170
20 187 207
21 227 249
22 273 298
23 327 355

Rear Rates
Torsion Kw (lb/in) Ks (lb/in)
Dia (mm) (Wheel) (Spring)
23 107 107
24 127 127
25 149 147
26 174 171
27 202 198
28 234 229
29 269 262
30 308 300
31 351 340