All Linear Spring Rates

The use of an all linear spring rate, eg, very long spring (8"), with sufficient rate (325lb/in for V6s), and slightly-soft dampened (Tokico-3) provides an excellent compromise between ride & handling. The use of very long springs is unconventional and breaks the miss-perception of single "high" rates being rough. The miss-perception assumes little travel and that the stock spring-rate is 190lb/in, when in reality the anti-roll foam-stop rate (300lb/in+) is additive resulting in 490lb/in+ rates. To contrast the EU-Eibach rate is even higher than a single 500lb/in rate.

Ride - An all-linear rate combined with considerable travel avoids harshness due to sudden rate transitions and limited suspension travel. Such travel is the key as hitting a pothole at 60mph even with a 325-rate, uses up a full 2" of travel (linear potentiometer datalogging). In corners an all-linear rate shines, as potholes in the corner feel no worse than if impacted on in a straight line. Such a linear ride even in corners is something that the stock suspension can not achieve, instead crashing into the foam antiroll stops. The dampening rate is slightly under-dampened to eliminate vibration, passengers being left to enjoy the remaining taut yet unnervingly supple ride over potholes.

Handling - An all-linear rate provides for the most predictable handling possible, quite unlike other road cars and much easier to drive and co-operative when called upon in emergency maneouvres. The rate is sufficiently high to limit roll below most other spring options both at low & normal speeds, and only at very high cornering speeds will roll be greater - considering most peoples driving habits this is a reasonable compromise.

Dampening - Non-linear rates require shock absorbers to be either under-dampening when the rate is high or over-dampening when the rate is soft, with both wallow & harshness quickly resulting from poor compromises. The benefit of the reduced load on shock absorbers & linear rate is audible, with reduced rattles.

Spinal Advantage

Drivers or passengers with spinal problems will probably prefer an all linear rate, as it does not load the body with jolts from sudden rate-increases. For example, softer dampening on stock suspension can be counter productive: the higher rate is impacted on more per unit time due to the reduced dampening (ironically). A 8"-300lb/in rate will ride better but provides less road feel, and less travel so custom 8.5-300s are probably the ideal unless real coilovers are used.

Real coilovers

Real coilovers (LEDA, AVO, etc) allow the use of a tender/main spring setup (225/450lb/in) or progressive-tender/main setup (170/250/450) so with tuning a better ride (softer-initial) and handling (less roll) can be achieved. The stock anti-roll kinaesthmatic foam-stop solution follows this school of thought, but lacks tuning and later 95+ cars simply raised ride height in an awful aesthetic/handling attempt to improve ride: kin-unaesthetic stops. Many prefer all-metal spring solutions as the foam-stops vary in rate with temperature, just as wheel-rate (tire/tyre) varies similarly and the ride can be better on a warm day with with warm tyres than a cold day with cold tyres. The true ideal is a custom taper-wound spring (as used by Porsche on the 935) which has no sharp transition points to deteriorate handling or ride.

Anti-roll Bars

Anti-roll bars have a benefit for road cars in providing only an increased spring rate in corners, thus having less impact on ride than typical uprated springs. Offerings range from Eibach (Xedos6/MX6/626/PGT in Europe) with 19mm rear and uprated front bar, to Mazda Competition rear bar (16mm) and Addco rear bar (22mm), stock rear being a toothpick or 12mm in size. Eibach Europe delivery timeline on bars is several months.

Last Upload: 31st January, 2002. V1.50a
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