Z1 Performance

iTrader: (564)

depends what you mean by "track' - that has got to be the most overhyped word in this industry of 2006

UrbanTacticZ

iTrader: (7)

As in a serious enthusiast attending track events on a frequent basis. Not just for fun, but to tune their driving abilities.

Gsedan35

iTrader: (10)

This isn't a issue exclusive to tracking, it's a issue of providing the general public with the correct informantion so they can make informed buying decision's. Their are many owner's with progressive springs on their car's that met their needs correctly with that choice. However, for other's that appreciate what the car is about and do not wish to compromise that, they represent a poor choice. The Z is a sports car, and to that end I have devoted a lot of time providing this community with authoritive information that allow's them the ability to make more informed buying decision's regarding their suspension. Minimizing this aspect of the buying decision may work for the less informed, or those that don't care, but many are informed and equally caring.


As I have said before,......

Their is more to progressive springs regarding the compromise on performance for ride quality. Progressive rate springs are a bad idea for aggressive driving for several reasons. Soft initial compression of the springs allow the car to roll more on turn in, then the momentum built up by this roll hits the firmer part of the spring. This puts a heavier load on the outside than linear springs because the linear springs would not have allowed as much roll in the first place. And most progressive springs don't have "seamless" transitions in rate. They change rate in significant steps as active coils bottom on each other. A sudden change in spring rate, while at the traction limit, can result in a nasty slide. And further still, a progressive spring has two or more rates on one spring, right, that's what makes them progressive. ...let's assume that for the first three coils, the rates are 250lbs per inch and that for the next two inches, the rate is 350 lbs per inch. Therefore, when at rest, suspension will be compressed on the 250lbs spring section, and the next inch of movement will be in the 350 lb per inch range.

Now let's use the same scenario......a corner is entered and the outside spring is compressed one inch and the inside spring is extended .75 inch...rememeber the rates!

Now you encounter a bump in the corner...and since you are currently using the outside spring at a rate of 350 lbs per inch and the inside spring rate of 250 lb per inch... and the suspension is compressed the additional two inches....what happens to the spring rates? Since they differ, the chassis rotates around the roll axis... and the vehicle attitude changes/rotates differently than when in steady state cornering! Its motion becomes slightly skewed since to offset the bump deflection each spring must work through a different spring rate! If you were to then hit another bump, the attitude would change again...and so forth. All of these things of course would not happen with linear springs.

Progressive springs can be made to work in very limited conditions where the parameteres are well known, like a specific road course where telemetry is constantly giving feedback to help select the right rates.

Z1 Performance

iTrader: (564)

While I agree in principal with what G35sedan posts most of the time (I think we come from similarly experienced backgrounds as far as suspension), let's not forget that there are plenty of performance cars that use progressive springs as stock, which often will literally run circles around even a modded Z.

Yes, progressive springs exist because they are an excecise of compromise. The fact remains, that like ALL parts you buy for your car, some companies do things better than others, and it does take a bit of research by the buyer, should they care, to determine the best overal item for their car and their scenario.