Spring rate help?

GSS138 · 08-13-2014, 02:24 PM

Quote:

Originally Posted by j-rho

Sure every car is different, but increasing front spring rate with no other changes (increasing the ratio you mention) will make the front tires do relatively more work in a corner, which as a primary effect, shifts balance towards understeer. Your generalization is backwards of the general truth. If you want to make a case the general truth does not apply for some reason to the Z, you need to be able to explain why. You also need to be able to separate a discussion around bump handling (where shocks come heavily into play) vs. handling balance at steady-state limit cornering.

I encourage you (and anyone following along while scratching their head) to get a basic education in vehicle handling dynamics - Herb Adams, Fred Puhn, Paul Van Valkenburgh all have fairly accessible texts on the subject. A few $ for a book and a few evenings of reading, and you'll be much better equipped not only to understand what's happening with your own car, but to help others in their pursuits.

fair enough and I agree with you, but feel my point is being missed a bit, as I am not addressing over all vehicle handling dynamics, weight transfer, tires, or anything else. All I am saying is this:

There is a ratio between front and rear ride frq that will tell you if the car has a tendency to oversteer or understeer.

If you want to change that tendency-change that ratio.

To redo my example, let's go back to our OEM rates:
I am using 392 front springs, and 440 Springs (listed OEM rates I could find)
They produce a ratio of:
1.6334/1.8563 = .89

Do you not find it interesting, that using completely different spring rates, this same .89 number is produced by just about every post market spring kit within a few decimal points?

Swift Spec-R's claim 10K and 10.5K so approximately 560F 600R
they produce a ride frequency on the same car of:
2.0115/2.2427 = .89

Much stiffer springs, totally change the way the car handles, so why is that .89 ratio still popping up?

All I am saying is that .89 is not a coincidence and was put there by your car manufacturer, and by Swift, and Eibach, and by every other lowering spring I can find rates on.

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