Quote:
Originally Posted by GSS138
I am dividing front/back, you could just as easily divide rear/back and see it inverse. All that matters is the number of units it is away from 1.
Just like 90 is 90% of 100, and 100 is basically 110% of 90(with some rounding problems). Pretty sure we are on same page.
What I am getting at is that if you mess with that ratio, it induces one or the other-oversteer or understeer. If you think the car understeers, you can reduce that understeer by 10%, or you can increase oversteer by 10% the same way-by increasing or decreasing that ratio. The factory sets it a particular way to make the car safe(.80-.89 generally, or 1.1-1.9 inversely). Almost across the board unless you buy a Ferrari, factory race car, or something else I can not afford.
The post market spring kits aren't reducing understeer or increasing oversteer with their rates(none that I can find and will post all the ones I know if you want). They are just increasing the ride rate(not to be confused with ride frequency). Increasing ride rate is great, and yes will reduce some understeer naturally on a car where the suspension is too soft overall. That is not what I am talking about at all.
An experienced track driver of a car instinctively knows, that a ratio of .89 (as I describe it) is not "fast". That's why the "performance coilover" solutions invert that number and come in at ~1.11(or .89 of OEM understeer the way you are describing). It feels fast! And by all accounts is fast. It's a major improvement over the understeer induced slosh bucket designed by the oem setup engineers.
The higher wheel rates alone make the driver feel faster, take the slosh out of the ride, and they also help prevent suspension geometry problems by eating up some shock travel and lowering CG. It's honestly a brilliant solution at a very good price.
So at that point , unless someone has a question, I give up too.  |
Not trying to argue about it man, I sincerely hope this discussion in some way helps somebody learn a little more of the basics of things.
You're hung up on this ratio that is just one small part of the picture, and your understanding of it is backwards. If you want, try putting 2000lb. springs in the rear of your car, and 500lb. in the front - the ratio will be way less than .89, which according to your equation, would make the car understeer like crazy. Go try it (not on the street! somewhere safe!) and report back how the car handles - bet you'll find it oversteers like crazy.
The ratio is but one variable. Adding front camber arms to an otherwise stock Z will give the front more grip, which will make it more oversteer-y - but the ratio would still be .89. Putting wider and stickier wheels/tires up front only would increase front grip and make it more oversteer-y, without changing the ratio. Putting on front aero devices to give the front more grip at speed would make it more oversteer-y, without changing the ratio. And on and on... As soon as you start making any changes to a car, including lowering, a lot of the assumptions that went into the factory handling balance go out the window, and the ratio of front to rear ride frequencies really becomes meaningless. What matters is that the car fits the needs of the owner/driver for what they want - whether it's lowest laptimes, good performance while retaining street manners, or whatever.
On some car, in some conditions - possibly even a 370z, a f:r ride frequency of .89 might just be perfect - but that value is arrived at as a result of having optimized all the aspects of the chassis/suspension and its setup that matter - not because anyone was trying to hit (or avoid) that value.
