Rear spring rate

[small change]

The IC location does not affect weight transfer. Weight transfer is determined by the acceleration, total car weight, wheelbase, and center of gravity height, with a limiting value equal to the static front end weight.

IC location does affect the car attitude during launch. In other words, an IC location which yields less than 100% anti-squat will cause the rear of the car to squat during launch; a value over 100%, rise.

i agree,but the IC will affect weight transfer if the car squats or rises through the position the center of gravity height in relation to the rear axel[something which i think can be used to your advantage when dealing with weight that cant be moved].

in relation to spring rates,if the car can be set to 100% anti squat the springs do nothing[or very little]under acceleration and therefore only need to hold the car at ride height when not under acceleration.

[BillyShope]

The IC location does not affect weight transfer. Weight transfer is determined by the acceleration, total car weight, wheelbase, and center of gravity height, with a limiting value equal to the static front end weight.

IC location does affect the car attitude during launch. In other words, an IC location which yields less than 100% anti-squat will cause the rear of the car to squat during launch; a value over 100%, rise.

i agree,but the IC will affect weight transfer if the car squats or rises through the position the center of gravity height in relation to the rear axel[something which i think can be used to your advantage when dealing with weight that cant be moved].

This is true, of course, but I was responding to a statement by Bubstr ("The thing that transfers weight is the difference between your center of gravity and the instant center."), which posits an invalid relationship between CG and IC. You could have said that IC location can affect acceleration and thereby change the weight transfer, which would also be true.

in relation to spring rates,if the car can be set to 100% anti squat the springs do nothing[or very little]under acceleration and therefore only need to hold the car at ride height when not under acceleration.

Again, very true. Many dragracers place undue emphasis on rear spring and shock selection when, as you correctly point out, the rear springs and shocks are merely going along for the ride when the car is operating at or near 100% anti-squat.

[thetech]

Hey Bill; I was just pointing out that, a weight change without a spring change will also change some other important frequency's.................

Spacer's may, or may not, improve a given set-up -- the "length" of the track. Not just the launch....................... Olley also had "his" perspective on anti-squat.................. It was also called the anti-roll characterisics of an IFS, and those same formulae work just as well, in the anti-squat mode.

1). Wheelbase change.
2). Potential designed IC movement.
3). Potential fixed value of anti-squat.

Kind of a big picture thingy...................... Many don't take alot of this stuff into consideration though! Too much eye candy on display..............

[BillyShope]

Hey Bill; I was just pointing out that, a weight change without a spring change will also change some other important frequency's.................

I suppose it could be argued that a change might contribute to the excitation of tire shake, but such excitation is usually caused by torsional vibration of the tire and not by Z axis motion. Again, I would consider the change under consideration to have inconsequential effects.

Olley also had "his" perspective on anti-squat.................. It was also called the anti-roll characterisics of an IFS, and those same formulae work just as well, in the anti-squat mode.

I have the collection of Olley's notes ("Chassis Design" by Milliken and Milliken) and I know of no instance where Olley forced a lateral loading analysis into an analysis of loading during X axis acceleration, nor do I know of an instance where anti-squat was discussed during an analysis of lateral loading. (I confess, however, that I have not read every word of that tome, so I might be mistaken.) While you are correct in your realization that a strong kinematic similarity exists between the two situations (especially when compared to a 4WD vehicle in forward traction) and that, again, this realization isn't common among non-engineers, I don't believe it profitable to take it any further. Because of "jacking" problems, it would always be necessary that the transverse equivalent of "anti-squat" have very low values, whereas dragracers are often interested in values exceeding 100%.

[thetech]

Come now! Do we really need to differentiate between the engineer and the non-engineer. Kind of a fixation on academia and the non-academic, don't you think? An accurate descriptive of that condition, may be relayed upon request........................................ (a medicinal recommendation may also be included)!

Anti's don't care which direction/vector is being used. It's all in the lay-out.......... His wording is very subtle (clear and foundation laying)(Gillespie validates/Milliken verifies)(GM profited from), -- but it will require an entire read, of Milliken's "Olley" publication (sae also has some of his paper submissions). And; it will require code writing, to make it apparent...............

I have written the code -- seen the magic -- and know what it means................................ Olley was apparently, a "very" smart/protective man! I understand that his work was considered "Top Secret" by the company (I also believe he had his own personal/mental classifications as well)("engineering envy" and all that), back in the day! And; credit MUST be given, where credit is due.....................

Before we get lost in one of your linkage jousting match's. K^2 rig (equalization of pitch/bounce frequency's),.............. pertaining to rear spring choice of this thread (some refer to it generically as a 20-30% softer front). It's about "ride"............, then "roll", then "squat", then "dive", etc.........

You really must "rethink" HIS "work".................... Some are "discovering", for the very first time.

"Rethinking" is apparent in Cup/Nationwide/ARCA down to many of the top late model teams............. The most aggressive (anti-roll advocates), being the "dirt" late model teams, some even using progressive/regressive anti's, related to SLA changes. Profitable/non-insignificant/consequential enough for some...$$$...

Immitation "is" the greatest compliment/realization! Isn't it, Bill?

It's a big picture "thingy".\/