My way of summarizing what we all seem to agree on is this: as long as you don't go beyond certain limits, such as running out of travel and hitting a bumpstop, the question should always be what makes the car handle better (or even: what reduces lap time) and not surface phenomena, such as how many tires are on the ground. Or, given that running out of travel will always make the car handle less well and increase lap time, stay 100% focused on these.

ps. I, personally, still like to know why certain things work better than others, partly out of curiosity and partly to have an idea as to what to tweak when not happy, but I'm much more focused on outcome than I used to be. Oddly enough, I no longer compete. But this is not the first time I've gone at something bass-ackwards. And it won't be the last.

 

OK, this is a really good conversation on suspension for our cars and I am going to play devils advocate here and pose a question.


Looking at diagonal weight transfer, isn't excessive lifting of the inner real wheel a sign of major weight transfer onto the outer front wheel in a corner?


I also want to throw this car out for comparison:


http://www.vorshlag.com/forums/showthread.php?t=7924


A friend of mine here in TN bought that car and now runs it in NASA TTB/PTB here in the southeast. He came from a WRX and battled the same understeer and turn-in issues common to our platform. his first time out in this car he turned better lap times than his WRX with 100 less whp. He was floored with how well the car turned.


So this car is 3200 track weight, Mcstrut F Multi-link rear, AWD, pretty similar to what we drive. It is on 800lb front, 900lb rear springs with massive sway bars front and rear. Haven't measured them, but they are big. This is a professionally set up Grand Am ST car. So these spring rates combined with huge front and rear bars go counter to some of the arguments made in this thread.


Thoughts?

 

Hm. We seem to be back to a place where we were a day or two ago. One possible reason for the inside rear to be in the air is that the chassis is tilted both forward and to the outside (as you trail-brake into the corner) and the inside rear can't droop any more. But another possible reason is that the outside rear is highly compressed and the rear bar is lifting the inside rear off the ground. In most cases, it's a combination of the two.

 

Sure, but from that perspective you still want to minimize load transfer to the front outer wheel. Installing a bigger front bar relative to your rear bar may help keep the rear wheel down by reducing overall body roll, but in doing so you're transferring even more load on to that already overworked front tire.


First of all, I'd be very hesitant to draw comparisons between radically different cars. Suspension geometry is still going to differ extensively between the two platforms. Also, swaybar size and spring rates can't be translated from vehicle to vehicle because the motion ratio is going to make the actual wheel rates quite different.

But even still, I don't see how that setup goes against the knowledge in this thread. Like Dallas J has been saying all along, you need to focus on where your roll stiffness is coming from and in what proportions. You can increase both the front and rear bar sizes without altering the ratio of front to rear roll stiffness if you choose your bars right.

 

Seriously guys, I appreciate the back and forth. Just trying to understand everything I can about why my car behaves as it does on track and how to make it better. It's very tough down here because like in March at Road Atl, probably close to 400 cars (people scouting the track for the NASA East Coast Nationals) and outside of my friend Shaun, I am the lone Evo. And that is usually the story, so I don't have a lot of people down here to learn from on this car.


Now if you drive a C5Z, .....

 

I think you have that backwards. Having the inside rear in the air maximizes the IF/OR cross, thus minimizing the load on the outside front.

Thats not to say the OF isn't still overloaded, but its not due to the inside rear being in the air