SCCA Solo C Street Discussion

[Wepeel]

So if you do the math for total wheel rates in roll for the BRZ, and reduce it to natural frequencies, in completely stock form the BRZ has a front:rear natural frequency bias of 1.24 (Front Roll NF / Rear Roll NF). Adding a Strano front bar shifts that to 1.55 (more understeer). Keeping everything stock and removing the rear bar shifts it to 1.60, so a little more under-steery than the stock with the Strano bar but not too much so. Balance wise I would think it would be pretty similar but obviously the chassis will be moving around more.

Removing the rear bar will remove about 79 lb/in of rate from the rear wheels in roll and reduces overall roll stiffness by about 13%.

[dsgerbc]

Not sure what's minimal, but anyway.

On a really bumpy road it could help - sure. But I'd rather not drive on those lots where disconnecting RSB helps. In the rain? You mean for putting down power? Maybe (I'm not sure it's gonna help much short of standing water or 1st gear in this car), but you're still better off with a larger FSB and disconnected RSB if you want minimal load transfer in the rear.

I just don't see the point of lowering overall grip to take care of mild oversteer. Just mess with tire pressures to give rear a bit more grip relative to the front.

[mrazny]

Originally Posted by dsgerbc

Not sure what's minimal, but anyway.

On a really bumpy road it could help - sure. But I'd rather not drive on those lots where disconnecting RSB helps. In the rain? You mean for putting down power? Maybe (I'm not sure it's gonna help much short of standing water or 1st gear in this car), but you're still better off with a larger FSB and disconnected RSB if you want minimal load transfer in the rear.

I just don't see the point of lowering overall grip to take care of mild oversteer. Just mess with tire pressures to give rear a bit more grip relative to the front.

Bolded the part that's not allowed in Street class for the skimmers that might not have read the whole conversation.

[7thgear]

Originally Posted by dsgerbc

Not sure what's minimal, but anyway.

because physics?

weight transfer is dictated by center of gravity, track width, and weight.

nothing else

during roll, the center of gravity shifts slightly but not enough to really impact the general state of things.

control of roll in production cars is primarily there to reduce dynamic alignment changes and keep the tire in perfect angle to the road.

http://www.motoiq.com/MagazineArticl...-transfer.aspx

[itzmik3]

[ame="https://www.youtube.com/watch?v=pivMquF2Sqw&list=UUfrcGo4iul6xqAvyWGlLR4w"]CSCC - Championship 3/23/14 - YouTube[/ame]

video from this weekend's racing.

this was the closest I have been able to get to Jeff Stuart in the 370z (.478)

i had a couple sections that i definitely could be cleaned up, but overall very happy with the result

[brz7400]

Originally Posted by itzmik3

video from this weekend's racing.

this was the closest I have been able to get to Jeff Stuart in the 370z (.478)

i had a couple sections that i definitely could be cleaned up, but overall very happy with the result

Thanx for spanking me by over 4 secs, otherwise, an awesome drive!
You were actually faster than Jeff after run#2...

[JB86'd]

Originally Posted by brz7400

Thanx for spanking me by over 4 secs, otherwise, an awesome drive!
You were actually faster than Jeff after run#2...

Hey don't feel bad, @itzmik3 spanked me by 10 seconds! Nice run Mike. In my defense it was my first autocross and fully stock tires and suspension hahah. El Toro was a blast, I think I've been bitten.

75.093. I need to work on my hand position, and a lot of other things!

[ame]http://youtu.be/_ygZFemsEyU[/ame]

[itzmik3]

Originally Posted by brz7400

Thanx for spanking me by over 4 secs, otherwise, an awesome drive!
You were actually faster than Jeff after run#2...

hahhaa thanks thanks.
yeah i spoke with jeff after all the runs were over and he said he was actually a little worried after my 2nd run. sadly from there i was left in the dust.

[itzmik3]

Originally Posted by JB86'd

Hey don't feel bad, @itzmik3 spanked me by 10 seconds! Nice run Mike. In my defense it was my first autocross and fully stock tires and suspension hahah. El Toro was a blast, I think I've been bitten.

75.093. I need to work on my hand position, and a lot of other things!

sorry i couldn't give you a ride on saturday.
it was super hectic dialing in the C-Street car and doing shakedown runs in Max's STX BRZ
maybe at the next practice

[JB86'd]

Originally Posted by itzmik3

sorry i couldn't give you a ride on saturday.
it was super hectic dialing in the C-Street car and doing shakedown runs in Max's STX BRZ
maybe at the next practice

No worries at all man! That'd be great. I think I'll try and run in the next Saturday practice also.

[dsgerbc]

Originally Posted by 7thgear

because physics?

weight transfer is dictated by center of gravity, track width, and weight.

nothing else

during roll, the center of gravity shifts slightly but not enough to really impact the general state of things.

Weight transfer is roughly fixed (but does change a bit due to roll). Total weight transfer can be split (in other words which parts of the car react to more of Earth's reaction force) into one part where higher suspension compression counteracts part of the higher weight on that corner, and a second part due to suspension links' tension. Neither is minimal.

But that's off-topic basically. Like I said, I see not point in reducing total roll stiffness of the car for regular autox.

[3essess]

the main reason autoxers unhook the rsb is to help keep the inside rear wheel planted when applying power out of turns - helps the torsen work

[dsgerbc]

Originally Posted by 3essess

the main reason autoxers unhook the rsb is to help keep the inside rear wheel planted when applying power out of turns - helps the torsen work

Fat FSB does the exact same thing. Like I said, if you're lifting inside rear with the fattest FSB, then I can see the point.
I might be wrong, but I don't believe the rear inside lift is a problem in this car in C Street. It probably is in STX.

[7thgear]

Originally Posted by dsgerbc

Fat FSB does the exact same thing. Like I said, if you're lifting inside rear with the fattest FSB, then I can see the point.
I might be wrong, but I don't believe the rear inside lift is a problem in this car in C Street. It probably is in STX.

making one end stiffer vs completly unhooking something are entirely different things

no swaybar = 100% independence, the inside tire can droop all it wants without any interference from the loaded tire