Why a balanced setup is better than a "understeery" setup.

[Canehda]

So if I already have a coil setup with spring rates favouring the rear by only 18% would a slightly larger rear sway bar compensate for the mild spring rate difference? I currently have an OEM WRX STI rear sway bar on the car for winter mode and DD but if it helps the balance of the car and overall grip as you've shown through fast corners should I dust off the 21mm?

[CSG Mike]

Originally Posted by Canehda

So if I already have a coil setup with spring rates favouring the rear by only 18% would a slightly larger rear sway bar compensate for the mild spring rate difference? I currently have an OEM WRX STI rear sway bar on the car for winter mode and DD but if it helps the balance of the car and overall grip as you've shown through fast corners should I dust off the 21mm?

you're probably already okay as-is

[djliquidsteele]

Not sure if I missed it, but I am curious if either car had a staggered wheel/tire setup.

[CSG Mike]

Originally Posted by djliquidsteele

Not sure if I missed it, but I am curious if either car had a staggered wheel/tire setup.

Both cars have square wheels/tires.

[puma]

how about gps trace, it might just be that the green car overshot the corner so needed more steering input? How come is the blue car losing all that time on the acceleration?

[CSG Mike]

Originally Posted by puma

how about gps trace, it might just be that the green car overshot the corner so needed more steering input? How come is the blue car losing all that time on the acceleration?

If that were the case, more steering input certainly didn't increase the lateral G, which demonstrates understeer.

The particular lap in the blue car wasn't meant to be a hot lap. This is strictly to demonstrate the effect of static understeer setup versus balanced setup.

[misooscar]

Do you think the stock set up is neutral at 2.0 front camber and 1.5 neg camber with RS3s 225, 17s, on rpf1s at 7.5 in width at 250whp? (Vortech stock 9psi tune)

[themajesticone]

Does this confirm the reason behind the Fortune Auto 500 v5 being 6k/7k being a decent starting setup? Although the rates are not as high it should still provide a nice balance for the non-frequent trackster?

[Reaper]

I'm interested in the above post as well. I have rce tarmac2s en route to me with both 400 and 500 lb spring sets. This makes me want to put a set of 500's on the rear and leave 400's on the front. I'm on stock sways and 450whp.

[wparsons]

T2's with 400F/500R is similar balance to the CSG Tein SRC's in terms of front to rear spring rates, I've actually been looking at buying that setup myself.

[sittinSideways]

Originally Posted by CSG Mike

The Green car is representative of coilovers that utilize the same spring rates front and rear, or have a small stagger with the rear being larger.

The Blue car is representative of cars that utilize coilovers that have a 20-25% higher spring rate in the rear.

Hmmmm. I have Tein MonoSports, which are 8k front and 9k rear. That's less than a 20% difference. Would that put them in the green car camp?

[solidONE]

Originally Posted by CSG Mike

This is a snapshot of data being taken from two different cars at the "Sweeper" at Buttonwillow Raceway Park, which is a flat, 180 degree turn. The lines are as follows:

- GPS Speed (Speed as determined by GPS, not by the car's ECU)
- Steering angle in degrees
- Gas pedal input (in percent from none to WOT)
- Lateral acceleration as determined by GPS (Lateral G's)
- Rate of yaw, as determined by GPS (yaw rate in degrees per second)
- Lap time differential between the green and blue traces



The first thing to note, is that the green car is slower through the entire corner (graph 1); the corner is identified by the red line at the top of the graph labeled "16".

The second thing to note, is that the green car reaches peak cornering grip (graphs 4 and 5) at about 80 degrees of steering input (graph 3), whereas the blue car only requires about 60 degrees of steering input. Even with less steering input, the blue car actually maintains higher cornering grip (compare the green and blue lines on graphs 4 and 5)!! The time gained by the blue car is shown by the differential dropping in graph 6. Even though the Green car is on the throttle more through the second half of the corner, it actually makes the understeer worse, and the blue car is able to go faster!


The Green car is representative of coilovers that utilize the same spring rates front and rear, or have a small stagger with the rear being larger.

The Blue car is representative of cars that utilize coilovers that have a 20-25% higher spring rate in the rear.

Why is it that at the exit the green car is carrying a little more speed out starting from the 12500 mark? Everywhere else on that chart the green was slower or at most same speed as the blue line.

[CSG Mike]

Because the green car had a much more aggressive corner exit (look at the throttle position). Too much throttle actually resulted in needing to countersteer when going over a bump!

[solidONE]

I can see where he lifted then stabbed the steering a few degrees then lost that extra speed he had.

You should do more of these, Mike. Even better with corresponding video showing what happened.