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

[celica73]

Being that the cars aren't on the same tires, the comparison is pretty much void anyhow. Nice try, but the scientific method does apply to most comparisons like this, and you have drawn conclusions where they can't reliably be drawn.

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!

then take your foot off the throttle and let the front tires work? You romp on the gas mid turn and expect the front end to grip. Weight transfer to the rear takes load off the front and makes the front end work worse, not better.

Steering angles were similar entering the turn, though it looks like you turn in later with the blue trace. The blue trace shows some notable rotation (big spike in the yaw rate). Rotation = lose, not neutral. After that, I'd expect less steering was needed, as all the turning was done on corner entry (admittedly good place to do it). Similarly, I notice the steering angles are identical until you jam on the throttle in the green trace (10,550 mark) after that the understeer is in full effect. Maybe that's an ill timed heel-toe downshift (we don't have that info on the graph) - but who does that mid turn, that should be the blip at 10,300.

You appear to totally short shift the blue car, why? Different tires can have a huge impact on handling balance (I've done that experiment), setups can vary dramatically with compound changes/sidewall stiffness, etc. It's fancy data, but with 0.09 seconds delta between the cars (which evaporates shortly after corner exit) I think we might need to put away the jump to conclusions mat.

[continuecrushing]

wheres the line for the car that was sideways the whole time?!

But awesome info+time spent putting this together and explaining

I seriously LOL at all the "racers" who contradict what @CSG Mike says because the conditions were not perfect/exactly the same. I'm pretty confident he's done enough testing to know what the hell he's talking about. However, with that said, the alignment of the moon was different between laps, therefore the information he presented is completely useless/not applicable to anything.

There are VERY FEW people who put forth the effort, time and knowledge to help the racing community that @CSG Mike does.

[nikitopo]

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.

Great study! This pretty much justifies why the oem springs have a higher rate in the rear. I was checking for sometime the springs of different manufacturers and it looked to me that same rates front and rear would not give an optimal result.

[CSG Mike]

Originally Posted by celica73

Being that the cars aren't on the same tires, the comparison is pretty much void anyhow. Nice try, but the scientific method does apply to most comparisons like this, and you have drawn conclusions where they can't reliably be drawn.

then take your foot off the throttle and let the front tires work? You romp on the gas mid turn and expect the front end to grip. Weight transfer to the rear takes load off the front and makes the front end work worse, not better.

Steering angles were similar entering the turn, though it looks like you turn in later with the blue trace. The blue trace shows some notable rotation (big spike in the yaw rate). Rotation = lose, not neutral. After that, I'd expect less steering was needed, as all the turning was done on corner entry (admittedly good place to do it). Similarly, I notice the steering angles are identical until you jam on the throttle in the green trace (10,550 mark) after that the understeer is in full effect. Maybe that's an ill timed heel-toe downshift (we don't have that info on the graph) - but who does that mid turn, that should be the blip at 10,300.

You appear to totally short shift the blue car, why? Different tires can have a huge impact on handling balance (I've done that experiment), setups can vary dramatically with compound changes/sidewall stiffness, etc. It's fancy data, but with 0.09 seconds delta between the cars (which evaporates shortly after corner exit) I think we might need to put away the jump to conclusions mat.

At some point, a line has to be drawn for a reasonable comparison.

I'd approximate the grip difference between the tires on the two cars is about 20% of the grip difference between a fresh street tire and a heat cycled street tire of the same model.

Are you going to point out that the cars had different wheels too? Or different levels of fuel in the tank? Or that ambient temperatures aren't identical and a 2mph cross wind was present for one, and the angle of the sun affected tire grip?

This isn't the "best" laps between the setups being compared, but rather hand picked laps for the purpose of comparison.

Take the data for what you will. It's not perfect, and never will be perfect.

*edit*

Re: stomping on the throttle: has it occured to you that the car is still accelerating, in spite of the understeer? That's why that green lap is faster exiting

[CSG Mike]

@celica73

For you:

[celica73]

Originally Posted by CSG Mike

Are you going to point out that the cars had different wheels too? Or different levels of fuel in the tank? Or that ambient temperatures aren't identical and a 2mph cross wind was present for one, and the angle of the sun affected tire grip?

This isn't the "best" laps between the setups being compared, but rather hand picked laps for the purpose of comparison.

Take the data for what you will. It's not perfect, and never will be perfect.

Actually, I was going to ask about fuel in the tank, and a passenger in the left seat (a passenger will make a noticeable difference in these cars).

I don't disagree that you have made a comparison between two laps. I'd stop there though, because you might as well be comparing a granny smith to a golden delicious. They are both apples, neither are red.

I'll take your word that the "blue" car was more pleasant to drive, but you don't need data to tell you that.

[CSG Mike]

Originally Posted by Shutter

wheres the line for the car that was sideways the whole time?!

But awesome info+time spent putting this together and explaining

I'd love to do that... but I generally don't get intentionally sideways unless asked to by the car's owner, and neither of the cars are mine...

The rate of yaw is more stable drifting, but the actual lateral G is "off" due to the slip angle; you actually have to interpolate it from lateral and longitudinal forces, using the actual yaw angle of the car relative to the corner.

That being said, if we actually DID interpolate the data in that fashion, the blue car in the example would actually have a little bit more lateral G, albeit a few percent which would barely show on the graph.

[celica73]

New data shows the downshift nicely. Thanks.

[CSG Mike]

Originally Posted by celica73

New data shows the downshift nicely. Thanks.

You can actually see me intentionally using the downshift to try to upset the rear, but the car is so front biased that it didn't actually step out. It did result, however, in achieving the highest peak lateral G momentarily when the rear was loaded more from the pseudo clutch kick.

If you want to see any other data in that corner, let me know and I'll be more than happy to post it.

[Kostamojen]

I would love to see driver seat videos of this.

[CSG Mike]

Originally Posted by Kostamojen

I would love to see driver seat videos of this.

They'd actually be really boring; the only thing you'd really be able to compare is how much the steering wheel is turned to go through the same corner.

I'll see if I can borrow a gopro or two the next time I do something like this.

[cdrazic93]

interesting, @CSG Mike, have you had any seat time with the higher end 1 ways? like MCS, JRZ, or Ohlins? or are they more glorified really nice street dampers? I have a feeling that to get competant track times, the adjustability needs to be for compression too, atleast.

[CSG Mike]

Originally Posted by cdrazic93

interesting, @CSG Mike, have you had any seat time with the higher end 1 ways? like MCS, JRZ, or Ohlins? or are they more glorified really nice street dampers? I have a feeling that to get competant track times, the adjustability needs to be for compression too, atleast.

Only a limited amount, and you're correct, the 1-ways are all geared toward inexperienced drivers, since the experienced drivers who know what they want won't be getting a one way.

[cdrazic93]

Originally Posted by CSG Mike

Only a limited amount, and you're correct, the 1-ways are all geared toward inexperienced drivers, since the experienced drivers who know what they want won't be getting a one way.

interesting. Ill keep that in mind when looking at future upgrades, mainly keep it to springs. Once Ive completed some HPDE instruction and gotten more...legal seat time, then I will take a look at some double adjustables.