Thundermoose

They look to be too fat as well. Ideally, there show be almost not time from full throttle to brakes, and then braking should be very sharp. FWIW, I am working on both of those elements.

Frank 993 C4S

You are most welcome. Couple of quick observations:
- too much time between off throttle and brake
- off throttle looks too slow and "leasurely". They should be sharp
- simulated brake trace looks to be ramping up too slowly especially in T1, Inner loop and toe of the boot and T9
- you shouldn't need to brake for T10
- etc.....

cre8fun

yup, off throttle to brakes - lots of time there. I feel that on the track as a place for improvement.

given it's a calculated brake trace from Long G data, I get there's noise, like I'm not braking in the outer loop, that's likely feathering the throttle till the camber comes in.

But the general shape of the brake application/release, I can see what I'm doing in the entrance to the bus stop and not sure what I could change (that being the biggest speed decrease, maybe it shows the most). So there's a small initial step which is transferring weight to the front tires, then there's a high spike which is straight line braking, then there's a step down in "pressure" as I turn in and carry the braking to the curbing. and during that last phase when the brake pressure decreases, the Lat G increases so G_sum is relatively constant. So in the braking into the bus stop, aside from bringing v_max closer to brake application, not sure what I should change about the "shape" of the calculated brake trace?

Frank 993 C4S

Michael, here are three more charts for Watkins Glen:
- Top is speed, then actual brake pressure and then Matt's calculated brake pressure formula from Long-G and then GSUM on the bottom
- You can see that the calculated brake pressure from Long-G is actually a very good approximation to actual
- The chart on the bottom shows the trace for going into the Inner Loop with a high initial application and then a bleed off as you trail the brake into the turn. I am sure a pro would do better but the general principle would apply
- The last chart is a brake trace going into the toe of the boot

GT3DE

You are staying on the brake too long. Should be full throttle again before first curb going into bus stop.
ProCoach and I disagreed about this a few years ago (same year I set track record in E, which has since been wiped away with the repave and Dan Martinson).

cre8fun

GT3DE - thanks for input.

Frank, thanks for data. easier to understand when you know what it's supposed to look like. Plenty of data to dig through, very helpful. That application is damn near vertical. I think I'd lock my fronts if I did that. I'll play with it.

Thundermoose

Not as quick as Frank, but here's mine.

cre8fun

i guess the good news is I've got lots of room for improvement

Thanks for more data

Frank 993 C4S

I think all cars area bit different. I need to let my car "set" after jumping over the first curb (all 4 wheels are in the air) before I give a very quick steering input to the left and then apply full throttle all the way out. The repave has lowered the curbs so you tend to take more of them. The third curb in the Inner Loop eats front left Pirelli tires.

The brake traces in my '69 911 and my 944 look the same. It's tough to lock up the wheels at initial application given their spinning momentum, but you need to bleed off brake pressure to prevent them from locking up, especially if you are trailing brake into the turn.

coryf

Is this a pdk or manual? The throttle trace under braking looks very strange. Either hitting gas and brake at the same time or awkward throttle blips.

Thundermoose

I had the same thought. It's an E46M3 with 5 speed manual. I don't usually try to heel toe 5-4 downshifts so I think I may have got my feet tangled up there. I plan to look at some other laps to see if it was indeed an anomaly.

ProCoach

Super slow (and LONG) throttle blips...

Thundermoose

I created a math channel to filter out pedal position when braking to make it easier to see blipping. I looked at a bunch of other laps at WGI and VIR and I don't think it's throttle blip per se. I have some laps that are very clean with quick blips as you would expect but I also have a number of laps where I see these fat and tallish blips even in places where I know I am not downshifting (and blipping). I think I am just sloppy with getting my foot all the way to brake. Since I have a number of laps with nice sharp blips, I am confident that I CAN do it. Yet another thing to work on.

Bill Lehman

Frank, Could you please post the formula for UnderandOversteer math channel. Thanks.

Frank 993 C4S

UndersteerOversteer = abs(Act_Wheel_Angle)-abs(Ackerman)

where

Act_Wheel_Angle = steering_angle/STRATIO

and

Ackerman = 7.969/ ((GPS_Speed*1.467)^2/(GPS_LatAcc*32.167))*57.2958

and

STRATIO = 22