smf32s

Just curious, how high are your pressures under very hard braking in a 997.2 Cup? It came up this past weekend at a race and another driver and one of the esteemed coaches on here made it very clear I need to up my game. Squats I guess are in order. Anyway, what pressure are you getting?

I'm only around 800 lbs. I do have StopTech brakes though.

Thanks for any input and thanks to that coach and that driver that kicked my butt this past weekend.

Stu

fleadh

Pressures will depend on pad, caliper and master cylinder configuration. Don't worry about them.

Are you having any lockups? If not, hit it harder.

Might help if you show a couple threshold braking zone traces from your car.

ps: if you run old pads it'll feel like it requires a lot more pedal pressure.

-mike

smf32s

No lock ups. I have Teves abs. I don't have the car here to pull the data. The traces looked like my friends. Virtually straight up to a high peak then trailing off with typical fluctuations as it goes down. Pads and rotors in very good shape. Using PFC 11's too.

Car stops fine from 160 or so at around 300 or so near the watch billboard on Road Atlanta back straight.

Sorry for lack of more info.

Stu

amso3

Hi Stu

Porsche used more than one type of bp sensor in the 997 cars. I work with a bunch of 997's and we have three different senders. All senders use the same configuration in Motec and I am convinced that the pressures aren't really comparable car to car. The Teves also makes it non-comparable to non ABS cars. I'd compare longitudinal G values, rather than pressure. Tell me what track you want to look at, I have lots of Cup data on many of the tracks you drive (NJMP and Sebring), I can send numbers

smf32s

I was at Road Atlanta this past weekend with VIR, Watkins, Nj Thunderbolt, and Summit Point in the near future.

Thanks

stujelly

At daytona with cup calipers I was hitting 1100 to 1200 in turn 1.

You can program your shift light indicators to do the opposite of the the RPM. So as your pressures increase it light up from the outside towards the center. That was helpful to me

jcastle

Pay a pro to do a data lap in your car. I too thought I was hitting the brakes hard, but the motec data showed differently. After seeing the pro's max brake pressure, I recalibrated the brake pressure scale on the smartycam. Also created some lockup lights in the motec to give me visual warning of when I'm getting close to maximum brake pressure. The smartycam can't show brake pressure in the cup, so will have to look at maximum g's.

amso3

Here are a couple 997.1 laps to compare to your data

smf32s

I've seen the shift lights do that on a friends Cup car. That's a great idea. I'll ask my crew if they can program my lights to do that. It would be kind of fun too.

Thanks for the idea and thanks for the brake pressure traces. Definitely a few good ways to start.

Stu

neuroguru

800-1000 PSI on OEM pads / rotors in my 7.2, however I have new Bosch ABS and am a novice cup driver. My shift lifts are programmed for brake pressure, too. I love it.

CRex

Brake harder. Don't stop until you lock.

On a combined basis I peak at approx 120bars. That's about 1,700psi across both axles, split roughy 55/45.

FYI I'm running RST1 on Pirelli DH, 275 fronts and 315 rears.

CRex

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fleadh

IMO, If you simply drive to lights at a specific pre-programmed brake pressure you're never going to optimize your usage of the brakes.

However, I am a believer in lockup indicator lights as you're learning to get a feel for lockups before they result in cockpits full of tire smoke. :-)

Just my 2c. Find whatever works for you.

-mike

smf32s

I agree. Although I have Teves ABS so lock up is not my issue. I'll see if the lights can be programmed to a certain pressure which I would imagine they should be able to.

Stu

tedean

I work at determining the max long G for a track, then work to achieve that. I also have lockup indicators on the MoTec shift light module. One blue light right or left for front lockups, two blue lights for rear, left or right. Then I adjust bias accordingly (as long as I'm testing the bias in a straight line). I have found pressures all depend on track temp, track conditions, tire temp and overall grip factors.