Matt Romanowski

It also looks like your Long G are mixed up - braking should be negative. I would guess that you could brake harder as well. .86G isn't really that high. I routinely see deaccell at over -1G.

Veloce Raptor

Yes his axes are reversed, I noticed that, but no big deal.

I actually like that he is braking more lightly, that makes it easier for him to brake less and carry more speed into the corners!

teamking

Respectfully, I don't believe that there is much maximum braking that can be accomplished in the car.

My friend and I switched cars the same day these data were recorded (he has a 2006 Cayman S on the same tires - Bridgestone RE-11), my lap times were a couple of seconds faster in his car than mine, and the braking performance was night and day - I was able to brake MUCH later. On the other hand, he had to adjust his braking points to be much earlier in my car.

My belief is that I'm running so much negative camber that it is dramatically affecting braking performance.

I don't mind being corrected if I'm wrong, and I appreciate the insights about my lack of longitudinal smoothness (in fact, I think the issue is manifest more under braking than throttle, now that I'm looking at it closely!)

Matt Romanowski

No doubt about carrying speed into corners. I just figure it's worth getting things set up right.

Just a guess, but to get a significant change in braking you would have to be running more than -3 degrees. I've attached a file from a 924S at NHMS on a wet track. They got .93 with a wet track, crappy tires, and aggressive alignment.

I have files from a 944 S2 at Summit on a cold day with a very aggressive alignment on old Toyos at 1.07. Just a couple for reference.

teamking

I'm running -3.2.

My experience is that crappy R-comps have more grip than new street tires.

onefastviking

Not too hard to figure out what max braking g force is for any given car on any given day,tire,condition, etc., so you can have a idea of baseline. - Just find one of the straights when no one is behind you and ...... well you can probably figure it from here. Determining what the car's potential max is can help you know what your potential as a driver should, or could, be, although that is not to say that you should be attaining that max in every brake zone.

More g's can be available in some instances when tracks, or brake zone, is uphill, aero is assisting, etc, etc.

pontifex4

I just wanted to jump back a bit to this because I find that I'm doing the same thing as teamking -- only in my case, I'm feathering the throttle until well after the apex in long corners to keep from losing the rear. This is most noticeable to me at my home track (Mosport turn 3, in particular), though I have no doubt that I do it elsewhere, too. If I try the corner a gear higher (4th instead of 3rd), I can't throttle steer anymore. Aside from always looking for a later apex, what can I do?

KaiB

Is this a concern about tossing the rear out or an actual "I'm loosing control due to throttle induced oversteer"?

pontifex4

The turbo boosts very suddenly in my car, due in part to some low-grade tuning. In corners like this one:



...I'm leaving the concrete patch just as the boost is really coming on, but there's still some turning to do, as you can see in the video from where the curbing is off to the right. Sorry for the lack of in-car video. Anyway, it's kind of the perfect storm for me of poorly managing the weight transfer and unfortunate boost timing.

Edit: here's Patrick Long, with commentary. I don't pretend to be able to drive like him, but you can see a pretty good turn 3 line at 2:00, and that's roughly where I cross the concrete, too.

Veloce Raptor

So what's actually happening with the car when the boost comes on in that spot? And help me understand what you mean b y "throttle steer"?

pontifex4

Sorry, I'm sure I could have worded this better, and I don't want to mire the thread in my beginner problems!

I'm finding that I make the transition to oversteer quite suddenly at the point I mentioned, as though I suddenly went from 50% to 100% throttle and jerked the wheel. It's loose in a couple of other corners, too, but those are much slower, shorter ones.

The combination of my line, corner speed and boost make me feel as though I can't roll the power on smoothly enough or unwind the wheel fast enough. Other cars walk away from me on this corner in DEs, though they're otherwise similar to my pace.

(By throttle steering, I was referring to the very minor adjustments I make to throttle pressure before the apex and immediately after to keep the car on line -- as opposed to the feathering I feel I need to do after the apex to keep the car from spinning from the boost cutting in as I unwind).

This is a car with pretty stock running gear and street tires, by the way.

Edit: The Pat Long video posted above has an (obviously) excellent turn 3 line at 2:00.

KaiB

My two cents here...not uncommon.

The 930 was (is) also famous as a "point and shoot" car.

Far be it from me to offer advice on how to handle it on track...the 930s I drove back then scared the hell out of me.

Matt Romanowski

Hey Guys - Dave wrote up a great article for TrailBrake.net on how he, as a coach, uses data to help improve his clients. It's a great article with a good base on what people should be looking at and some of the things a coach can help people with. Check it out at http://www.trailbrake.net/2/post/201...uses-data.html

Veloce Raptor

Hey, thanks, Matt!!!!

paver

I'm a driving rookie. I have been to three Porsche driving schools at Barber. So, my total track experience is 5 light days worth. I'm going to do a DE soon so I need to increase my understanding.

As far as I know, there are 4 critical points in a basic corner:
1. the point where braking is initiated
2. the point where turn-in begins
3. the apex
4. the track-out point

My question is should brake pressure be constant from the braking initiation point to the turn-in point? I think I remember being taught to begin releasing brake pressure as the turn-in begins and to be totally off the brakes just before apex . So, my main question-is there a momentary zone where brake pressure should be constant?

Thanks guys.