gkmccready

Okay, this could be interesting, or not, but here goes. Yesterday I was out at Thunderhill in my '06 Z51, modifications were a harness, -1.1deg front camber, -0.9deg rear, and PFC01 front pads (PFC Z rears).

My driving style is typically trail-braking transitioning to light throttle mid-corner and winding it open on corner exit. I was running group B since it was my second event in the car, and second at Thunderhill, so I wanted to get used to things without entirely open passing... plus the run groups were very slim so there was plenty of track per car.

In any case, my late-braking, trail-braking technique was feeling good, but then one of the group A drivers broke his turbo Miata and dropped down into group B with a C5 Z06 ... he was all over me. His corner exit speeds were way way higher than mine, so much so that I thought he had motor modifications -- he said no, just that he wasn't trail braking, and he had more "trust in his tires" (we were both on the stock Supercars). I was running with all the nannies off, he said he was in Comp Mode.

About all I could garner from talking with him was that he doesn't trail-brake at all, and he just throws the car into the corner, and (I assume) gets back on the power much sooner than I do/can. He did say that my line was good, so I'm having a bit of trouble wrapping my brain around this.

The last two sessions of the day I was trying to modify my driving style, which is pretty hard given I started out in FWD and learned to trail-brake everything to help rotate the car... that said it felt like I was getting much better mid- and exit speeds from some of the corners trying to power through them earlier rather than leaving the braking so late. Others just felt like I had started pushing way too much.

Let's see if I can run down some of my entry/exit speeds for corners at Thunderhill... T1 is an 80mph entry, T2 is a 60-65mph entry, T5 (Cyclone) is 35mph, T6 is 60mph, 75-88mph at T7, T8 is 80-85mph, I hit 105mph before braking for T10, full-throttle in 3rd through T12 & T13 -- maybe a small lift at T12, 110mph at the bridge before T14, and exit speed is 75-80mph off T15. (http://www.thunderhill.com/html/trackmap.html)

So... I seem to be able to hustle the car okay, but it was an eye opener when that C5 Z06 came out and was just all over me... so somewhere I'm leaving a lot on the table and the Z driver pointed to my trail-braking technique. Comments from the masses? How do you drive these cars? I want that corner exit speed but from my seat of the pants it felt like I had so much lateral load on the car I couldn't get much/any more acceleration out of it -- apparently I'm wrong about that somewhere, or my line doesn't lend itself to it.

Help! :-)

glen

PS- Gary! The harness bar, belt mounts, and Jet Pilot harness worked great! The stock seat is still a bit of a liability, but it was much much nicer than the stock 3-pt!

MattW_VA

Well, first of all given = drivers (which never really happens anyway) I think you'll find the C5 Zs to be a bit quicker than our C6s. Even though they are only rated at 5 extra horsepower don't they tend to dyno about 20HP greater? Also they are a tad lighter.

You should read through some of Lou's posts here-I think his approach to finding speed is really intelligent, and obviously it works for him!

Having said that I'm trying to find some speed myself at two of my fav tracks-I'm several seconds off the pace of where I feel I should be-but that's the fun!

Bob 33

What you really need is some seat time and instruction from some of the hotshoes who populate this Forum at a forthcoming HPDE event. It will be a revelation! Unless you are already an expert driver, and few of us are, car-specific verbal advice of the sort that you request will not be very valuble.

Bob 33

gkmccready

Dunno about how the dyno numbers play out. I read Lou's posts and they're definitely good information. My transition from Honda Civic->1st Gen RX7(s)->2nd Gen RX-7 Turbo->Corvette has put me in a situation where I've now got torque, and gobs of rubber (in comparison) and I don't think I'm utilizing it very well yet.

I wanted to blame things on lack of grip because I thought I was getting what I could out of the stock tires, but after watching that C5Z launch out of T15 and pull several car lengths on me ... I think there's more in what I already have...

AU N EGL

I am bring a bunch of east coast hot shots to Thunderhill next Nov for a NCM event. But that is too long to wait.

In short rember:

Late apex
Slow IN, Fast out.

gkmccready

I suspect I'm forcing myself to try to make the straights too long, over compensating from moving from momentum cars to the Corvette.

Instead of just late apexing, I think I'm late braking+trail braking+late apex rather than just braking a bit earlier, late apexing, and getting back on the gas harder, earlier. Does that make sense? In most corners I seem to wait to brake, brake hard and start turn-in as I'm backing off the brake, *****-foot the gas mid-corner, and then get on it at exit... I do late apex but I'm trying to sort out if perhaps I should brake a bit earlier and then I could carry more power through mid-corner? The latter approach really seemed to help me in T8 in the later sessions.

I'm hoping somebody familiar with Thunderhill can read into my entry/exit speeds and see if that's the case. :-)

When can we sign up for the Thunderhill event? I'm out for atleast four months starting soon, anyway, due to shoulder/elbow surgery. :-(

Sidney004

What is an NCM event and when is it?

2000BSME

It has been my experience (limited as it is) that z51 suspension components are no match for z06 ones. My brake usage went WAY down when I fit my '99 vert with z06 springs sways and shocks.

AU N EGL

What is it?? a High Performance Drivers Event. No not a waxer contest.
It will be based of our other events here on the east coast
http://www.corvettemuseum.com/regist.../infocmp.shtml

TENATIVELY First weekend in NOV, 2007 ( Next Year) at T-Hill. We have a meeting this week with some NCAL ppl who will help us get instructors.

Every student ( except advanced) will have their personal instructor.

Plus we bring 10 GM & Corvette Engineers to our events.

StArrow68

"I am bring a bunch of east coast hot shots to Thunderhill next Nov for a NCM event. But that is too long to wait."

Another with interest in the visit to TH. Any chance to join in the
planning?

Randy

Glen, It's hard to judge from entry/exit speeds since most instructors have told me not
to look at the speedo, although since I leave the HUD up it's hard to miss. I'm in a stock
engine C5 on street size Z06 rubber/wheels. At Spring Mt. the instructors teach no trail
braking in the entry 3 day class and then in the advanced 2 day class they get those that
are comfortable with it back into it and say it picks up lap times, fwiw. I don't do it since
I run mostly with the systems on and it messes up entries compared to making a smooth
entry with the car balanced as you roll onto the throttle. I'll be at Sears Point, NASA event
next weekend both days trying to pick up speed without trail braking.

AU N EGL

Randy send me an email.

Tom

Aaron Pfadt

It's hard to give or get the full picture on a forum, but my general first impression of your technique is this. Trail braking can be a useful tool, it is sometimes needed to get a car turned in the right direction. Your description is that it is your method for most if not all the turns. The short answer is brake less, you'll go faster. The Z06 driver's technique which you described as throw it into a corner and power out, is probably a good description of the way a fast driver will get around any course.

Where you are using brakes to rotate the car, he is using momentum. His car is dialed in enough to turn in (he may be trail braking still, just at a higher speed) and when the car starts to rotate, he catches it with the throttle. It can be an unsettling technique, but when you are doing that, the car is approaching the limits of adhesion and are relying on weight transfer to keep the cornering properly. On GY F1 Supercars, that technique will even look a bit sloppy because of the way those tires act.

It is something you will work up to. I strongly encourage you to get a coach for your next session at T-hill or any track you know reasonably well. The coach should drive your car with you as passenger. It will be eye opening. That is how you will get fast. The coach should be a racer also, not a DE star. In general, only racers are really fast (the last two seconds of any car), and certainly not all of them are either. Ask around, there are a bunch of fast guys that coach in CA. PM me if you need a suggestion.

Good luck, and take it as a lesson learned that most never understand. Most people roll around the track thinking they are fast, very few actually are.

-Aaron

96LT1

Trail braking is a useful tool to have in your driver's kit but shouldn't be a crutch for every corner in our cars. You have more than enough power under your right foot to rotate the car without trail braking. If you are going into a corner really 'hot' then trail brake it or get the car drifting to help scrub speed.

As mentioned there is 'racer' fast and then there is 'DE' fast and the two shouldn't be mixed. If for no other reason then the differences in car prep, (tires and brakes minimally).

Everyone has their own style but I'd say that if you are getting consistent pushing than you aren't using the throttle enough to rotate the car.

Bob 33

As Aaron suggests, get a coach--a fast one. While all instructors teach "smooth is fast," there is "slow smooth" and "fast smooth." I've learned the best lessons from the "fast smooth guys," mostly racers, present and past, and some DE guys. It's usually obvious when you have screwed up and why, but I have benefited most from those likely to say "great save, now pick off this next guy," than "we had better slow down and focus on the basics." One weekend, I had the instructor who provided the latter quote, later being promoted into his group and lapping him while he drove ultra-smooth, ultra-slow laps in his C5 Z06. Try to find a driver/instructor who can best teach what you want to learn.

Bob 33

gkmccready

The technique you describe isn't really unsettling; that sounds like my trail-braking technique... you bring out something that the C5Z driver said that didn't sink in at the time, though, and that was if I just let the car scrub the speed off rather than trying to trail-brake it to the limit I'd probably be faster. That sounds more like what you're describing as momentum.

The more I think about my PFC 01/Z compound combination the more I wonder if the street pads on the rear cause too much front brake bias and unweight the rear of the car which is really unsettling the rear during my trail-braking. The Z driver said he was watching the rear wander and me catch it at corner entry while he was basically driving through.

As for a coach/instructor, as I said, that was my plan but none of the 'vette boys showed up yesterday outside of the C5Z so there was nobody to steal a ride with. :-) And I already knew I wasn't fast in the Corvette which is another reason I was running around in Group B working on technique and line before going to Group A. :-)

This is all new since the 1st gen RX-7 was underpowered, the 2nd gen RX-7 was a turbo which meant using the throttle to set a line through the corner was difficult, and, well, the old Civic was driving the wrong wheels. Just going to take a little further adjusting, I guess...

Unless I'm reading the various comments incorrectly, I'm hearing something like slow a bit earlier, minimal trail-braking, power through from mid-corner out. Versus my brake late, heavy trail-braking, easy throttle to set the car through mid-corner, and power out at exit.

Somewhere you have to trade lateral grip in on that acceleration, though, but evidence would suggest that the lower mid-corner speed turns out to be a win on the exit.

mountainbiker2

On corner exit are you using full track width? Right to the edge. Where you thought that 1 more mph you would have run right off the track.

Steve

StArrow68

Just a thought on coaching, NCRC has the ARC group run as well and there are several that coach in the intermediate run groups. Most groups seem to have instructors for entry level and then nothing beyond that, NCRC coaches have helped me several times at different tracks and it is something you can request when you sign up.
Randy

gkmccready

Nah. Not in the intermediate group at a DE event. Perhaps the other guy was pushing harder, but it was a pretty extreme difference. I was tracking out okay, but it wasn't a 10/10ths situation riding the slide all the way.

gkmccready

That's a good thought. I really like the TEAM events, though. There's something to be said for knowing and trusting atleast the organizers if not the rest of the folks. Not that the other groups aren't well run, etc, but I've known Bonni for several years now.

I really think this is just a car-specific technique/line issue for the most part... not that I'm a great driver but I think I'm just missing that little something to hustle this car closer to its potential. The fact that in over 4.5 hours of track time I can probably count on one hand the number of times I've had the car even briefly step out on me is probably pretty telling... I've got a lot more to push/offer and right now I'm just trying to figure out how much more the car has before I have to push that limit.

Bill Dearborn

After reading your description of what you are doing it really sounds like you are not trail braking in the true sense. If you are trail braking you should make a gentle turn in during the initial braking and then gradually decrease brake pressure as you increase the turn in. The idea is to combine an early corner entry (heaven forbid early apex) at higher speed and use the braking while turning to rotate the car onto the normal late apex line on corner exit. This gives you a faster corner entry that is closer to the cars limit and allows you to keep the fast corner exit of a late apex turn. It also is gentler on the car since you are making a gentle turn in Vs the late apex sharper turn in. Another benefit it is also the shorter distance through the corner.

What it sounds like you are doing is trying to follow the normal late apex corner entry and combine that with some trail braking as you make your turn in. It sounds like the other driver is braking late and hard and turning in on the late apex line and using the throttle from the turn in point to corner exit to rotate and balance the car through the turn.

If you can get your turn in started earlier and gentler (just a slight touch of the wheel at first) you will have a faster corner entry and that will carry through to a faster corner exit once you have mastered the technique. Your speed through the turn will probably end up being faster than the Zs driver if he continues to follow the late apex line.

Bill