Ya’all Come Back Now, Yah Hear By Dyke Hensen

Ya’all Come Back Now, Yah Hear

By Dyke Hensen

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NNJR’s High Performance Driving program is one of the finest in the country offering Safe, Se-rious Fun for the faithful. If you haven’t tried it, you should. Track junkies, Auto-crossers and Car Control Clinic veterans, “we want you” coming back year after year and contrary to what your insurance carrier may think, it’s not an oxymoron to have the words “safe” and “racetrack” in the same sentence.
Faithful, you have been doing HPDE for a couple of years now. You understand the “racing line”, threshold braking, and heel-toe down shifts. Best of all, at your last event you were pass-ing cars in your run group. You have already upgraded to performance tires, swapped out your street brake pads for squeaky performance compounds and installed that shiny red fire extin-guisher that tells everybody in the mall parking lot you mean business. But before we all run out and buy that fresh set of R compound rubber, let’s do a quick refresher course on what to do when things don’t go completely to plan.
There is no substitute for “seat time” and the best place to learn the “limit’” of your car is an open parking lot; preferably at the NNJR Car Control Clinic or Autocross. Repeated drifts, slides and spins in an open parking lot will train your three-axis aSSelerometer to know when you can save the car and when you are going for a ride. Spins happen; it’s part of the learning process, but it doesn’t have to be an expensive lesson. Knowing what a car feels like before it gets beyond your ability to correct is analogous to a major league batter waiting on a fastball. It’s easier to hit a fastball if you see it’s coming and it’s easier to avoid a spin if you can “feel” it coming.
When you were starting out your instructor calmly reminded you, “If you feel the car is going to spin; GET ON THE BRAKES, come to a complete stop and stay in your car with the brakes ON”. But it never happened. It has always been “the other guy”. The majority of spins should never happen and we can fix most of these situations before they result in a spin with a little practice and a better understanding of recovery techniques.
But, what do you do when you are “the other guy” on the threshold of a spin? First, relax, most of the time a spin results in nothing more than a bruised ego, a slightly uncomfortable conversa-tion with the chief instructor and four slightly squared off tires that go thump-thump-thump for a run group session. But what if we could have “caught it”?
CPR
CPR is an acronym used at many driving schools and it stands for “Correct, Pause, Recover”. CPR best encapsulates the process you should follow if you are losing or have lost control of your vehicle on the track.
1. Correct
“Correct” means getting the car under control with all four wheels tracking in the same direction. Let’s apply “correction” to the most common type of spin; an over steering car on exit. In an oversteer condition, the back end rotates to the outside of the turn and the front of the car is no longer pointed in the direction the car is traveling but to the inside of the track. Turn “into the skid” to get your front wheels tracking in the true direction the car is traveling. Turning into the skid will reduce the rate of rotation. The earlier you can get this done, the better. It can be a quick “flick” of the steering wheel or a smooth measured input depending on the speed you are traveling. Correcting an oversteer skid is a “right now”, real-time adjustment. A half a second late may too late. Add the correction early and precisely with just the right amount of steering input and you can reduce or eliminate the rate of rotation to regain control of the car and regain car control.
Ya’all come back now, yah hear – Dyke Hensen
2. Pause
“What do you mean PAUSE!!!! My car is sliding sideways, and you want me to pause?” Yes. After your initial correction, the car needs time to settle on the suspension and begin tracking in the direction your front wheels are now pointing. I find that saying “Com’on Darlin” is just about the right amount of time to pause and it never hurts to speak lovingly to your car at this moment in time.
3. Recover
As you regain steering control and are tracking to an area you feel is safe modulate the brakes to slow down If you have “corrected” without leaving the track surface scan all three mirrors, (count them 1-2-3), slow down and plan to visit pit lane to have your car looked over.
If you have left the track surface, meaning you have two, three or four wheels off the pavement remember that grass and dirt offer very little lateral traction to support a turn and wet grass of-fers less. Get the car completely under control, slowed down (a LOT) and tracking straight be-fore you even think about returning to the track. If you have spun the car, come to a complete stop, stay in your car and DO NOT be in a rush to re-enter the track. Catch your breath, wait for the flaggers to give you a signal and then drive slowly around the track off the racing line and make your way into the pit lane.
The best ways to avoid the above scenario: Don’t put yourself into that situation.
Cars go off the track in turns, braking zones, and driving down the straightaway. No area on a track is completely safe, but some sections are safer than others. New tracks, old tracks, bumpy tracks, cement patches, pavement sealer, hills, camber (banking) will all change the grip level of your car on the track. On your first warm up laps, look for tire marks where others have spun and make a mental note not to be “that guy” in that spot. Conditions continuously change through out the day. Cold tracks and wet surfaces will dramatically affect your cars handling and braking. Sand, oil, antifreeze or the remains of a migrating army of earthworms after a rainstorm can be anywhere on the track surface. Note everything and then take the time to talk to your instructor and other drivers to learn what areas of the track to pay special attention to and why. Understand the track conditions and be aware they can change in an instant.
“Catch and control”
Very rarely do DE drivers come into a turn so fast that the turn-in itself causes the car to spin; it’s slow recognition of a compromised line and the over reaction to it that does us all in.
You initial input to steering should be gradual and smooth. Don’t be misled when you see a video of a professional rapidly spinning the wheel from side to side. This is rarely their initial input, but a reaction to the car “stepping out” and the driver “catching” the car as it does. In most cases the driver is expecting it. Even though they may be sawing the wheel from side to side, the result is a “smooth” and stable platform.
Ya’all come back now, yah hear – Dyke Hensen
As you progress and drive faster, your braking and turn-in reference points will come up faster and you will rush your turn-in resulting in a line that leads to an early apex. It will happen. As you know from your whiteboard sessions an early apex causes your car to track out early and requires you to increase steering an-gle in order to stay on the track at the exit. The first time it happens, the realization comes about100 feet before the track out cone.
Our primal brain, the medulla oblongata screams “we’re going off” and our basic survival instinct tells us “hit the brakes and turn the wheel to stay on the track!” Bad idea Medulla. Lifting off the throttle or hitting the brakes while changing the steering angle will spin the best handling car with the most advanced electronic traction controls. The irony is that you could have made the turn in most cases with a slight correction done earlier. In the above diagram, 100 feet before the exit cone maybe too late.
Let’s dissect an early apex situation and understand exactly why the wrong reaction to it will cause the classic “lift-throttle oversteer on exit” spin.
In Car and Driver tests, a 2012 Porsche GT3 RS weighing 3,200 pounds meas-ured 74% of the weight of the car on the rear wheels under acceleration, but only 42% on the rear tires under braking.
Think about it, that’s an absolute change of 32%, or close to 1,000 pounds!
Increased weight equals increased tire friction and grip, removing weight reduces grip. You can shift hundreds of pounds off the rear tires just by simply lifting off the throttle in the middle of a turn!
“Lifting” off of the throttle and increasing the steering input 2/3 of the way through a turn will cause the car to “rotate” and may put you into a spin. As the car pitches forward in reaction to lifting off the throttle, it transferred weight off of its rear tires on to the front tires. Less grip in the rear (perhaps compounded by additional steering input) induces lift throttle oversteer. It will happen in a new 911, Cayman, Boxster or 944. Older
Ya’all come back now, yah hear – Dyke Hensen
trailing arm suspension designs will actually “toe in” as the rear end raises up and wheels drop down through their suspension travel arc providing the classic double whammy 911 “snap” oversteer. It happens in early 911’s, 356’s and early BMWs and it can happen in a blink.
Recognizing early when you have taken an early apex line will allow you to make corrections in the entry and center of the turn. A little more trail brake or a little less throttle will “tuck” the nose of the car into the turn and tighten your circumference.
In all cases, at track out, use the entire track and do not “hold” an over steering car to the inside of a turn. Fight the urge to lift or hit the brakes on the exit of a corner and correct with just enough steering input to reduce or eliminate the rotation. If the conditions are dry, you can even afford to track wider and use the outside of the turn as “run out”. This is a much better option than “yanking” the car back onto the track if you put two wheels off the pavement inviting a high-speed spin across the track. The downhill at Lime Rock Park is a good example where you do not want to abruptly lift out of the throttle and add steering angle in an effort to hold the car on the pavement at the exit. Doing so will loop you to the inside of the track. Look for all the tire marks at the exit of this turn and see where they go. Spoiler alert, they track from the outside of the turn across the track to the inside tire barrier before pit in.
In all cases, when a driver abruptly loads and unloads the suspension by lifting on and off throt-tle or going on and off the brakes throughout a turn it never allows the suspension to settle and never allows your car to reach its maximum cornering limits.
Braking spins
Next up on the spin-o-meter are braking zones. If we were in a race and not an HPDE, braking zones would be the number one hot spot for thrills chills and spins. But this IS a HPDE and we are not challenging for position into Turn One on the first lap; right? So what could possibly go wrong? Well, lots of things. If you apply the brakes abruptly and turn the wheel, the rear of the car will rotate. Teach yourself to release brake pressure as you initiate the turn in.
Even if you brake in a straight line in early cars without ABS you may have to deal with both front and rear tire lockup. Rear tire lockup can actually make your rear end “hop” off the pave-ment. Even with a new car with ABS, a poorly synchronized downshift can make your rear end hop like a bunny. In both of these scenarios, you DO NOT want to add steering to try and “make the turn” as the rear of the car can rotate very quickly with comprised rear tire grip.
You will “feel” front-end tire lockup and wheel hop, but you don’t always “feel” just rear wheel lock up. You WILL feel the car isn’t braking as effectively as it did the lap before. In this case, it’s better to “trust your butt”. If it doesn’t feel right when you are threshold braking, something isn’t right. If your rear is locked up and you turn in, your Porsche will react just like the hand-brake turn you did with your parent’s sedan in a parking lot and spin like a top. Play it safe and use the run out at the end of the braking zone if something doesn’t feel right. If you don’t have a run out, use as much track as you can to slow the car down before you try to turn in even if this means driving wide of your turn in point. Even if you “made it” check for smoke in your mir-ror as the telltale sign of tire lockup.
ICE-ICE Baby
On newer cars, the dreaded “ICE-Mode” pedal is a new wrinkle added in place of rear brake lockup. ICE-Mode is caused by a confused Dynamic Rear Proportioning valve (DRP) and can be activated by bumpy tracks in combination with aggressively “jamming on” the brakes. When the ABS software senses rear lockup, it restricts additional hydraulic pressure to the rear brakes
Ya’all come back now, yah hear – Dyke Hensen
based on a pre-programmed algorithm allowing the rear tires to continue to rotate. As the valve closes in the master cylinder to the rear brakes lines the brake pedal feels “hard”. In theory, you still have full brake pressure and modulation on the front calipers and pushing harder may apply more front brake pressure, but we have experienced instructors and racers that would dispute that this “theory” is of any real value. If you are threshold braking in a braking zone, you are likely close to 100% of your front brakes capacity and pushing harder is not going to help you slow down. You have about 1-2 seconds to figure it out.
If you cannot slow the car down by simply pushing harder on the brakes, come off the brake pe-dal and reapply the brake firmly. The assumption is that releasing the brake pressure will allow your wheels to roll again and reset the DRP value to a normal “dry” brake bias. If it doesn’t work, try it again while looking up for run-out extension. Fortunately on most of the tracks we run there are run-out areas at the end of the longest straights; use them!
OK, you get it, incidents happen in turns and during braking, but did I mention the straightaway? Yep, been there, done that. I had my 911 hydroplane and spin as I lifted to brake on the front straight at Watkins Glen in wet conditions. We then pirouetted down the straight through the braking zone, past the turn in and up the “escape” road. Round and round we went for probably 800 feet in total. It’s always better to be lucky than good, and that time I was very lucky.
You know what they say, Lift Happens
Unless you are driving a true down force car, (you are not) aerodynamic lift happens when you add speed. You can feel lift when you are at high speed on a straight by the “lightness” you feel in the steering. The same or more lift is happening at the rear of your car. A modern Porsche adds a lot of speed on a straight and your automatic pop up spoiler or aftermarket wing reduces lift, but it doesn’t eliminate it. As your car loses down force, it becomes much more susceptible to cross winds and yes, hydroplaning, in wet conditions. Anytime the coefficient of friction of the track is compromised, bad things can happen even when you are driving in a straight line. At 120 MPH, you are covering the length of a football field in 1.6 seconds and it will take 4 times the distance to stop at 120 mph as it would when you are doing sixty. So, don’t relax too much on the straight.
Remember, your car has built up serious potential energy according to Sir Isaac Newton’s F=ma, as in Force = Mass multiplied by Acceleration. While on the straight, try to anticipate EVERYTHING that could go wrong. Be sure you have a view of the car in front of the car in front of you. If a car blows up halfway down the straight and the two cars in front of you hit the brakes, have a “plan” for where you would place your car. If you are hounding the driver in front of you trying to “encourage” that car to give you a passing signal, you may not see what is going on in front of them. With speed, you have reduced your downforce and added serious potential energy (Force). Be very attentive to track conditions such as debris, a disabled car or in my case, running water flowing down in the groves of the “dry” line in turn one. Bottom line, you can never be looking “too far” down the track at speed and you should always have “a plan”.
Fast Car – Slow hands
On fast straights and fast sweeping turns add this new “Law” to your track day Wikipedia, FT=SH. “Fast Turns = Slow Hands”. You can’t toss the car around like you can at a 35 mph autocross at speed. Slow your steering inputs down and give the car time to react and settle so you don’t overcorrect and make things worse! When a car gets loose at a high speed, you can still use CPR, just slow down your inputs.
CORRECT “SLOWWWWW HANDS”
Ya’all come back now, yah hear – Dyke Hensen
PAUSE “Com’on Darlin, please….”
RECOVER “Phew, that was interesting”
Moment to Moment
If you find yourself losing control on a straight or on a very fast turn, it is rarely the first variable that gets you; it’s under or over correction to it that puts you over the limit. Think of a “fishtailing” car, the first moment of inertia leads to an equal and opposite “moment” of inertia. What typically happens is the driver has not brought the wheel back to a straight ahead position after the initial step out of the rear of the car and then holds the corrected steering an-gle to long as the car rotates back the other way compounding the effect of the second movement. As the driver gets behind on the correction input the car ends up fishtail-ing. If you come to the car control clinic, I’ll show you a technique where you let the wheels “slip” through your hands as the car recovers from your first moment of inertia and starts to swing to the second. Left alone, your front wheels will track very quickly to the exact vector your car is currently traveling and then track precisely to your forward direction magically through the car’s rotation. It’s Caster, a Friendly Ghost.
One Good turn deserves another
OK didn’t mean to scare you, because it’s all worth it because here is what it feels like when it all works. When you enter a turn, you load the front suspension by braking or simply turning the front wheels. With street cars, this loading takes time as the car transfers weight to the front tires and then to the outside wheels. As the weight transfer equalizes against the spring rates and friction force buids, the front end of the car takes a positive ‘set’. As the car changes direc-tion, the load transfers to the outside wheels. The front-end will turn in smoothly with the rear tires following from the pivot point originating from the center of gravity of the car. The sense of rotation you feel from the rear of the car is called Yaw and it should be smooth and predictable.
In a well-executed turn, the rear of the car will drift to a point of equilibrium equal to the “Moment of Inertia” balanced against the frictional resistance of the tires as you turn in. As you track to-ward the center of the turn the frictional force provided by the turn will continue to reduce the speed of the car. At the center of the turn (true apex) or just before, you can offset this deceler-ation by gently adding throttle balancing the weight distribution between the front and rear tires. As you pass through the apex you can feed in more throttle, moving more weight to rear tires then as you slowly unwind the wheel to track out you can continue to feed in power. When it’s right, your car turns in smoothly, is balanced in the center of the turn and on exit, the rear end squats down, “hooks up”, the engine sings, the steering feel lightens and you rocket out of the turn with a huge grin pressed against the sides of your helmet. That’s the dance and the warm embrace your car will reward you with if you can consistently and smoothly “balance” the weight distribution through the entry, center and exit of a turn. If we could only do this perfectly every time, we could all quit our day jobs, but even professionals get it very wrong sometimes. But when it’s right; it’s a beautiful thing.
One last thought: The last run of the day
Skiers have a saying that goes something like this, “Don’t take the last run of the day”. Why, because everyone seems to break their leg on the last run of the day. I know, it’s hard to take another run with a broken leg but humor me here. You are having a great weekend and pro-gressed in every session. After the first couple of laps in your afternoon session, you blow two turns in a row. It happens especially when you have fast Freddy in your mirrors. Next lap you blow past a braking zone and miss the turn in. Your car is running perfectly, but you’re not. You
Ya’all come back now, yah hear – Dyke Hensen
are tired.
With all that adrenaline pumping through your brain you may not feel the fatigue but your concentration is waning and your reaction times are compromised. Point Fast Freddy by, check your mirrors and gages, work on your lines, and drive at 8/10’s. You made it this far without having Jay Mazzola, body man of the stars, look over your car and shake his head. More importantly, it’s an NNJR event and there will be plenty of cold bev-erages waiting for you when the track closes. Think of coming in a few laps early and then you CAN race Fast Freddy to the cooler.
See you in the spring.