throtle steer/lift oversteer

I took this out of context from another thread

MC,
If you are who I think you are, you are driving or racing a C6 and I'm racing a T1 C5Z06. I have very little experience in this car but mine does push like a pig regardless, so far, for how I have it set-up. I’m a rear weight bias guy since forever. I have not even tried your technique in the C5 maybe because my comfort level is not good for that technique. Often in tail-heavy cars that can be the kiss of death if the car gets away from you and perhaps having that experience makes it difficult for me to execute your technique. Instead, on a turn like you describe, I’ll go in hot enough to ensure I will feel the push. Then I’ll throttle steer to get the point in/car rotation to get out of the apex on the gas. I can do this because the C5 has more horsepower than grip. I would think your technique would be more for an underpowered car that does not throttle steer but a vette could use either technique. I could never do this in my 348 racecar…no power and it was set-up to oversteered. Do you use both these techniques and when would you choose one over the other?

 

Actually I am an open wheel racer, but I probably am the person you are thinking of

Yeah, you know what helps immensely is if you can do a car control class with skip barber, or otherwise play on a skidpad. Sometimes when I go to track days out here I head out to the skidpad during my breaks. This stuff is not natural for me so I need practice practice practice and "in the heat of battle" is not the best place to figure it all out! I've taken the skip barber car control 3 times already (learning more every time of course) and hope to be able to do it at least once/year. I realize the instructors do this all the time, but I am amazed when they get in the car and show you how to do it ... first time, perfectly. Or, they hop into driver's seat in my street car which they've never been in before, and within half a lap are driving at the car's limit. *If only* I could eventually get to that point!!

Yeah I use both techniques and not sure why/where each comes into play but if you are going to make me think about it, I guess for sweepers I do more of the throttle steer and for sharper/shorter turns I would lift/point. Not because one technique is better for any type of corner -- I wouldn't really know; probably more just because that's what feels right to me. For example, T7 at infineon is a double apex lift corner for me and a great place to practice the technique. For one reason, unlike every other corner at infineon there is an infinite amount of asphalt runoff there so a mistake isn't a problem (just check traffic behind you when going in). For another, the track is basically flat there all the way through the turn so no odd car handling issues to complicate matters.

My car has more grip than HP so I think you're right, that makes things easier. I do tend to get myself into trouble easily with high HP cars.

My guess also is that the less compliance you have in the suspension, the easier it is. My race car has full spherical suspension with essentially zero compliance (only that of the tires), so the car reacts immediately and smoothly (well, as smooth as your inputs).

 

here is nice example of a bit of that today that I did :

http://www.youtube.com/watch?v=sGwCWqC1XwY

 

FBB, I'll take a quick stab at this.

As I’m sure you know, the physics is straightforward. Lifting the throttle shifts weight to the front and unloads the rear, which induces oversteer. Getting back on the gas induces understeer.

For certain corners, such as T5a and T6 at VIR, a quick lift rotates the car and keeps you from dropping your left front in the dirt at the apex of T6.

Based on my experience, though, you can’t compare front v. rear enginned cars. Personally, I love the motor being up front because this is what I grew up with. When I drove a C6 at Bondurant (on run flats, no less!), it was a hoot. You’re right, a Vette has more go than grip, which means you can throttle steer all day long, and the C6 was very linear. On long sweepers, you can dial in just about whatever slip angle you like.

However, I have also spent some seat time in a Spec Racer Ford, which is a totally different animal. The lesson I learned the hard way was, “When in doubt, gas it.” Talk about snap spin. The one thing you don’t want to do is lift while in a corner. The reality is that I don’t have enough seat time to be completely comfortable in a rear-enginned car. This is why I went with the Skippy MX-5 over the Formula car. The Formula cars are better race cars (real race cars don’t have doors), but the Miata fit me like a glove.

Your thoughts?

Dale

 

Seems like you drove a little bit slower after the exit than the entry?

You may have the same problem that I have. Namely, I have a edge phobia and tend to pinch back in instead of tracking ALL the way out. In a 360, if you over turn the wheel on your exit and lift even slightly, away you go! The key is to stay on gas and let the car unwind.

I'm glad the Porsche guy wasn't on his cell phone.

Dale

 

I absolutely do.. I drive my cars at the track probably between 5-8 on a scale of 10 as far as intensity goes.. I have no interest in destroying my automobiles.. maybe I will spent about 20-30% of the track day at 8/10th but the rest of the day I take it easy.. many of the people I race with are at 7-10/10th the whole day.. so I usually let people pass..

It's was also cold that day and I tend to feel a lot more comfortable in 70+ degree weather when racing.. cars stick more encourages more risks..

the goal is to have fun.. not ruin you day.. yesterday a 997 gt3 that was driving at 10/10th all day crashed and did some major damage to the car.. it was at the end of the day.. whenever that happens I just hate looking at the drivers face because it's just awful..

the best racing days are the ones where you have fun and don't destroy your expensive toys

 

MC - You're pretty much there! You were flying in the atom at the last track day in your first session out. Its just seat time that makes you confident in your skills and for many of us, we have 8+ years racing, coaching and high performance driving under our belt. Plus we get to "play" on the skidpad on a regular basis to help us stay fresh. '

When are we going back out to the track in the formula car!

 

I had a great weekend at the thunderhill national last week. Not that I finished so well (which I did! but that's not it) but that I learned an awful lot. So much so that I'm going to try the pro mazda again in April and see if I can transfer any of that.

I forgot to reply to Dr Who's comment in another thread that when he gets beyond 8/10ths he starts to lose focus. I myself have been unable to complete a race without getting more and more nervous, and inconsistent, as the laps go by. Until last weekend! That was the first race where I ended the race just about as calm as I started it (ie, merely excited as opposed to about to have a heart attack!). The whole thing was very cool and calculated. I finished 2nd, right on the gearbox of the winner (0.27s gap).

 

I'd like to get to that point.. where I know what actions will result in what reprocussions.. I just need a lot more seattime... would be nice to be able to learn the limits of my cars so I can really push them at the track.

 

Bingo. That's the way you learn the limits and the appropriate response to the car's reaction when you get to those limits.

Robbie and I spend a LOT of time on the skidpad. That helps enormously. I started autocrossing (Alfas, 308's, a TR and a Daytona {?!?!?}), which helped me stay at a speed that if I lost it (or more correctly, didn't pick up on what the car was telling me was going to happen), I didn't have anything to hit except cones.

The key is to approach the limits slowly and with the correct plan to fix it already committed to the subconscious, which is what they teach at JRRS and SBRS.

The definition of the limit is where the smallest control input change makes a difference. If you can make big changes and it doesn't make much difference, you're either under or over.

MC, when you say you "overdrive" into the corner and then lift to point the nose in, you may be closer to the limit than you think and the car is just responding as it should. Ideally, a "breathe" of the throttle would do the same thing if you were on the edge.

Dale, the key is to do this enough so that you recognize and plan in advance the car's movement and motion. In a good car, I am progressively applying throttle from the entrance of T4 at VIR, short shifting and carrying through progressive throttle application at T5, short shifting again and then whacking the throttle hard, falling into that little pocket or bowled and on-camber depression at the curbing on the apex of T5A.

If the car is not as good, I need to breathe or lift to transfer weight forward to get the front to tuck in.

I was driving a new creation the other day after the owner had it out on South Course as he was watching from the timing tower. He said it looked "spectacular" as I "drifted around T6." I can tell you. In the car it was sublime!

YMMV.

 

remember, you've only been racing for a year so this season should show much better results and consistency. now you can focus on the bigger picture then learn all the little things that are needed to go fast. good luck this weekend!

 

Okay, I'll bite. What's the new toy?

Dale

 

Voila!
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Better ones. Rosso Scuderia!
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^^ You need some cooler looking numbers!!

 

Master, I am but a lowly grasshopper and cannot begin to comprehend your wisdom. So WTF is this?

Dale

 

Bike engined?

 

Nope, Lola T-598, a fully aluminum monocoque to the rear bulkhead, then tubular engine bay/transaxle/rear suspension supports.

2-liter German Ford SOHC, highly restricted. Slicks, 4-pot calipers and vented two-piece rotors all around.

Twenty-five years old. Replacement for the FIA Group 6 2-liter class of two-seater sport racing cars in the mid-Seventies and still being built today in Sports 2000 and the VdeV mold. An extension of the Lola T-290/Chevron B26/Abarth SE cars that ran at LeMans and the 1000KM races, they ran British SuperSports in the early and mid-Eighties, often with alternate automotive based engines.

Unbelievably fun to drive, relatively inexpensive to own and maintain (due to the Formula Ford 2000 specification motor restrictions). A real drivers class!

Track days, contemporary racing or historics, you can do about anything you want with it. Big following in UK, Netherlands, US and picking up Down Under.

 

To get back to the original topic, I'm intrigued by the notion that in order to achieve desirable characteristics changing the direction of a car on a race course, that one feels they have to "overdrive" the car to get it to the point where a control input will effect that change.

Ideally, there should not be an excess of anything (control input amplitude and rate, velocity in or out, pitch or yaw) required to realize the normal and desired handling of a car on a race course. I used to have spirited discussions with Steve (enjoythemusic) while he was enjoying his 308 on track being one of many "talking him into" buying a purpose built race car, which he ultimately did. It was only then that he realized how much he was struggling trying to get the 308 to stop, turn and be balanced, the last quality being the most important.

While I agree that more often than not I need to "throw it in there and let God sort it out" with production based cars (particularly street cars), it was a LONG time before I realized that the sooner you make changes to the car to make it do what you want, WHEN YOU WANT, the better off you are. It's safer, you learn more and it's MUCH easier on tires! <grin> The lesson for me was don't get wedded to a particular way the car drives and instead, make changes and evaluate. I'm not talking tire pressures, I'm talking springs, shocks and sway bars...

 

Well...your post is very thought provoking and I for one do not know the answers to your questions but I can comment on points and maybe you can clarify. First, I think the most significant difference of a purpose built race car vs. a street car for racing is weight, and design compromises. With that said the PBRC was designed for the course before the first tube was welded and so there-in lay the compromises of that design. So with a PBRC is it supposed to do everything we ask of it? I say that because I think that because even with a PBRC course designers do not design all the turns exactly the same on the smae flat piece of ground. The banks, the bumps, the off camber, the hills, the elevation change to name a few items change the needs of the chassis. So the great thing about a PBRC is that you have easy access to guess or test what the ideal suspension set-up should be. However, somewhere there will be at least one turn the car does great and one turn the car does not do great. So on that turn that the car is not great you have to evaluate the importance of the turn to decide if a set-up change is needed. So if you decide no change is warranted then you have to drive the car to make the most of that corner and that could mean you need to throtte steer it or lift oversteer or whatever you have in your bag of tricks. Do I have this logic right so far?

With the high performance streetcar turned racecar we have an advantage that as a bunch of dummies with shallow pockets we hope that the manufacturer has got us half way there to a decent car. Only with lots of money and time can we test to find out how to maximize the chassis and remove as many of the streetcar attributes as possible. A disadvantage is that with a PBRC like say a formula ford everyone from generations ago knows how to make one fast and knows if you as a driver are fast or not. In a new GTR Nissan who no one races nobody knows if all the development is a good or bad thing or if you are fast or not because there is no data. The other advantage with streetcars is that they are crash tested. When we weld in cages we hope to have all the designed safety and hope that the cage we put in adds to the safety system and no compromises it. Yes a cage can be worse if not done right. But a cage done well can improve your safety over an untested or minimally tested PBRC design. So in the end I like modifiying streetcars to be converted to racecars because they make me feel safer and at least some of the development for a road worthy car is already done for me by people with really really deep pockets.

Finally lets go back to the PBRC well set-up and I'll ask you this question. What percentage of the time is the quiet driver (smooth gentle inputs etc..) faster than the busy driver? I know that in equal cars sometimes the gentle guy is faster and sometimes the busy guy is faster. In my own opinion I think that to develop as a driver you want mentors and coaches who exhibit both traits to the extreme so that as a driver you can learn to use all the tools and decide what works best for you at this point in one's development.

 

FBB, I would never dream of trying to put words in Pro Coach's mouth (although I guess this is what I'm doing), but I was told a while back that a real race car doesn't have doors. The point is that a production-based race car will NEVER be as good as the real thing. This is why you don't see any FXX's at Le Mans. The results would be embarrassing.

Based on my own personal experience, the difference between a highly modified Miata and a Spec Racer Ford is night and day. The SRF will bite your butt in a heartbeat, but you can do things in that race car you would never even dream of in the Miata.

Getting back to your C5, I'm trying to remember, but there was one turn at Bondurant, in the C6, where the fast line was to deliberately upset the car so you could rotate it around the corner. In other words, you have to be a better driver to hustle a production car around the track instead of a full on racer. Kinda really makes you appreciate those old Cam Am drivers, huh?

Dale

 

Ahh... I love the Lola 598!
My first real race car, I ran it in SCCA Nationals, the Slick 50 Pro series and the ACRL Pro series.
S2000 is a fantastic class. The cars are very quick. There are some very talented and competitive drivers in the class, but it's also very friendly group. The cars are easy to work on and relatively inexpensive. Huge bang for the racing buck!
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