I took my CS to a PCA DE and then a Driver's Edge DE in the last month. Thrilling stuff, and I'll be going back for lots more thank you very much.

Can you track junkies explain some of the following terms? I've spent lots of time on track on a motorcycle so don't be shy. Some of the terms overlap I'm sure but it's hard to get in depth explanations when your on track and fighting the red mist.

1. rotating the car
2. throttle steering
3. slip angle or attitude versus turn angle (edit)
4. trail braking to load the front at turn in

Also, the non sport seats really don't hold me in place well even with a C-lock device, had a hard time catching downshifts midturn for a very decreasing right hand corner...any tips or would a better seat be a real improvement.

Thanks.

I too am pretty green at this, but I think I may be able to help with 2 and 4..others feel free to correct me if I have it wrong.

2. throttle steering refers to giving your car some gas when hitting or going around turn, in order to "kick" your rear-end out and if done right, line you up for the exit. I have not really used this on the cayman, but did it a lot when I was driving a Mustang. You could really let the rear out on that.

4. trail braking is when you use your brakes during the turn, versus the "normal" do all your braking in a straight line wisdom. from what I understand, if you trail brake at the right point in a turn (and often a turn does not require this technique) you will push the weight of the car to the front, due to the force of the braking. This in turn, will give your front tires a little more traction and help for the turn.

I think actually 2 and 4 can be used together.

Ok, how bad did I mess all that up??!?!?

Throttle steering is the removal of throttle input to cause the rear end to increase the slip angle, thereby pointing the car into a tighter radius turn. Throttle is then increased as you get to the intended heading.

Dragging the brake induces skidding, which is a similar method, as the traction is also reduced.

Basically, rear engine cars (or near rear engine cars ) have a very light front end. So, when you are flying into a corner, and the front is under steering, aka plowing, then, letting off of the throttle or dragging the brake will upset the traction and balance of the car, causing the rear end to rotate toward the front of the car (think spin), increasing the slip or skid angle. That makes the car turn the corner. But, you need the power to overcome the effect at the right time to keep the car tracking where you want to go.

A great example of this is in the video "Victory by Design", which every Porschefile should see at least once, if not own. Toward the end of the video, there is a guy having some real fun in a 911, demonstrating the technique.

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Cayman S - a portable amusement park

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LL

Thanks for the explanation, very useful when you explain what the technique is used for and when. Please keep it coming.

Victory by Design: Porsche (1:11 running time, 210 MB)

Victory by Design - Porsche

1. Rotating the car - changing the heading of the car, usually done by trailing throttle oversteer but can be done by trail braking, without turning the steering wheel. Trailing throttle oversteer (TTO) is achieved by getting off neutral or steady throttle early to mid corner. Weight transfers forward, the front end gets more grip and rear gets light and car pivots/points toward the apex without any steering input. Works great if done correctly, results in a spin if overdone. On a bike you rotate the bike into the corner when you "back it in" into a corner with the back end hung out. The direction the bike is "pointing" has changed but you are actually sliding the back end into the corner. In a car the same maneuver would be fairly aggressive trail braking where the back end starts to actually come around and you have to catch it at the right moment, by applying throttle to transfer weight to the back tires to give them grip, or you spin.

2. Throttle steering - see above. Adding more throttle (up to a point) will make the car push or go wide. Getting off the throttle will make it turn in better (TTO above). Overdo the throttle (assuming enough power to overcome rear tire grip) and you go into power oversteer. The throttle is being used to manage front to rear weight transfer to keep the car balanced, get it to turn in, or track out under power.

3. Slip angle - all tires have a certain amount of slip at which they actually have the most cornering grip (IIRC 7-15 deg for most tires) any more and you are sliding too much. Maybe fun and "feels fast", but not the fastest way around the track. Also, unnecessarily wears your tires.

4. Trail braking - staying on the brakes slightly at corner turn in to keep the weight transfered to the front to maximize front end grip to get the car to turn in better. Most cars are set up from the factory to understeer (not just mid or rear engine cars), trail braking helps overcome that tendency. Braking in a straight line, getting off the brakes, and then turning in allows the front to rebound up on the suspension and decrease front end grip resulting in understeer (front end "pushing"). My track car (BMW M3) is set up "loose" and does not like a lot of trail braking. I have to get on the throttle almost immediately after turn in to stabilize the car and then use the throttle to adjust the heading. In my car, as with most rear engine Porsches, lifting mid corner is not a good idea, unless it is done to intentionally rotate the car (TTO again).

What are you doing shifting in the MIDDLE of a corner????!!!! If you are truly at the limit of available grip you are almost guaranteed a spin. From your motorcycle experience, you know that the bike is most stable mid corner with at least slight throttle. If you are dragging a knee (ie. leaned over really far) I doubt you would shift at that moment. Doing so would unload one end or the other and the bike would slide out. Cars are no different. Get into the right gear for corner exit before you enter the corner(ie. in the braking zone (toe-heel downshift)).

Hope that helps,

Tom

P.S. I would highly recomend the book "Going Faster! Mastering the Art of Race Driving" by Carl Lopez. It goes over all of this in great detail.

Thanks Tom, super informative post. I see that you instruct. I just ordered "Going Faster...." on your recommendation, great reviews on Amazon. I suspect it'll be the best and last mod I'll get for $20.

About that corner, it's a sweeping downhill right that ends in a very tight uphill right that empties into a chicane leading onto the front straight. A downshift is typical for most cars and per our instructors, I just suck at it. It's an interesting series of corners no doubt. I'm hoping Glenn posts his comments about it since it's his home track, Motorsports Ranch (MSR) at Cresson, clockwise 1.7mile configuration.

On a bike, shifting at full cornering speed is indeed a delicate undertaking, but sometimes it's quick, so the corner gets straightened out/squared off enough to allow the bike to get stood up a touch to allow for it, the corner at MSR is a similar situation. Slipper clutches are quite nice to have.

Now that traction control and computer controlled clutches are in place we don't get "backing it in" shows from engine braking like we used to.

I had Carl Lopez for an instructor with Skip Barber a few years ago at Watkins Glen. Great guy, and I have my own autographed copy of "Going Faster". I went looking for him this last summer at Lime Rock during a PCA DE event and was told he has retired and has gone fishing but still lives in the Lime Rock vicinity.

OK. That clarifies the "mid corner shift" question. I think you get the idea, though, re not shifting in a corner in most situations. (I do it in some corners as well, but I am usually pretty smooth with toe/heel downshifts.) In some sweepers that are taken at the limits of adhesion (Carousel at Road America comes to mind) if you try to shift in the latter part of the corner you will loose it. Most short shift that corner to be in the right gear for the exit.

Read through the PCA regs re. harnesses. You will need seats with openings for the shoulder and groin straps to run in PCA. They will make a HUGE difference in being able to feel what the car is doing through the steering wheel instead of hanging on to it for dear life so you are not sliding around as much. Cuts down on fatigue as well.

I think you will really enjoy the book. It is the best "mod" I have made to the nut behind the wheel.

Tom