SundayDriver

I thought I would pull out a separate topic about early/late apex from another thread as it an interesting topic and is getting lost in the other thread...

So what is the correct apex and line? In my experience, there are two considerations - step one is to find what line give you the quickest time through that one corner. Step two is to decide if you want to give up something in elapsed time in trade for something else.

In my experience - my own personal growth and coaching/instructing, I can say that almost everyone goes through the same process, though some people never complete it. You start with taking pretty much everything early - that is the nature of begging to drive. Just watch people making left turns at a large intersection - almost everyone has to tighten the steering to miss the inside curb at the end of the turn and not cross out of their lane. So instructors are always pushing to take a later apex.

But like all good things, we all tend to take it too far and by the time we are intermediate/advance students, we are taking a late apex and tend to think that is right.

Finding the ideal line is not all that hard. At no more than 8/10ths, you should be able to take a smooth radius corner with no adjustments. Turn in, apex and track out. If you have to correct (forget bumps or weird radius corners) you are not on the correct geometric line. At speed, you will have to start the turn earlier and likely aim for an earlier apex in order to actually hit those marks. My bet is that if you do this, you are going to find that you are taking a lot of late apexes which will show up by having track remaining at track-out.

Then you start the process of trade-offs. Each corner is unique in that regard but there are some easy guidelines. A corner at the entry to a long straight favors exit speed over all else. A later apex provides this. How late depends on the car, but the difference in apex points between low hp and high hp is generally no more than a few feet.

A corner following a long straight is where you want to hold the high speed as long as possible. Early apex (and probably fairly heavy trail braking) are the ticket here. Corners in between corners are the least important and you make lots of compromises here for the first and last corner. Alan johnson has a book (pretty old) where he outlines these at 3 types of corners. It is a great read.

One last concept in deciding on tradeoffs has to do with where you sacrifice in a long series of corners. If you lift at lower speeds, you can regain that speed much quicker than if you lift at high speeds. In a series of turns you want to do pretty much everything you can to take the last corner flat. Think about three turns and you can take the first two flat but have to lift for the third, leading onto a straight. the faster way through is to lift for the first, then be able to take the next two flat. The Esses at places like Buttonwillow and Sears are just this case.

38D

So very true. Some of the DE cones are often set 50'+ after the "real" apex (heck, I might apex the carousel at the Glen 100' before the cone!). One good way to find the real apex is to follow the concrete. In general, 2 wheels inside, and 2 wheels on the concrete is about right.

M758

Apex at the earliest possible point where you can apply full power and still barely keep the car on the road.

However in my mind the most important part of the corner is not the apex, but the braking & turn in point. Those need to be set-up just right so that you natuarally hit the apex and track out points you need. Get the braking and turn in points right and you will flow to the apex and track out fast and smooth. Screw the turn in and you will fight the car all the way around the corner and this will be slow.

In my experinece most DE driver start their turn in WAY TOO LATE. I believe this is symptom of teaching "late apex" and "straight line braking".

BTW... for me you apex'ed to early if you had to lift or ran out of road on the way out of a corner. Apex'ed too late if you had plenty of room on the way out of a corner.

As Sunday said there may be times you want to apex really late or apex early and give-up the corner exit depending on the track and corner sequence.

analogmike

Good info from Joe P, I heard this line 20 years ago and thought it was a joke but it's actually the best one line speed tip:

The key to speed is to late apex as early as possible

Bob Rouleau

M758 - the late apex and straight line braking before turn in promote the safest cornering. That's why it is PCA doctrine. Will the guy you teach ever come back to DE? If so, as skills increase you can back off the extra safety margin and teach trail braking, earlier apex, and early turn initiation (to account for greater slip angles as Sunday observed above).

Sunday - your introduction sounds correct to me. The only input missing is adaptation based on the car itself (understeering versus neutral or oversteering) and the ability of a car to accelerate. In a really powerful car, a later apex will provide more exit speed. In an lower HP car, momentum is all and an earlier apex will be preferred since there might be little difference between entry and exit speed (944 NA comes to mind).

best,

Professor Helmüt Tester

A sub-topic - what about 'angle of attack' ? Sure...it's an aerodyamics term, but it means something here, too. There is a gentleman around these parts who does private coaching of professional racers, and he spends a lot of time with them discussing the position of the car during the whole corner, not just dealing with the car as a single entity without any of its axes.

What is the attitude of the car (physically...not mentally) at the apex ? IMO, it's very important for certain corners. Defines whether you've thrown it in early & sideways to maximize exit speed, or whether you've squared it off as a setup for a following corner.

A 'for-instance' ? How about Oak Tree at Nelson Ledges ? There are so many different ways to drive that corner...and at least 3 different 'fast' ways...and it's all about apex, angle of attack and how comfortable you are having the car hung out sideways on entry, knowing (hopefully) that it will 'hook-up' shortly and you'll get to the Carousel before all those other jerks.

Z-man

I like that! If you think about it, it does make perfect sense!

Thanks Mike!
-Z.

M758

I fully understand this point and it is what I teach to novice students. However the best apex for fast laps and safe DE line is not the same. I think we can both agree on that.

JCP911S

Yes. The apex is just an aiming point.... once you have set up for the turn, theres really not much you can (or should) do to adjust your line.

I tell people its like pitching a baseball.... once the ball leaves your hand, there's not much you can do about it.... this apex is like a catcher's mitt...

TD in DC

Really? I thought the difference between newbies and great drivers is that great drivers recognize when they have made an error a lot earlier than the newbies and have more tricks in their bag to try to mitigate the effect of the error they have already made. I have never had the impression that you are a slave to fate once you have set up your turn.

JCP911S

Well.... its a matter of degree... but my point is that you basically commit to the turn at turn-in... screw that up, and you screwed up the turn... sure you can "mitigate" it but mitigating is the same as losing speed... generally, you adjust by not getting on the gas as soon, and that will hurt your speed.

TD in DC

I agree that it is better to not have made a mistake in the first place, but I have made enough mistakes in my short time doing this that I know of several things I can do to fix it, some involving my feet, some involving my hands, and some involving invocations of faith and promises made with every intention of keeping them but which all too frequently are forgotten by the time I have reached the same spot during the next lap.

M758

95% of the time when you start your turn it is wrong by a little bit. Then you need to correct it.
This happens for a number of reasons. 1) of those is that we are imperfect drivers. Other reasons included changes in grip that occur when are at the very limit. Some corners are such that you have to work a little to keep the car on the line you choose.

You are correct in that if you screw up turn in you are often struggling to get the car around the corner. Getting it right makes it so much easier and smoother and thus faster.

Bob Rouleau

JCP - I agree with you but only up to a point. If you make a gross error at trun initiation then I'm with you. On the other hand the idea that once you've made the initial turn of the wheel you're stuck with the outcome is untrue in my book. As TD says, it is rare that we turn-in perfectly every time. Fine corrections are not only possible but practiced all the time. Sine they are fine (as opposed to gross) corrections the variation in speed is also very small. Said corrections are almost always needed at speed because the track conditions change with almost every lap, not to mention tires and dimishing car weight due to fuel burn.

I take real issue with the doctrine that says "turn your wheel once and never change it". That's a complete crock as far as I'm concerned. It is correct for some corners only. For example, a 911 likes the "turn, turn more" technique in slow corners. The first is to load the suspension and tires for more grip and the second is to nail the apex.

Best,

SundayDriver

I agree that there are adjustments. HOWEVER, I too often see people on horrible lines claiming that is fastest for AWD for high HP or because their car is yellow. HP adjustments to the line tend to be quite small. I can not personally think of an adjustment of more than 3-5 feet in apex point on any track I have driven and those are the extreme cases.

I don't quite understand about changing the line for a car that understeers or oversteers. For me, when a car is misbehaving, I am still trying to be on the same line but fighting to manage the weight transfer.