Larry Herman

Ok, I guess that I wasn't reading your post correctly. Anyway, as far as a carousel goes (any turn of relatively constant radius greater than 180 degrees) I have always favoured the double apex method. Dive in as fast as possible, maintain an arc that takes me out to the edge of the track, and then back in to accelerate past the second apex and onto the straight. If I just hug the inside waiting for the point to get on the gas, I feel that my exit speed is slower.

Remember, that every turn is different, and there may be reasons for taking "non-standard" lines. The Carousel at Mid-Ohio is an example. You DO want to hug the inside, because the right handed carousel bends into a left handed turn onto the front straight. You would want to stay on the inside so that you could properly drive the left hander to get speed onto the straight.

ColorChange

Yep. Sounds good!

Brian P

The cooler is installed and I'll give it a test this weekend at Watkins Glen.

smokey

Bill, just following up on your discussion of Mark Donohue and Jackie Stewart: Road and Track magazine ran a test comparing Jackie Stewart driving a data-logging car against one of the R & T writers in the 1970's, and compared the results, trying to figure out why Jackie was so much quicker. Jackie was quicker because he was more consistently either fully on or off the brakes and throttle. In that test, the data proved to Jackie (much to his surprise) that he did indeed trail-brake, even though he had always claimed that he didn't. After seeing the data, Jackie was convinced. I believe I still have the article, and I'll try to dig it up. At that time, Grand Prix cars had no data logging. Except for the stopwatch.

sjanes

OK, I'm starting to get confused here. CC is agreeing with Larry, but if I'm reading Larry's posts properly, what he is saying is the opposite to what CC is saying. This is how I'm reading each approach:

Larry's approach: Get most (if not all) of the braking done in a straight line, trail off the brakes on turn-in to settle the car, and then full-throttle from there to the apex and beyond. Larry seems to agree that some entry speed is given away with this approach, but that he gets it all back (and more) with the hard acceleration in an F class car (i.e. not high HP). There is no constant speed/neutral throttle phase to this style. This seems like a "slow in-fast out" syle to me, but maybe I'm missing something.

CC's approach: Carry as much speed as you can into the corner, using trail braking as far into the corner as the situation permits, neutral throttle from there to the apex, and accelerate from there. I read this as "fast-in/fast-out".

So, am I reading these posts correctly, or should I get another coffee?

As an aside, I has an instructor (who is a club racer) at Mosport a few years back that suggested Larry's brake/turn/full-throttle method to me and I didn't get it. It seemed to me that to get full-throttle after turn-in would require over-braking for the corner, whereas I was trying to carry as much speed to the apex as possible (using slight deceleration after turn-in). I tried the instructors approach and it didn't feel as fast (I wasn't timing/using DAS, so I don't know), but it seems to be working for Larry.

mitch236

I think it depends on how much power the car has. In my instance, most turns I can get back on full throttle once I have turned in. In a high power car, getting on full throttle before the apex may lead to an off track excursion.

Neutral throttle at mid-turn should be fastest for the reason of contact patch management. But remember that in normal powered cars like mine, being full throttle at 2500-3000 RPM is fairly neutral throttle! If you are really accelerating between the turn in and the apex, you probably overslowed the car before entry. (given a constant radius turn)

M758

I am with Chris and ColorChange on this trail braking concept.
I posted this in another thread, but feel like it is critical to this discussion.

Here is what I consider to be a difference between the slowin fast out and fast in fast out concepts and straight line braking vs trail braking.



The real trick to being fast is to balance the car in the "partial braking" zone.
That to me is part of the fast in idea. Note that I show a release of the brakes before the apex. Given my current driving ability I found that I need just a bit of time to let the car transition from braking to acceleration. If I try to brake too deep then I can't seem to get the car set-up right for accel and actually lose speed.

Not sure what "ideal" is given that each corner and car set-up is a little different and you really need to find what works best for the car and driver combo.

I have said it before and I will say it again. If you race me in a 944-spec and limit your braking to only in a straight be prepared to see me lapping you during a race. The tracks we run on braking after turn in is 100% required to get more speed. The guys that can feel comfortable balancing the car on turn in are the ones that are 2-3 seconds faster per lap. In driving a 944-spec if the car feels nice and stable in corner it is because you are going too slow. A DE envioroment is completely different from racing in this aspect. For DE stable good. For racing stable is slow.

I have done two races with Chris in 944-spec car. He beat me both times, but I learned tons chasing him. I remember on practice session at local track. I tucked in behind him at the start and stayed with him for nearly the entire session. In the process I did alot of braking after turn in and I also ran 1-2 seconds faster per lap for that entire session than had been my previous best.

macnewma

At my first DE, I was taught to straight-line brake. I thought this was interesting because I had read a few books that advocated trail-braking to maximize lap times. The books only discussed this in theory, so I thought maybe it wasn't applicable for some reason. I had too many things to worry about at that time so I just did as my instructor told me (or at least tried).

Afterwards, I revisited the books and did some research. I found that trail-braking is advocated, but what is gained is really that last 1%. The other issue is that by attempting to achieve that last 1%, you risk losing time. It appeared to come down to a risk/reward proposition. The books didn't discuss this because they were generally interested in presenting the theory of the absolute fastest lap time.

Here is a quote from Brian Beckman's Physics of Racing Series:
He goes on to estimate that it accounted for 0.5 seconds on a 1:40 lap at Sebring. Obviously, this is not huge, but it could be significant assuming both drivers are of the same skill in equally capable cars. For us amateurs, in either DEs or Club Racing, very few of us are skilled enough that we are tapping the other 99% of the car's potential. Should we try to squeeze out that last 1% afforded by trail braking? Even within that last 1%, you can achieve different degrees of maximization.

From watching CC's track video, it is apparent that he is nowhere near maximizing the other, simpler skills that amount to 99% of achieving speed. (BTW, I am in the same boat). Should he concentrate so heavily on maximizing that last 1%? In theory, yes. In practice, no.

I think of things in terms which I know better. I will use a golf analogy. I equate trail braking to the technique of controlling ball flight. The difference between a 15 handicap and a scratch golfer is not the ability to control ball flight. There are a multitude of other skills needed first. Once those skills are mastered, the difference between shooting 2 under par and 4 under par could be the skill of controlling ball flight.

I know for a fact that both Bondurant and Skip Barber schools teach trail braking. To the best of my knowledge, PCA DEs typically do not advocate trail braking. My explanation for this is based on what they are trying to achieve. DEs try to teach people track safety first, speed second. The race schools need to provide the driver with the best set of skills to go as fast as possible. They have a concern for safety, but that isn't what people pay for.

I, personally, am happy learning the DE style with straight line for now. Once I feel that my skills have maximized my lap times to where I could use that last 1%, I will seek that skill.

Max

mitch236

What I posted about was mid-corner speed and not trail-braking. I am with the trail-braking camp, but I don't think I trail as far into the turn as the drawing depicts. I use trail-braking as a way to rotate and compress the car. I am usually trying to maximize contact patch area and don't see how deep trail-braking helps that. If one were trying to maximize cornering force, then one would have to keep the balance of the car as even as possible.

Now, correct me if I am wrong as this is just my thoughts.
When you turn in, you are compressing the front suspension because of the increased friction from the front tires, this is like braking with the front only.
If I get back on the throttle just after turn in I am now loading the rear suspension. This should balance the car somewhat.
Using CC's friction circle, this balance should give me the most available lateral g-force and therefore allow for the greatest speed during the static turning phase (mid-corner).

I find that most drivers enter the turn too slow (especially the heavy trail-brakers) and then try to accelerate back up to speed which creates an unbalanced situation. The available lateral g-force is reduced because of the greater demand on the rear tires from the acceleration, and that leads to a slower mid-corner phase.

The other situation I see is the DE approach. If you come off the brakes before turn in you unweight the front and this unsettles the balance and results in less available lateral g-force. The reason this is taught is obvious, safety. It is not fast.

The best corner is fast in, fast through, fast out.

M758

Well sounds like they are not doing it right. If you look at the picture you should able to enter the corner fast if you are trail braking. Reason is that if you brake in a straight line you must slow the car BEFORE the corner. If you trail brake you can slow the in the corner. Plus we all know places were the fast way through a corner is to touch the brakes to get the front end to bite and then we can make the corner. It is not really to slow the speed, but get the car to stick a little better. Same thing with trail braking. It also allows for a little more rotation a better stick so you can infact turn in a little better too.

Another aspect is not shown is that by trail braking you can also initiate the turn in a little sooner. All too often in straight line braking you need to slow the car down to the "turn in speed" before you turn. Well alot of times that means as you push faster you tend to reach that turn in point little later thus making the situation worse since you just make tigher radius corner than needed.

By turn in while still on he brakes you can effetivly begin the turn a bit sooner and then tend to make larger radius turn thus carrying more speed. A good trail braker is going much faster at corner entry than a straight line braker.

If in the example above you straight line braked then got on the throttle a little just after turn in and were on the gas the entire way you would be slower.

Reason is balance. When on the throttle and attepting to turn the car will tend to understeer since the grip is at the rear not the front. When you have understeer the car needs to be either going slower or making a larger radius.

If you are braking an turning the car will want to oversteer thus the natural tendancy helps your turning process thus allow a tigher radius or more speed for the same radius turn. Cleary too much brake to steering input and you can make that natural oversteer tendancy that helps you turn and it will help too much causing spin.

It is the guy that can use the physics of weight trasnfer to help him turn the car just the right amount that will be faster at corner entry and faster at mid corner. Of course being faster at mid corner is key since then you start from a higher speed to accel out of the corner. The trick is to get this just right. I did an autocross in my stock 83 944 on street tires. By removing the spare tire in the rear and running low fuel I had the car rotating extermely well. This meant I did not need to slow down very much even for the many 180 corner. I was even able to control this rotation very effectivly at corner entry and mid corner. Problem was that at corner exit even with low hp I began to over power the rear tires and could not get the power down. So I added back in the spare tire and took out some oversteer. Next runs I still had the car rotating very nicely. But the extra weight just gave me enough grip to get the power down and go faster overall. I also did a run with a passenger. In these runs the balace again changed to more understeer. Since I had a little more difficulty rotating the car I had to slow more for the corner. Thus while I could get the power down overall times were slower.


Yes I trail braked all the 180 corners at the even. In spite of the balance of the car my trail braking allowed me to set the rotation to max level I could handle on turn in to whip the car around. Of course that max level was determined by balance of the car. By constantly being on the brakes and learning to modulate them to keep the balance It was easy to change how much brake I used to suit the balance of the car and maximize the avalible grip and know how much to exceed the rear grip to maximize corner speed. If know for sure that If I did not trail brake the car I would have to guess how fast it would go around the corner. Go too slow and leave some thing on the table. Go to fast and then you need to slow even more to make the corner.

ColorChange

Smokey:
This I can believe. Boy would I love to see that article.

Sjanes:
No, I don’t think Larry is saying to get all the braking done in a straight line at all. Most of it on most turns, sure, but no where near all on most turns.

The best approach for most turns (not all) I think is to:

#1. Trail brake to near the apex (almost never after, sometimes to, usually before, and sometimes well before the apex).
#2. Hit the neutral phase of the turn with neutral throttle near the apex (often near, often at, rarely after) pulling max lat g’s.
#3. Squeeze the throttle as soon and as much as possible (often before the apex, often just after the apex, rarely much after the apex).

Mitch:
Your point about full throttle at low revs actually equaling neutral throttle (constant speed) is a good one. I agree that if you are accelerating before the apex, you way over braked on most turns.

M758:
I agree completely and the picture was nice. Great post.

Mac:
Good post. I generally agree with our post but dispute the time magnitude.

In the Racecar Engineering article “The Line King” March 2004, the timing difference for a hairpin turn using trail braking was over 0.5 seconds in one turn alone. Trail braking isn’t a little faster, it’s a lot faster especially when combined to the correct line. In the Trail Braking article in the August issue, they show that combining line and trail braking for a high hp car, the difference in one hairpin between the classic line and tb line was 2.2 seconds! For one turn!

I agree that I am nowhere near refined in all the other areas, but I see no reason not to continue to trail brake as I’m not flying off the track (frequently at least). If you don’t want to, OK, whatever you prefer. Your way is probably safer, mine might learn a little quicker as I won’t have anything to unlearn later.

Mitch
When you turn in, you are compressing the front suspension because of the increased friction from the front tires, this is like braking with the front only.

Only if your brake bias is way off. Sure the fronts do most of the braking, but nowhere near all. If so, use more aggressive pad at the rear to get more bite and better brake balance (simple fix).

If I get back on the throttle just after turn in I am now loading the rear suspension. This should balance the car somewhat.

If you do this shortly after turn in (normally), you over-braking. You should be maintaining speed as you approach the apex, braking as late and deep as possible.

Using CC's friction circle, this balance should give me the most available lateral g-force and therefore allow for the greatest speed during the static turning phase (mid-corner).

When you gradually release the braking, you transition to neutral throttle smoothly pulling max lat g’s around the apex, and then squeeze the throttle in the vicinity of the apex.

I find that most drivers enter the turn too slow (especially the heavy trail-brakers) and then try to accelerate back up to speed which creates an unbalanced situation.

Could be, especially in a low hp car. In a high hp car, you V it more, in a low hp car, you arc it more. It’s all a question of magnitudes. If you apply throttle and brakes smoothly, there should be no car upset.

The available lateral g-force is reduced because of the greater demand on the rear tires from the acceleration, and that leads to a slower mid-corner phase.

Yes, that is why you normally begin true acceleration (not neutral throttle) after the apex.

The other situation I see is the DE approach. If you come off the brakes before turn in you unweight the front and this unsettles the balance and results in less available lateral g-force. The reason this is taught is obvious, safety. It is not fast.

Actually, I think the car will have a little better overall lat g capability, but you can’t use it in the early phase of the turn because you are just building lat g’s alone (when you could be still bleeding long g’s using tb at the same time).

The best corner is fast in, fast through, fast out.

Truer for low hp cars, less true for high hp cars.

ColorChange

Great post again M758!

ColorChange

Just for the record, in the brand new F1 racing magazing (September), they have telemetry data for Webber and every turn the show he trail brakes a lot.

TT Gasman

I haven't read this whole thread so I apologize if this has been brought up, and I am far from being an expert on this subject. I have always been a traditional slow in fast out straight line braker, until I attended the Porsche Driving Experience in Birmingham, the race driver/ instructors really stress trail braking on most turns, Dave Murry even told me "if you're not trail braking you're not road racing". So I have tried this at DEs since coming back from the PDE and I seem to be a lot faster and more consistent around the track FWIW. It is something I will continue to work on and use in the future.

RedlineMan

Busted?

I love it when people play rough! Only in the sense that I am not willing to swallow whole, esoteric theoretical arguments that I agree with, but that don't apply to most of our driving or our situations. That has been and continues to be my stance.

I have never dissagreed with Color's theory (as much as my lame brain could follow it), merely his insistance, especially based on paltry exeprience. The three most important rules of driving; Application, application, & application. His videos have well illustrated that he is in general missing the essential and formative 99% whilst grasping for the last elusive 1. Theory is the easy party, my dears. It is in the application where the flies summarily find the ointment!

I seriously question whether he has the skill to pull it off before he developes the other fundmentals to do it effectively, his above average mental capacity for advanced driving thought, and his applicable advantage in ski experience notwithstanding. That goes for you too, Chris, and all of us. Do you/we have the skill to do it yet? More than the vast majority in your case, but less than others, eh? At what price? Your own car, or as a hired gun, someone elses?

It took a novice to really shed the Light of Truth on this theoretical paradigm, now that opinions have converged on this issue. Max completely nailed the real world situation we deal with. If you are the guy who has to find a ride home, and pay a flatbed charge for 3-4-500 miles because you stuffed your car, then you would be looking VERY critically at your decision to try and maximize g-sum by trying to trail brake to the edge of control without going past it.

I can boil it down to this. I drive with 2600lbs and 147hp, 150,000 miles "strong." I drive pretty quickly. If the driver is the limiting factor in the equation, then I'm no different. I know that. For guys in similar cars, or even much faster ones than mine, who are not cornering as quickly, what is their point in wanting/owning a faster car? Until I get 100% out of mine, there IS no point. I'll stay in the lower impact regions, thank you.

If you need that last 1%, then where you will find it is right between your ears. It is an EXTREMELY fine line between trail braking to save your *** and trail braking to maximize your entry and through speed. I have been doing the latter for many years, and studiously avoiding the former! That's why I don't race (for one thing).

TB is a fact of advanced driving. I just do not TEACH it because most people are not equipped to handle it at the point in their "careers" that I see them. That would include Color, but I'd teach it you, Chris.

When I get an advancing driver, then I will teach it because they will need it!