I'm with Scorke on the traibraking issue. The purpose is to get the rear tires to slide a little so you can rotate and then start getting on the gas. In a way, it is part of the transition between threshold braking and accelerating, but I don't see how it could possible put more weight or grip on the rear, since braking makes the nose dive, hence the extra weight on the front. So trail braking gives your steering tires more grip while rotation your rear end around to get pointed in the new direction quickly. I wish Will was on these boards, he does it so well I'm sure he could explain it to a T.

Yeah, road courses/canyons and autocross are two totally different animals aren't they? But seriously, I am still a far cry from driving without error myself. I'm sure Will Kalman could hop into my Lancer and get within 1/2 second of his times in the Escort without even getting used to my car.

 

I'm not saying trail braking puts weight on the rear wheels. Rolling on the throttle does that (weight transfer). Your major braking is what is transfering weight to the front tires. Trail braking (dragging your brakes) allows that weight to stay there untill you get back on the throttle.

Lets look at this as if we were traveling in a straight line. Think about how if you hit the brakes hard. What happens? The nose dives down (increasing tire contact patch on the front tires.) Suddenly take your foot off the brake just as rapidly as you applied it. What will the car do? Nose will violently spring back up.

Now, same senario but instead you gently back off the brakes and let them drag a little. The weight transfer is no where near so sudden.

What we need to agree on is yes, trail braking will get you around a corner much faster than not using it.

Will trail braking induce the desired oversteer? I dont see how.

If you want oversteer while going around the corner I would think more power is needed or the case of an Evo with the larger rear sway bar, its going to happen.

Trail braking is all about helping to maximize tire contact patch (better known as traction) and moving the car around on the suspension.

After all in any given corner there is a limit to the amount of traction available to the tires. In a right hand turn your outside front tire has the most weight on it and the inside rear tire will have the least. Using trail braking to gently move the traction from the tires that have the most load to the ones that dont are what its all about.

I think this shows how effectively using trail braking will make going around any given corner faster. By maximising your traction that is available.

This is a great discussion by the way....havent enjoyed these forums this much in a while

 

I think you are confused on the definition of trail braking then. To me, at least, trail braking is used while entering and while going through the corner to change the attitued of the car. Upon corner turn in I use it to get more weight and grip over the front to get the front of the car on the desired path(around the turn.) You are thinking of trailbraking as more of just continued braking than how I look at it. Trail braking, at least when I use it does not keep the front down, but actually brings the front dow. I think to say trailbraking keeps the weight over the front is a bit much, but to say that trailbraking merely transfers weight, instead of keeping it somewhere is much much more accurate. With the evo, over steer is very hard to achieve mid to corner exit without as I said radical suspension modifications, or a lot of power, or some very slippery conditions, however upon corner entrance I PROMISE YOU that trailbraking will make your car want to turn more(rotate).Trail braking isnt about maximizing contact patches, to be honest going from a non trail braking to trail braking state while mid corner probably hardly has an effect on contact patch, but probably has a much more profound effect on corner weights.

Also in your last example, in ANY turn your outside front tire has the most weight on it and the inside rear always has the least, not just right ones .

Trail braking will not make going around any given corner faster, it will provide you faster laptimes mostly from lengthening your straight away(If you do choose to trailbrake by stretching your braking zone into the entrance to the corner), or from allowing you to take a tighter line during the entrance to/middle of the corner which allows you to accellerate sooner.

fingers hurt.........................................haha

Scorke

p.s. same stuff, i love talking about vehicle dynamics.

 

I think we all mean the same thing but the way we think about it is what is causing the problem here. Let me take a quote straight from Bob Bondurant On High Performance Driving

"After the major braking for a corner has been completed, trail braking is, essentially, just riding the brake into the first third of the corner, gradually releasing the pressure and smoothly switching from Brake to throttle.

By trail braking you maintain chassis set. The frint shocks and springs are compressed and you maintain a forward-directed-weight-transfer creating more downforce on the front wheels. This increases the tire contact patcces, which maximizes traction and provides better control."

Thats straight from the horse mouth. A very highly respected road racer and teacher.

 

scorke....it sounds like what you are doing is using the brakes to change the attitude of the car. Which I can see will, depending upon your position in a turn, have an impact on the suspension. IE: loading it and unlaoding it at a given point.

But lets not confuse that with trail braking. The definition that I gave from Bob Bondurant is the correct one.

by the way, my avatar shows a properly loaded front end of an Evo

 

Well, I read the definition and you show a solid understanding of that definition. Perhaps the technique I see tha FWD drivers do would either be a different style of trailbraking or something different altogether, but it still keeps with the Bondurant definition of increasing the front tire traction. He doesn't really mention what has to happen to the rear tires, and we can assume that they are getting less traction already because the car will naturally be in a nose dive position from the threshold braking. Maybe trailbraking is simply holding that nose heavy load for a split second more to help get the front pointed in the right direction.

I agree that this is a very nice discussion. And I love the "properly loaded front suspension" in your avatar. Chicks in bikinis add something like 50 hp too.

 

Well then...the book continues on....

"Ideally one wants the maximum tire contact patch possible in contact with the road. Trail-braking helps to control the tire contact patches of all four tires while entering a turn just as smooth acceleration helps steer while coming out of a corner" -Bob Bondurant

edited for spelling...

 

You pretty much nailed it if you're driving that technique. The key is break early and not late, go as wide as possible and turn in early almost pointing the car as if you're going to hit the cone. As your start your turn in, get on the gas sooner than later. Naturally you will want to induce some understeer with the power. The reason you're pointing to the cone is to allow the car to understeer past it at the same time been spooled up to exit the corner. If you do it right, you'll know right away. If you're too far off the apex cone, you're either adding too much power or you did not turn in enough to have the apex cone lined between your front bumper. The understeer that you will induce will not be a moderate understeer but instead it will be minimal understeer.

 

Oh by the way, unless you're traili-braking with your left foot and staying onthe gas with your right foot, I don't recommend trailbraking with the evo.

The problem with trail-braking is that you're spending too much time on your corner exits. With the evo, you will be so far off boost that you will lose a couple of tenths in the corner and those couple of tenths adds up.

 

My left foot is on the dead pedal.....Normaly my trail-braking is used in conjunction with heel-toe. On these short auto-x courses, I havent found the time to react fast enough between turns to use it correctly. On much larger roads/courses it isnt even a problem. I have had people on my *** in a straight and with proper heel-toe and trailbraking, at the exit of the turn they are already 2-3 car lengths behind and by the time they hit the exit I am on the next straight 10 lengths ahead.

Now in an auto-x depending on the size of 180......I would turn slighty (feint) to the outside to load up the front suspension and try to make it around a single cone. I think slower entry speeds are needed to ensure getting on the gas earlier. Obviously in that situation your exit speed is important. I realize thats a generalization about any turn on any course. Higher exit speed = quicker to the next turn.

 

I think the quote from EVOlutionary is right.

Originally Posted by EVOlutionary

 

Check this out:

http://videos.streetfire.net/Player....term=crash&p=1

 

thats something alright. He wasnt maximizing his tire contact patches. Drifting holds no real place in motor sports, I dont care what Takumi says. Its only an exhibition.

Off topic though...

 

If you go back to the 1960s definition of drifting, it's really just a term to define oversteer. In that sense of the definition, all racers want a little bit of that. Unfortunately, we have become addicted to the extremer, and "drifting" went along for the ride to where it's now a show-off move while legit racers only use the term oversteer. No matter, a little oversteer is good, drifting until you have to look out your side windows to see where you're going... is not. *disclaimer: regarding paved courses

 

I agree with that. Slight oversteer is fast. A true four wheel drift (not the current craze) was considered fast as well as you were/are driving just past the limits of total adhesion for your tires. Bob Bondurant discusses this in his book as well. After all, he did race in that era.....it was a neccesary part of racing.

Urbanknight...have you ever heard of that book before I mentioned it. I highly recommend it. It is so full of information. A lot of it you already know and may not realize and reading Bob Bondurants book just opens your eyes.

I can say the same thing about A Twist Of the Wrist vol II for road racing motorcycles (which obviously I have read as well)