Handbraking on corners (automatic gearbox, GT)

[brigadir]

Since the car understeers, I'm trying to turn it in slow corners with hand brake. Here are the questions I can't find straightforward answer for:
- Is it good idea in general? At least according to some articles on internet, looks like a working approach (ex.

).
- How the transmission handles rear wheels lock in this case? Does it have some kind of algorithm to loose torque converter and reduce the torque? Or it just keeps feeding the rear wheels with torque according to accelerator pedal? Would be helpful to get any official info here.
- In case it's good idea to use handbraking, what cautions to consider? Will the car tell me if something will start to overheat?

Also interesting what are the best practices here. Trying it couple of times I found the car isn't very obeying, so it's hard to predict the turning and dose the braking. The car is almost stock 2015 GT with 6R80 gearbox, with only aftermarket coilovers from ISC.

Thanks in advance for answers/tips. Forgive me if the question is dumb, just stepped into this topic.

 

[mwjscn]

I'd suggest to try trailbraking into the corner before advising someone to rip the handle.

 

[Vettel-ish]

Trailbrake for sure. Aka keeping around 20% pressure on the brakes into the apex. Keeps the nose planted and helps turn in. Muscle cars like this.

This sounds dangerous.

 

[JDee]

That video is of a front/4 wheel drive car, that's a totally different animal than Mustangs. They're also on a loose surface. That's a totally different animal than what we do on road courses.

If you're ice racing or rallying on gravel in a front wheel drive car the handbrake works on extremely sharp corners. In a 4 wheel drive car you can use the handbrake to help set the car up going into the corner, but it's quickly released so you can get on the gas to exit the corner. I've done both disciplines in both FWD and 4WD cars and used the hand brake very rarely and then only on the tightest of corners. It works best with FWD cars.

On pavement circuit racing it's not fast at all, it just kills your momentum. It also causes huge unpredictability in what the car will do. I road raced an FWD car back in the day and It is just not done, it provides no advantage at all.

And with a rear wheel drive car? Absolutely not going to be quick and I would guess that you would quickly run into serious problems from doing it. When I was a cop we used to use the parking brake to spin the car 180 degrees in not much more than its own length. However, after about 6 of those parking brake 180's the rear brakes would be fairly much destroyed, the shoes tended to warp and the linings disintegrated.

There is no serious driving instructor teaching road course driving who would suggest such a thing. In 55 years of being involved in road course driving I have never heard of anyone doing that.

 

[TMSBOSS]

Welcome to the site!

Can you post a build thread so folks can see what you have. This will make suggesting changes a bit easier, and better informed.

The first thing I would consider when looking to reduce under steer is more steering. Specifically better, larger front tires and wheels. I would forget about using the hand brake to bring the rear around. What will likely happen is the rear will come around, all the way around. This is great for drifting, not for speed.
Most manufacturers build under steer into their cars for street use. It’s safer and easier for the beginner to handle. Unfortunately as you have found, it’s not fast. I would be cautious of “Articles on the Internet”. Fact and opinion become blurry quickly on the net. Rear braking “May” give you the appearance better car control when in reality all you are doing is making rear grip worse in an attempt to balance the car. Better to improve on what you have. Making what you have, in this case rear grip, worse.

Give us a chance to see what you have now and I would expect folks who have worked through the same challenges will have some specific advice to improve your ride. I would bet tires and wheel will make the most improvements.

Again, welcome to the site.

 

[brigadir]

Welcome to the site!

Can you post a build thread so folks can see what you have. This will make suggesting changes a bit easier, and better informed.

The first thing I would consider when looking to reduce under steer is more steering. Specifically better, larger front tires and wheels. I would forget about using the hand brake to bring the rear around. What will likely happen is the rear will come around, all the way around. This is great for drifting, not for speed.
Most manufacturers build under steer into their cars for street use. It’s safer and easier for the beginner to handle. Unfortunately as you have found, it’s not fast. I would be cautious of “Articles on the Internet”. Fact and opinion become blurry quickly on the net. Rear braking “May” give you the appearance better car control when in reality all you are doing is making rear grip worse in an attempt to balance the car. Better to improve on what you have. Making what you have, in this case rear grip, worse.

Give us a chance to see what you have now and I would expect folks who have worked through the same challenges will have some specific advice to improve your ride. I would bet tires and wheel will make the most improvements.

Again, welcome to the site.

Thanks for the answer, as well as to the other commenters. The car is pretty stock 2015 GT with automatic transmission. Even with stock size tires 255x40x19. I only have put coilovers from ISC.
So, I got the recommendations regarding handbraking. Will try practicing trailbrake instead.
Regarding car adjustments, looks like makes sense to go with more negative camber, since the coilovers have camber plate. And the next step - wider tires?

 

[TMSBOSS]

Definitely wider, sticky tires. If it’s in your budget consider a set of wheels to go with the tires. A square set up, all corners on same size wheels and tires is beneficial if you are considering running the track. It will give you a wider tire up front as well as the ability rotate all four corners extending tire set life. Add in some camber depending upon your intentions for the car.
What are your plans for the car? Fun street cruiser with better grip. A part time track car. Full time track beast. It can be a fun, slippery slope. Enjoy the ride!

 

[Dave_W]

No. Just no. That video is from Team O'Neil, a rally school where they mostly teach gravel driving in FWD cars. As mentioned in the video, trying that in a RWD car can stall the engine with a manual, or cause wear on an automatic - the torque converter should keep the engine from completely stalling but I don't believe there's any logic connection between rear wheel speed and transmission control. However, it may confuse the stability / traction control systems. Plus, a big part of that technique is getting the powered front wheels to pull you through and out of the slide, which you can't do in RWD.

From years of experience, many times the complaints of corner entry understeer by autocross novices is due to overdriving the corner, trying to brake too late, and generally not slowing enough. Instead of looking well ahead, using the brakes to slow down to the proper entry speed in a controlled manner and then smoothly turn down to the apex, they jump on the brakes too late and too hard and then crank in a bunch of steering wheel. This creates huge understeer on entry; the slipping (but not locked) front tires eventually help to slow the car to the point they regain full traction, at which time they turn the nose into the corner (with the driver still using too much steering) and the car changes from understeer to oversteer mid-corner. That prevents early throttle application on corner exit, which means you're slower down the next straight than a driver who executed the corner correctly.

Question for you - do you feel "surprised" by the corners / gates during the run, or are you relaxed? Are you making steering changes because the corner / gate isn't where you "expected" it to be? These are common signs of not loking far enough ahead. Novices tend to look just over the car hood, and get "target fixation" staring at each apex cone until the car is past it. If you're looking at things 1/2 second in front of the car, human reaction time and car inertia mean there's pretty much nothing you can do to to change the car's position from hitting a cone that close.

Look ahead. No, further ahead. You need to be thinking / scanning about 2 seconds in front of the car. First, walk the course until you can draw it from memory - you don't need to memorize every cone, just the important ones that define the arc of each turn. Second, at the time you hit the brakes to slow for a corner or start to turn the steering wheel, you should have looked ahead enough to identify the both the corner apex and exit. Without doing that, how do you know exactly how much to slow the car (or if you have to) and turn the wheel? Before you turn into a corner, you should already know how much you need to turn the wheel to create the correct path for the car to smoothly get through the corner - your steering wheel input should be smoothly increasing to the apex and then smoothly unwinding to the exit (with smooth application of throttle). Smooth is fast.

Once you know that you're not overdriving the corner entry, if you still have corner entry understeer you can use your tuning adjustments - tire pressures, anti-roll bars, shock settings, springs, roll center heights, etc. - to adjust the balance.

Since you're using aftermarket coilovers, where do you have the ride height set? With a McPherson strut front suspension, lowering it too much can change the front roll center for the worse. If it's 1" or more lower than stock, try raising it up to just 1/2" under stock and see how it feels.

 

[Bill Pemberton]

You are lots of great information and since I have been lucky to go to 10 Professional Driving Schools because of where I worked , not a single one advised ever using the emergency brake. Learn to trailbrake as many advised and " Welcome to TMO!" Feel free to ask questions, we all understand the passion and the excitement getting on track can inspire.

 

[brigadir]

Definitely wider, sticky tires. If it’s in your budget consider a set of wheels to go with the tires. A square set up, all corners on same size wheels and tires is beneficial if you are considering running the track. It will give you a wider tire up front as well as the ability rotate all four corners extending tire set life. Add in some camber depending upon your intentions for the car.
What are your plans for the car? Fun street cruiser with better grip. A part time track car. Full time track beast. It can be a fun, slippery slope. Enjoy the ride!

The car is for daily drive, sometimes on bad roads. So, I’m sticked to soft springs and stock ride height. I go to a track time to time, with intent to improve driving skills there, and because of enjoying it of course
My goal is to learn how to drive it correctly on track without spending big buck on it

 

[brigadir]

No. Just no. That video is from Team O'Neil, a rally school where they mostly teach gravel driving in FWD cars. As mentioned in the video, trying that in a RWD car can stall the engine with a manual, or cause wear on an automatic - the torque converter should keep the engine from completely stalling but I don't believe there's any logic connection between rear wheel speed and transmission control. However, it may confuse the stability / traction control systems. Plus, a big part of that technique is getting the powered front wheels to pull you through and out of the slide, which you can't do in RWD.

From years of experience, many times the complaints of corner entry understeer by autocross novices is due to overdriving the corner, trying to brake too late, and generally not slowing enough. Instead of looking well ahead, using the brakes to slow down to the proper entry speed in a controlled manner and then smoothly turn down to the apex, they jump on the brakes too late and too hard and then crank in a bunch of steering wheel. This creates huge understeer on entry; the slipping (but not locked) front tires eventually help to slow the car to the point they regain full traction, at which time they turn the nose into the corner (with the driver still using too much steering) and the car changes from understeer to oversteer mid-corner. That prevents early throttle application on corner exit, which means you're slower down the next straight than a driver who executed the corner correctly.

Question for you - do you feel "surprised" by the corners / gates during the run, or are you relaxed? Are you making steering changes because the corner / gate isn't where you "expected" it to be? These are common signs of not loking far enough ahead. Novices tend to look just over the car hood, and get "target fixation" staring at each apex cone until the car is past it. If you're looking at things 1/2 second in front of the car, human reaction time and car inertia mean there's pretty much nothing you can do to to change the car's position from hitting a cone that close.

Look ahead. No, further ahead. You need to be thinking / scanning about 2 seconds in front of the car. First, walk the course until you can draw it from memory - you don't need to memorize every cone, just the important ones that define the arc of each turn. Second, at the time you hit the brakes to slow for a corner or start to turn the steering wheel, you should have looked ahead enough to identify the both the corner apex and exit. Without doing that, how do you know exactly how much to slow the car (or if you have to) and turn the wheel? Before you turn into a corner, you should already know how much you need to turn the wheel to create the correct path for the car to smoothly get through the corner - your steering wheel input should be smoothly increasing to the apex and then smoothly unwinding to the exit (with smooth application of throttle). Smooth is fast.

Once you know that you're not overdriving the corner entry, if you still have corner entry understeer you can use your tuning adjustments - tire pressures, anti-roll bars, shock settings, springs, roll center heights, etc. - to adjust the balance.

Since you're using aftermarket coilovers, where do you have the ride height set? With a McPherson strut front suspension, lowering it too much can change the front roll center for the worse. If it's 1" or more lower than stock, try raising it up to just 1/2" under stock and see how it feels.

Thanks for explanation. Regarding my feelings - mostly there’s not a surprise, but disappointment that the car is too slow on slow corners. It feels like I already have slowed the car enough but it still understeers. I’m pretty sure I do them not well especially on series of opposite corners, but it’s another topic to learn. Also what’s noticeable because of lack of practice - it’s hard to find the limit when entering the corner, so sometimes I enter too slow, sometimes to fast, sometimes not at perfect trajectory. I’ll consider your advices.
Regarding the coilovers - ride height is stock. I set the shocks stiffness to 80% stiff for track. The next step I plan - to adjust camber. Lowering the car would be a difficult task because it’s needed to remove rear struts to access the thread on the springs, so I assume not to do it.

 

[Dave_W]

I assumed you were talking about autocross, only because I would never think to try using the handbrake at track speeds. Can you clarify if you are doing autocross or track days, or something else?

Don't be too hard on yourself - everyone is slow when they're starting out. It takes seat time and practice to build your skills. If you're doing events with other drivers, ask for ride-alongs with experienced drivers, and for instructors to ride with you. Go to as many events as you can to get seat time.

Practice looking ahead, driving "the line" through corners, and using smooth inputs on the street. At legal speeds, of course.

And most importantly, remember to have fun.

Basic "racing line" explanation - an important point is that the minimum speed of the "racing line" is slower than the "geometric line" but getting back to the gas earlier makes up for it

How the "racing line" can change based on corner type

Ross Bentley (famous racing instructor & author - check out more of his Speed Secrets) talking about braking and corner entry, and looking ahead

 

[mavisky]

Step #1 get a good alignment. Step #2 get better tires. If you're going to be expecting the car to have crisp turn-in you'll need to be willing to sacrifice some tire wear for that turn in. But, before that you have to sit down and level set with yourself on your priorities. Are you willing to sacrifice some of the daily drive-ability of your alignment and tire wear for better on track performance?

 

[brigadir]

I assumed you were talking about autocross, only because I would never think to try using the handbrake at track speeds. Can you clarify if you are doing autocross or track days, or something else?

Don't be too hard on yourself - everyone is slow when they're starting out. It takes seat time and practice to build your skills. If you're doing events with other drivers, ask for ride-alongs with experienced drivers, and for instructors to ride with you. Go to as many events as you can to get seat time.

Practice looking ahead, driving "the line" through corners, and using smooth inputs on the street. At legal speeds, of course.

And most importantly, remember to have fun.

Basic "racing line" explanation - an important point is that the minimum speed of the "racing line" is slower than the "geometric line" but getting back to the gas earlier makes up for it

How the "racing line" can change based on corner type

Ross Bentley (famous racing instructor & author - check out more of his Speed Secrets) talking about braking and corner entry, and looking ahead

Thanks for the videos. The track is pretty small: https://www.autodromomabed.com/circuitos.php?sec=CircuitoResistencia
So, at least for me, the slow corners are the main exercise. It’s funny to watch how Miatas and Minis dominate all sorts of high performance cars there

 

[brigadir]

Step #1 get a good alignment. Step #2 get better tires. If you're going to be expecting the car to have crisp turn-in you'll need to be willing to sacrifice some tire wear for that turn in. But, before that you have to sit down and level set with yourself on your priorities. Are you willing to sacrifice some of the daily drive-ability of your alignment and tire wear for better on track performance?

Sadly I need the car for daily drive as well. So my goals aren’t for high absolute numbers, rather for improvements in driving skills. I’ll apply modifications that don’t hurt street drive and would not cost a lot