Race Driving Fundamentals: Heel & Toe
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Heel & Toe
08.45
| 00:00 | - One of the racing techniques that we'll need to master if we're driving a car with a conventional manual gearbox is heel and toe downshifting. |
| 00:07 | Before we cover what this technique is and how to apply it, let's discuss why it's essential. |
| 00:13 | This really comes down to the relationship between engine RPM and road speed as we go through the gears. |
| 00:20 | Let's start by considering what happens as we shift up through the gears. |
| 00:24 | We'll assume that we're in third gear at full throttle and we get to the shift point at 7000 RPM. |
| 00:30 | We back off the throttle, disengage the clutch and shift from third into fourth gear. |
| 00:35 | Due to the difference between the gear ratios, this means that the relationship between road speed and engine speed is also going to be different. |
| 00:43 | Depending on the specifics of your gear ratios when you're completed the shift into fourth gear, you might find that the engine RPM drops from 7000 to perhaps 5500 RPM when you release the clutch. |
| 00:56 | Since you're probably experienced this 1000s of times when driving a road car, I'm hoping that this should make sense to you. |
| 01:03 | While this isn't an issue on the upshift, it can cause us some problems when we downshift. |
| 01:09 | On the downshift, exactly the opposite situation occurs with our RPM and road speed and during the shift the engine speed needs to be increased so that when we release the clutch we have the correct engine RPM to match the road speed and our lower gear. |
| 01:24 | To use our previous example, if we were at 5500 RPM in fourth gear and we shifted down to third, the engine RPM would need to increase to 7000 for everything to nicely match. |
| 01:35 | The reason that this is important to understand is that if we don't do anything to achieve this rev match on the downshift, we risk what is referred to as compression locking the driven wheels. |
| 01:47 | Basically this is where the engine speed is forced to instantly increase as the clutch is released in order to achieve the correct engine speed to road speed relationship which can cause the driven wheels to under rotate or even lock up momentarily as the RPM is forced to climb. |
| 02:03 | At best, failing to match revs on the downshift will be uncomfortable and may unsettle the car. |
| 02:10 | At worst, we can end up with the car snapping into oversteer in the braking zone or even disappearing backwards into the kitty litter or a barrier. |
| 02:18 | If the track happens to be wet then this just magnifies all of the issues that not correctly matching revs can cause. |
| 02:25 | Now that we understand the problem that downshifting while braking can create, let's talk about the solution which is the technique of heel and toe. |
| 02:33 | This is where we brake as normal with our right foot but as we disengage the clutch with our left foot and perform the downshift, we use the heel of our right foot to blip the throttle, increasing the engine RPM to match the revs for the gear we're selecting before the clutch is released again. |
| 02:49 | It sounds simple and when you're comfortable with doing it, it is. |
| 02:52 | But as they say, the devil's in the detail and there's a lot that goes into getting the timing and the throttle application just right. |
| 03:01 | Heel and toe is something that takes a lot of practice to master but it's a must have skill so it pays to approach it with patience and the understanding that you may have to take a step backwards here in terms of lap times in order to take two steps forward. |
| 03:16 | The actual term heel and toe is slightly misleading because we don't actually brake with our toe and blip the throttle with our heel. |
| 03:24 | Generally the most comfortable and consistent way for people to heel and toe is by braking with the ball of the right foot and then blipping the throttle by rolling the outside of the foot onto the throttle pedal during the down change. |
| 03:37 | It's important to note that although this is the most common method it's not the only way and sometimes how the pedals are arranged from the factory means that you'll need to try different methods like swinging your heel across in order to see what works best. |
| 03:52 | Most importantly, it's what's comfortable for you. |
| 03:55 | Setting the pedals up correctly is also going to make heel and toe a lot easier. |
| 04:00 | If your pedals are adjustable, you want to set them up so that when you're hard on the brake pedal it's either flush with or slightly lower than the accelerator and this makes it easier to carry out the throttle blip comfortably and consistently. |
| 04:14 | On the other hand, if your brake pedal happens to sit much lower than the accelerator pedal when braking hard, we'll often see a reduction in brake pressure during the application of the throttle blip as the driver tries to reach the throttle pedal. |
| 04:26 | In terms of the practical side of mastering this technique, the good news is that this is something we can initially practice at home without using up precious track time. |
| 04:36 | Try sitting in your car and running through the initial braking phase first and then down changing, attempting to blip the throttle as you do. |
| 04:44 | Keep doing this until it starts feeling natural. |
| 04:47 | Once you're confident with the actions it's now time to give it a go in your road car. |
| 04:52 | Just be aware that it's actually considerably different to perform properly on the road because you won't be using anywhere near as much brake force as you would on the track. |
| 05:01 | This means that what you learn in your road car will be useful for building up the muscle memory of the physical action but you'll need to work on your brake modulation when you're next out on the track. |
| 05:11 | When you're able to consistently and reliably rev match on downshifts in your road car, it's time to commit to doing it on the track. |
| 05:20 | I say commit because we need to go to the track with the mindset that the day is going to be all about mastering this technique so leave your lap timer off and don't worry about your times. |
| 05:31 | Initially you probably won't be as fast as before when applying the heel and toe method and it'll get frustrating at times but it's important to stick to the process. |
| 05:40 | It'll soon become second nature with clean and consistent rev matches on the down change and you'll be wondering how you ever went without it. |
| 05:49 | While you're working on your heel and toe technique, there are 4 areas you're likely to make mistakes while you're learning. |
| 05:56 | The first two are very similar, either over blipping or under blipping on the shift resulting in a poor rev match. |
| 06:03 | Both of these situations are pretty easy to spot because you'll hear that your revs aren't matched when the clutch is released. |
| 06:09 | If you've over blipped then the engine RPM will be too high and you'll hear it quickly drop as the clutch is released. |
| 06:16 | Conversely if you've under blipped then you'll hear the RPM jump up as the clutch is released. |
| 06:21 | Since under blipping can have the same affect as not blipping at all, you may also notice the car tends to become unstable or unsettled when the clutch is released. |
| 06:30 | The next issue comes down to timing of the blip and in particular when to release the clutch in relation to when the blip is applied. |
| 06:38 | Of course if we blip the throttle and do nothing the engine RPM will rise and then just as quickly it'll drop away again. |
| 06:45 | Assuming you've got the blip correct, then you want to release the clutch as the RPM peaks. |
| 06:50 | The last area you're likely to go wrong is with modulating brake pressure during the downshift. |
| 06:55 | Multi tasking is tricky at the best of times so the natural tendency while you're learning to heel and toe is to reduce the pressure on the brake pedal as you blip the throttle. |
| 07:05 | Understandably if we reduce the brake pressure, we're no longer at the limit of the tyre's grip and this is not going to be great for our braking distances. |
| 07:14 | While we need to concentrate on trying to keep the brake pressure consistent throughout the shift we also need to be realistic about what's possible. |
| 07:21 | Even a data trace from a professional race driver will usually show a slight reduction in brake pressure during the blip so some of this will be unavoidable no matter how much you practice. |
| 07:33 | Major brake pressure changes should be easy to detect from the driver's seat because you'll feel the reduction in braking force. |
| 07:40 | Smaller brake pressure changes aren't so easy to feel though so this is where data analysis becomes an important part in helping your driving skills. |
| 07:48 | We'll be taking a closer look at this in an upcoming module. |
| 07:52 | In the next module we'll run through a practical demonstration of exactly how all of this works and once you've mastered the skill of heel and toe downshifting, you'll be able to brake later and more aggressively without unsettling the car in the braking zone. |
| 08:06 | This will translate to faster lap times and improved consistency. |
| 08:10 | To summarise, the heel and toe technique is an essential skill for anyone driving a manual gearbox car in order to drive smoothly on the track and avoid the chances of compression lock up. |
| 08:20 | This is something that can be practiced in the garage and on the street to a degree but a real world track scenario requires much harder braking and therefore will feel quite different as you roll your foot over from the brake pedal to the throttle. |
| 08:33 | With that in mind, it's important to set up the pedals for the best heel and toe feel when extremely hard on the brakes, not as you'd apply them on the road. |
