Race Driving Fundamentals: Brake Application
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Brake Application
08.55
| 00:00 | - Braking is one of the most common areas a novice driver will lose time on the racetrack so it's one of the most critical components of your driving to focus on. |
| 00:09 | Whether we're talking about lap time or consistency, having the correct brake application technique is crucial to setting you up for each phase of the corner. |
| 00:18 | The most common braking problems with a beginner driver come from braking too early and not braking hard enough. |
| 00:25 | This is usually a hangover from the sort of braking technique that we use on public roads coupled with a lack of trust in the ability of the car. |
| 00:34 | On the racetrack however, this simply costs us time so it's a habit that we need to get out of. |
| 00:40 | It sounds obvious but what we're trying to do is brake as late as we can into the corner and then use 100% of the available grip to slow the car down as quickly as we can. |
| 00:51 | Understandably we still need to be able to slow the car enough to get around the corner too. |
| 00:56 | While it sounds easy in theory there's a lot that goes into optimising our braking performance. |
| 01:01 | To get some perspective around this, let's compare braking data from a professional driver and an amateur. |
| 01:08 | In this example we can see that the pro driver is braking around 15 metres later than the novice but the peak brake pressure the pro is using is also substantially higher. |
| 01:18 | This allows the pro driver to control the brake pressure right on the threshold of lockup which allows the car to slow down much faster. |
| 01:26 | Ultimately this means the pro driver can still slow the car down to the required speed to allow it to turn into the corner. |
| 01:33 | But by braking later, and holding more speed through the early part of the braking phase, this technique saves almost 2/10th of a second and that's just on one corner. |
| 01:43 | Before we go any further, we also need to understand how a tyre performs when we're braking hard. |
| 01:49 | As we apply more pressure to the brake pedal, the tyre will get to a point where it slows and begins to slip or under rotate against the track surface. |
| 01:58 | This is a fine line because further brake pressure application will result in the tyre locking and if you've ever experienced a big lockup, then you'll know that the car won't slow down as quickly with a locked wheel. |
| 02:10 | A subtle aspect of this is that if we could plot the braking force generated by the tyre as the tyre begins to under rotate, then we'd find that we get maximum braking force with a slight slip of perhaps 5%. |
| 02:22 | In other words the tyre is rotating around 5% slower than the road speed. |
| 02:27 | Every tyre will behave differently so the exact number isn't really the point here. |
| 02:33 | What's important to understand is that it's possible to slow the car down faster when the tyre is actually under rotating. |
| 02:40 | It's equally important to understand though that this is an advanced concept that even professional drivers struggle to do consistently. |
| 02:47 | To start with, you're best to focus on just optimising your braking without locking a wheel. |
| 02:53 | Now let's consider the braking sequence. |
| 02:56 | This actually starts before we even consider touching the brakes because we'll be approaching the braking zone at full throttle. |
| 03:02 | It's easy to overlook but how we transition from the throttle to the brake is also important. |
| 03:08 | What we want to do is make this transition as quickly as possible. |
| 03:12 | This will minimise the amount of time between accelerator and braking. |
| 03:16 | If the car is travelling at 200 km/h, it's covering 56 metres every second so if it takes you a 10th of a second to get from the throttle to the brake pedal the car has travelled almost 6 metres. |
| 03:29 | The quicker we can make this transition, the longer we can stay at full throttle and the less time we're going to lose. |
| 03:36 | Once we're off the throttle we can now begin the brake application and we're wanting to quickly and aggressively achieve enough brake pressure to be just short of locking up. |
| 03:45 | Just like the transition from the throttle to the brake pedal, the car is covering a lot of ground as we're applying the brake pressure so the faster we can achieve maximum braking pressure, the less distance the car will travel in the braking zone. |
| 03:58 | While we want to be aggressive with our brake application, this doesn't mean that we can treat the brake pedal like a switch. |
| 04:05 | Every car will have an optimal rate at which we can apply the brake and this is down to the natural pitch frequency of the chassis which is a factor of the suspension design and spring rates. |
| 04:16 | This is well outside the scope of our course but essentially a stiffly sprung purpose built racecar with high downforce will tolerate a much more aggressive brake application than a softly sprung modified road car. |
| 04:29 | The specifics of our car do come into play here with how aggressive we can be. |
| 04:34 | But you'll find that it's almost always a case of trying to make the initial brake application more aggressive than you currently are, not less and this is most likely what you're going to need to focus on. |
| 04:46 | Once we've reached maximum braking pressure for a car with no downforce, we're going to hold a reasonably consistent pressure to keep the car at the threshold of grip. |
| 04:55 | On the other hand, for a car with high downforce, the available grip will reduce as the speed drops so we'll see the brake pressure initially peak before smoothly tapering down as the car slows and the downforce reduces. |
| 05:09 | Of course in either situation some modulation of the brake pressure may be required if you begin to lock a wheel. |
| 05:16 | The last part of the braking process is how we release the brake pedal. |
| 05:20 | This might sound straightforward but this is actually one of the more complex parts of the braking sequence which can have a significant influence over the car's balance and how it'll turn into the corner. |
| 05:32 | Since this is a topic in its own right, we're going to deal with it in a separate module. |
| 05:37 | The sequence I'm describing so far will be ideal for a big braking zone where the car is at high speed and approaching a slow corner but the braking technique will depend on the type of corner we're approaching and how much speed reduction is required. |
| 05:51 | For example, if we're approaching a fast corner that just requires a little speed to be bled off, a sharp aggressive brake application is likely to unsettle the car which is exactly what we don't want. |
| 06:03 | In this situation we want to apply the brake pedal more slowly and with less peak pressure. |
| 06:09 | Building up the pressure and releasing it like this limits the weight transfer around the car which can aid car balance and prevents the car from becoming unsettled as we turn into the corner. |
| 06:19 | This technique is often referred to as brushing the brakes and if we compare the brake pressure trace with our previous example you can see how different it is. |
| 06:28 | Once we understand what we're going to be doing in the braking area, we need to decide on a suitable point to brake and this is where we want to be using a braking marker. |
| 06:37 | This can be any visual reference like a marker board, the end of a fence, a piece of curbing or a change in track surface. |
| 06:44 | Just make sure that you're choosing something that isn't going to change location like a shadow from a tree for example. |
| 06:51 | The importance of a braking marker is that it gives us a consistent reference for our braking lap after lap. |
| 06:57 | It also provides a reference when we're pushing our braking later to find the ideal braking point. |
| 07:03 | For example if we brake at a certain point and find that we've overslowed the car, we can use the same reference on the next lap and simply push the braking point out by a car length at a time until we creep up on the optimum point. |
| 07:15 | I've already mentioned the most common beginner mistakes of braking too early, not building pressure aggressively enough and not using enough peak pressure but once a driver starts building confidence we do tend to see a new set of mistakes boiling to the surface. |
| 07:30 | The biggest issue that creeps in at this point is braking too late. |
| 07:34 | There's a fine line here as the car can only go around the corner so fast before you exceed the available grip so we need to get it down to this maximum speed in the braking zone. |
| 07:45 | The danger here is that we'll still be trying to slow the car when we reach the turn in point and this can result in the car understeering at turn in because we're now asking too much from the front tyres. |
| 07:56 | The problem is that it can be very easy to blame the chassis and suspension setup instead of recognising that the issue actually lies in the fact that we're braking too late. |
| 08:07 | To summarise this module, braking is one of the most critical components of your driving technique and something that takes time and practice to perfect. |
| 08:16 | Beginner drivers tend to brake too early and it takes serious effort to start pushing the braking later and later into a corner by effectively using braking markers but this is where we're going to find plenty of time over a full lap once we get it right. |
| 08:31 | Once confidence builds, drivers tend to start braking too late so a balance needs to be found and it's important to recognise that most corners and most cars are different and a one technique fits all approach just isn't going to cut it. |
| 08:45 | This is something that needs to be felt out each time you arrive at a racetrack or make big changes to your car setup. |
