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Practical Corner Weighting: Knowing Whats Wrong on Track

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Knowing Whats Wrong on Track

10.22

00:00 - One of the key skills that forms part of this course and is critical to corner weighting your car is actually analysing the performance of the car on the racetrack and knowing essentially what it's doing wrong.
00:12 So in this module we're going to dive into some of those aspects.
00:15 We've brought out RaceCraft Toyota 86 here to Highlands Motorsport Park and we're going to head out on track shortly and we're going to have a look at the different ways we can analyse the performance.
00:26 The keys here, first of all we're going to be looking at braking performance.
00:30 What we ideally want is for the car to brake in a nice straight line and we want to make sure that it's not consistently locking one individual wheel.
00:40 Now in the case of our Toyota 86 this does use ABS so this becomes a bit of a moot point but that's not to say that we can't still learn something from the way the car brakes.
00:50 Even with an ABS equipped car, if there is an imbalance that's affecting the braking performance, we're likely to find that the car will tend to pull on the steering wheel in one direction consistently when we are braking.
01:02 That's what we're going to be looking for.
01:04 When we are performing this test, we want to make sure ideally that it's from high speeds so we are really giving the braking system a good test and we also want to make sure that we are braking in a straight line.
01:16 If we're trying to brake while still turning or for that matter we're on uneven ground this is definitely going to result in one corner of the car braking better than the other.
01:26 For this part of our test we're going to be concentrating on the braking performance of the fastest part of the track where we're doing around about 200 km/h, braking towards the bus stop.
01:36 The next aspect we're going to test is our steady state handling balance and what I mean by this is mid turn.
01:43 So at this point in the corner we're not going to be influenced so much by driver induced handling problems.
01:49 As we've already discussed in the body of the course, it's very easy for the driver to induce understeer at corner entry by the way they brake into the corner or trying to enter the corner too fast.
02:00 Here we're going to be looking at the handling balance through a moderate speed right hander known as the southern loop.
02:05 This is a very long corner that almost goes through a full 180° and mid corner we're going to be able to feel the balance of the car, we're going to be able to play with both the steering as well as the throttle and feel if the car has good balance, if it's feeling nice and stable and if whether it has a tendency towards either understeer or oversteer.
02:25 The next part of our testing's going to be looking at how the car handles to the left and to the right.
02:31 In other words, can we generate equal cornering force in left hand and right hand corners? Now specifically here we're going to have a look at the way the car handles through a section of the track known as the S'.
02:42 This is a left hand entry followed by a low speed right hand and then a low speed left hand corner.
02:49 Now this can be backed up as well by data if you have it available.
02:53 In particular a great way of analysing this is to use a GG diagram or the traction circle as it's also known.
03:00 This allows us to plot the lateral G force in relation to the longitudinal G force and essentially from that diagram we can quickly see if the car can generate equal cornering forces to the left and to the right.
03:12 A word of caution when you are using a GG diagram though, particularly with cars that incorporate down force, we need to be mindful of the cornering speed because of course as the cornering speed increases, a car that uses downforce can generate more cornering force so just take that into account with your analysis.
03:31 The next section of track we're going to analyse is turn 13 which is a high speed left hander, leading towards a hairpin corner.
03:39 Now this is a corner that's taken at around about 150 to 160 km/h in our particular car.
03:45 And this can be a key corner, if we've got good handling balance here and the driver has confidence, this can allow the driver to use more throttle through this corner, holding more speed and ultimately improving the lap time.
03:58 The last corner we're going to analyse is turn 22.
04:02 Which is the turn that leads onto the main front straight.
04:05 This is a corner that we're taking in fourth gear and it demands a lot of respect because there is a concrete wall on the outside of the corner.
04:13 So if we go in too fast into this corner or we don't have good balance of the car and it wants to snap into oversteer, or alternatively understeer, we risk putting the car into a wall.
04:23 If we get this right though, it does lead onto quite a long straight so any improvements we get in cornering speed here will improve our lap time dramatically the whole way up to the next corner.
04:35 Now that we know what we're going to be analysing, let's head out onto the track and see what our existing setup gives us.
04:41 - Alright we've done a couple of laps here just getting our tyres up to temperature so that we can get a normal representative test and I'm just coming onto the front straight and we'll come into our first braking zone coming up to the bus stop.
04:53 In here, what I'm going to be doing is just being sensitive to what the steering wheel is doing while I'm braking.
04:59 This will allow me to feel if the car is tending to pull in one direction or another.
05:04 Alright just coming up to our braking marker now, nice and straight, maximum braking force and the car's pulling up perfectly straight so it's not doing anything I'm concerned about there.
05:16 It's nice and straight and controllable so I'm pretty happy with that.
05:18 Next we've got the southern loop, now this is a nice long corner so we can really test the balance out under steady state conditions and here I've got a slight tendency towards understeer.
05:30 I'm not unhappy with that though and importantly the car feels nice and stable and predictable.
05:35 So I'm pretty happy here with how everything feels.
05:38 Now we're coming up to the S' so we're looking for consistent handling through the left hand entry, the right hand section through the middle and then finally the left hand exit.
05:48 Since this is a slow speed section I can easily push the car into oversteer with too much throttle but the balance felt quite consistent in both directions so there's not too many concerns through that particular section of the racetrack.
06:02 OK we're coming up towards turn 13 and we're going to set up on the right hand side of the track before turning in and looking for our apex.
06:10 The whole way through this corner the car just feels a little unstable, like it wants to move around and this isn't providing a lot of driver confidence.
06:19 So this is potentially an area that we can work on there.
06:23 Alright we're coming up towards turn 22, that last corner we wanted to analyse leading onto the front straight.
06:29 On the entry to this we also need to get through the hairpin at the museum.
06:34 Getting a good exit here is critical to maintaining good car speed and getting a good run towards turn 22.
06:40 Coming up to our braking point now, we just use a little dab on the brakes and we can turn it in, hitting the apex curbing across the inside of the corner then running wide out towards the pit wall.
06:51 To be fair, that actually felt really good, the car felt nice and stable and that helps inspire driver confidence.
06:57 Alright let's head back into the pits now and we'll see what we've learned.
07:01 Alright we've finished our track session and we'll just go over what we've learned there.
07:06 First of all there's not obvious or dramatic handling problems with the car, it's actually pretty well balanced as it is right now.
07:13 In particular going over those aspects we wanted to focus on, the car brakes really nicely in a straight line, it actually has always braked very well, even with road car ABS which sometimes can be problematic on a racetrack.
07:26 Going through our southern loop corner there, and this is a corner as I mentioned, we can check the steady state handling of the car and the car balance is pretty good there.
07:36 We are in and out of the throttle a little bit just finding the limit of adhesion there and there is a slight tendency towards understeer.
07:43 But particularly through that corner with a concrete wall on the outside of the corner, this actually inspires a reasonable amount of driver confidence.
07:50 If we've got oversteer through that corner, this is going to require a little bit more driver skill in order to catch that slide and make sure the car doesn't end up into the wall.
08:00 So now particularly problematic in that respect.
08:04 The next section of the track that we went through there is the S'.
08:08 Relatively low speed corner, we've got the left hand entry the right hand corner and then the left hand that leads us out underneath the bridge.
08:16 Now we do need to understand here of course because this is a low speed corner, we're taking this in third gear, we've essentially got more torque than we can put to the track so regardless of our corner weighting, it's easy to provoke a slide if we're a little aggressive on the throttle.
08:31 That's a driver induced handling issue rather than a balance issue though.
08:35 Ultimately though the car feels really good through that section of corners.
08:39 We can also check our GG diagram and see how the car is responding.
08:44 Looking at our GG diagram, not just over that section of corners but over the complete track, we can see that we are generating essentially identical cornering forces in both left hand and right hand corners.
08:56 The next section of track that we analysed, turn 13 our fast left hand corner, and this is about the only area of the track where I see that there's probably some potential for improvement here.
09:09 This is an area where the car felt like it wanted two swap ends, feels like a lack of grip from the rear end of the car and this means that there's not enough confidence from me as a driver to be able to use more throttle.
09:22 Particularly if this is relatively high speed, we obviously risk a high speed spin which is not going to be ideal.
09:29 So this is an area that we definitely want to focus on potentially.
09:33 The last section of track that we looked at there, turn 22, coming onto our front straight and as I discussed this is a corner that demands respect from the driver.
09:43 That being said, the car felt really balanced there, quite neutral, again a very slight amount of understeer if anything but nothing that's going to prompt us to make any changes.