Top Drives approach to braking – Data analysis
Top Drives approach to braking – Data analysis
We all tend to class out cars on the way the accelerate and on the way they grip. But there’s little discussion on how a car brakes. And, in real life (mostly in competition, of course) it is a critical measure of a vehicle’s performance.
Reality is clear and stubborn. If a car accelerates and corners identically to other but has a braking advantage, it will be faster around a circuit. It will allow it to brake at a later point, and therefore, carry higher speed just before the curve.
But, how does Top Drives approach this? Are there really differences in between different cars, and how may this impact its performance? Let’s see it.
How to measure it
Normally, there are two methods to measure braking: one is braking distance and the other one is deceleration.
Below there’s a table (source: km77.com) of braking distances in several production vehicles.
Table 1: Real world braking distances – an example
As you can see, all comfortably over 10 m/s2 (over 1g, that is 9.8 m/s2)
What are the figures we can see in Top Drives? We are going to use the same metric (deceleration in m/s2) to compare results with real world.
The data logging
First, we need some data points. For that, I’ve used measurements from 0-100mph (Midlands 5) and from 0-100-0 mph (Midlands 7). It is obvious that deceleration time would be
100-0 decel=(0-100-0 time)-(0-100 time)
One assumption, a fair one, is that there’s no reaction time by the driver – as soon as the vehicle hits 100mph, brakes are applied to max pressure with no latency.
With that, a nice table can be created with some sample points
Table 3: Part of the data acquisition process
And then of course some deceleration figures can be extracted
Table 4: Deceleration figures in Top drives, finally!
This can be better visualized in a graphic:
Figure 1: It is clear there are three main braking profiles
It looks like there are three main groups:
- A 1st group in between 7 and 8 m/s2. These are traditional offroaders with heavy weight (e.g., Defender Works)
- A 2nd group in between 9 and 10 m/s2. This one includes mostly vehicles with standard and all surface tires (Macan being an exception)
- Finally, a 3rd group with ca 11 m/s2 and above. Here we’re talking about mostly vehicles with performance and slick tires + specific competition machines such as the 205 T16 EVO2 or the Lancia 037.
This can be observed if results are grouped by tire type:
Figure 2: Deceleration for offroad tires
Figure 3: Deceleration for All Surface tires
Figure 4: Deceleration for Standard tires
Figure 5: Deceleration for performance tires
Figure 6: Deceleration for slick tires
This kind of makes sense with regards to vehicles equipped with performance tires – i.e. achieving a decel of ca. 11 m/s2 is normal. However, I would have expected a much better behaviour from competition vehicles with slick tires vs “normal” vehicles with performance tires (e.g., the Zonda Revolucion there’s no way it would brake less than a Lotus Elise Sprint), and I would have expected standard tire vehicles to brake significantly better than they do here – check the real world example of the VW Arteon, with over 11 m/s2, whereas here would be flirting with the 9 m/s2 as the rest of the standards.
What can additionally be observed is that:
- Weight has an impact on braking distance. The champion among the cars I’ve tested is the Caterham Superlight R500, and other cars such as the Lotus 340R or the Elise Sprint fare quite well, too.
- ABS does not make a difference in the dry. We’ll come back to that afterwards.
- What does make a difference is the age of a vehicle. Normally, the older a vehicle is the worse it brakes, and here it is reflected in cars such as the Jaguar C-Type (worst performance among the sampled vehicles) or the Peugeot 402 Darl’mat, Abarth 100TC. My theory here is that in these cases Hutch just classifies these cars in one of the low-braking categories despite its tyres.
There are however more interesting facts:
- Updates do have an impact on braking distance. Let’s use the Lotus Elise Sprint and the Dodge Venom as examples – we can see that maxing a car, actually, worsens the braking distance / deceleration. This makes no sense, as the lighter a car is (all the other components being the same), the better it brakes. Hutch will need to take a look at this.
Figure 7: This does not make sense. Why maxing a car worsens its braking behaviour?
- In a car in three different states of tune there are marginal differences. In the example below (Golf GTI TCR), the one 233 brakes slightly better than its siblings. In reality, a 233 car shall brake identically to a 332, and slightly better than a 323.
Figure 8: Comparison in between different tunes in the same vehicle
In the wet
And, what happens in the wet? Yes, I’ve done some calculations too 😊
I’ve used Midlands 6 and 8 for this, with the same methodology. These are the results:
Table 5: Wet table
And these the deceleration figures
Table 6: Deceleration figures in the wet
And again, represented in a graphic:
Figure 9: Some cars see big degradation in braking distance in the wet!
What we can extract from here is:
- Tire type has massive influence in the braking distance in the wet. Note how slicks are heavily penalised, 4WD as in the 208 T16 R5 does not help (it shouldn’t)
- Normally, standard tires behave better, followed by all surface. Performance tires in some cars also do well, but in this case they are comparable to standards.
We can even assess how performance is degraded for some vehicles:
Figure 10: Look at what happens to the 208 – from being one of the best in the dry to be a complete disaster in the wet
And finally, we can extrapolate some degradation percentages
Figure 11: We can see some pattern in here with regards to tire mount, can’t we?
What does this graphic mean? It means that in the case of some cars with Std tires (Cadillac CTS, Mazda Cosmo and DS Numero 9), braking performance is only reduced 20% in the wet. In cars with slicks such as the 208 T16 R5 or the Zonda Revolucion, degradation is ca. 70%.
What can we learn from all of this?
- Braking distances / deceleration are divided in three main groups – looks like Hutch have three categories for braking and they assign vehicles to one or de other depending on several factors.
- In general, braking distances are consistent for performance tires, but I would have expected a bigger differentiation with competition cars (massively better) and standard cars with a better behaviour.
- Tires, Weight have the biggest impact on braking distance.
- Maxing a car in fact worsens its braking distance! This does not make sense and Hutch would need to do something about it.
- In the wet, there are correction factors applied depending on the vehicle’s tires. Standard tires are the best here, followed by all surfaces. Slicks are a disaster here, and offroad do not do much better.
In general, I think vehicles are grouped in categories instead of applying specific braking behaviours. i.e., whilst each vehicle has its own profile for acceleration, looks like braking performance fits into one category and sticks with it. We do not play Top Drives as per its real-world simulation correlation, but it is worth noting this – and Hutch has all this data through EVO!
Figure 12: Average deceleration profiles for different tires
Figure 13: Average deceleration degradation in the wet depending on tire mount
Thanks for reading through this – I hope this is useful to some, and more than happy to support with questions.
Challenge --> can you find the best braking cars? So far, what I found is the Caterham Superlight R500 in the dry and the Macan Turbo in the wet.
And finally, to @hutch, I hope you can appreciate the work that has gone into this. I’d love to expand it, but I’d need a deeper garage. A free choice of 5 legendaries would be really nice from you and would encourage me to keep doing this kind of work 😊