Numbers like ‘1000HP’ and ‘100 PSI of boost’ catch our attention the most when it comes to motorsport builds as we can easily understand what they mean, but brake setups, while being equally if not more important, take a backstage role by comparison. For most, admittedly, it is much harder to get excited about figures or terms like ‘380mm’ and ‘staggered-piston design’, at least it is until you understand what it all means...
Use ‘PODCAST75’ for $75 off your first HPA course here: https://hpcdmy.co/hpa-tuned-in
In this interview with Phil Stubbs of Alcon Brakes, we’re going to take a look at why stock brakes on a production-turned-race car are terrible on track and what aspects you need to consider when looking to bin your OEM discs and calipers for something more effective.
Slots and gloves plus caliper and disc size in relation to braking performance are discussed along with airflow requirements, where sliding calipers braided brake lines sit when it comes to brake feel, plus on the other end of the spectrum what carbon-carbon brakes are vs carbon ceramic and what their weaknesses are compared to cast iron.
What is actually happening when you are bedding your brakes and the importance of doing that process correctly is also touched on, along with how in the motorsport world, companies like Alcon and similar offer pre-bedded brake packages, which save race teams time and potential inconsistency of doing it themselves on a race weekend when they should be focused on car setup and increasing driver confidence.
Numbers like ‘1000HP’ and ‘100 PSI of boost’ catch our attention the most when it comes to motorsport builds as we can easily understand what they mean, but brake setups, while being equally if not more important, take a backstage role by comparison. For most, admittedly, it is much harder to get excited about figures or terms like ‘380mm’ and ‘staggered-piston design’, at least it is until you understand what it all means...
Use ‘PODCAST75’ for $75 off your first HPA course here: https://hpcdmy.co/hpa-tuned-in
In this interview with Phil Stubbs of Alcon Brakes, we’re going to take a look at why stock brakes on a production-turned-race car are terrible on track and what aspects you need to consider when looking to bin your OEM discs and calipers for something more effective.
Slots and gloves plus caliper and disc size in relation to braking performance are discussed along with airflow requirements, where sliding calipers braided brake lines sit when it comes to brake feel, plus on the other end of the spectrum what carbon-carbon brakes are vs carbon ceramic and what their weaknesses are compared to cast iron.
What is actually happening when you are bedding your brakes and the importance of doing that process correctly is also touched on, along with how in the motorsport world, companies like Alcon and similar offer pre-bedded brake packages, which save race teams time and potential inconsistency of doing it themselves on a race weekend when they should be focused on car setup and increasing driver confidence.
Arguably one of the most common areas we see problems with a modified car when it's taken out onto the racetrack is with the performance of the braking package. It's really common, particularly with a factory brake package, to find that it just can't handle the heat that's generated out on the racetrack with sustained heavy braking into multiple corners. So this is where a lot of enthusiasts will look at upgrading their brake package, and we're here with Phil from Elcon to find out a little bit more about what goes into your considerations when it comes to these brake upgrades. Welcome to High Performance Academy's Tune In Field Report podcast series.
Speaker 1:In these special midweek episodes we look back through our archives to find the best conversations we've had through years worth of attending the best automotive events across the globe. We've pulled the audio from these tech filled interviews with some of the industry's most well known figures and presented it in podcast format for you to enjoy as a quick hit of insider knowledge. So, phil, for a start let's just talk about where the limitations lie in a production brake system. Obviously, a production car is designed predominantly for use out on the road and obviously on the track we're generating a lot more heat. So where are the problems we sort of see with that brake package when the heat generated starts to become excessive.
Speaker 2:Well, as you say, the problems are really in the heat capacity of the system. There's not enough mass in a stock rotor to handle multiple high energy braking events. And then also the friction material itself is designed to be quiet and to work well at low temperatures and just around town, and generally they don't hold up to the type of abuse you'd put on a racetrack.
Speaker 1:So basically, the disc, the rotor, cannot get rid of the heat fast enough, getting heat put into it faster than it can reject that heat. Plus, you've got the friction material that's not designed for a road car to work at those elevated temperatures.
Speaker 2:in a nutshell, Exactly yes, and the calipers, too, are not designed for the high temperatures either.
Speaker 1:Alright, so there's multiple areas that we need to focus on here, so let's just work through the system. So the first, of course, is a larger rotor. So can you talk us through the benefits of moving to a larger rotor, both in terms of diameter and thickness?
Speaker 2:Yeah, so if you increased the size of the rotor, then you're automatically getting more brake torque, which is first of all most important. A bigger rotor will generally cool better. You'll have a good racing rotor will be designed to pump air through it so it gets rid of the heat quickly. And then, in terms of the thickness of the rotor, again, that can give you thermal mass, additional thermal mass to keep everything under control and also help with the rejection of the heat.
Speaker 1:Now, in this instance, is it really a case of bigger is simply better and you want to go with the largest diameter rotor that you can physically fit within the rim size you're running?
Speaker 2:It really is for a brake rotor? Yeah, because it's basically free brake torque. The bigger rotor you put in, the more brake torque you'll get.
Speaker 1:It's important to mention, aside from your Elkon products here, as usual in most race applications that even with a large diameter rotor you're still going to have to augment that with airflow or cooling ducts to the brake rotor to try and help with that heat rejection.
Speaker 2:Absolutely. Yeah, that's really key, because the brake rotor isn't going to cool particularly efficiently on its own. It's got to have some air delivered to it in the right place to actually get that airflow through the whole system.
Speaker 1:Alright, so once we're dealt with the rotor and we're going to come back and talk a little bit more about the materials in a second but the other aspect here is of course the brake caliper itself and a lot of production cars we see on a cheaper level a slider style single piston caliper or dual piston calipers, and we've got four, six and eight piston calipers. Is it again a case of more is better, bigger is better? With the caliper is a little bit more to consider.
Speaker 2:It's not quite that simple with the caliper. One of the important things is the stiffness of the caliper. A sliding caliper isn't particularly stiff and what you want to do is all of the effort that your foot is putting into the brake pedal needs to go into clamping that rotor. So a stiff caliper is important. The other thing is the pad itself, the pad area. A larger pad area is going to give you more wear resistance and it's also going to, you know, spread the energy over a larger area.
Speaker 1:So when you say, spread the energy over the larger area there you're sort of talking about versus a small pad and a large pad you're basically putting less heat into that larger pad area.
Speaker 2:Exactly so. We calculate the energy per unit area for a brake system and it's based on the weight of the vehicle, how fast it's going to go and the other parameters of the vehicle itself.
Speaker 1:I'll just come back a bit as well. You said about the stiffness of the caliper and I just want to elaborate that on that because it might not have been 100% clear. And this is sort of the same reason why we also moved to a braided brake line, taking out any flex there so that the pedal feel to the driver is superior. They've got more feel of what's actually happening, so they've got more control over the brakes. Is that fair to say?
Speaker 2:Exactly. Yeah, you don't want to hit the pedal. And the first, you know the pedal moved two, three inches because everything in the system is flexing and spreading. You need that precise control to know when the brake's going to lock up and to know that you know the efficiencies there. Every pound of effort you're putting into the brake pedal is actually going into stopping the car.
Speaker 1:Now a lot of enthusiasts at the club level, street level and even up to semi professional will actually be working with a modified street car and upgrading that brake package. Obviously, these days, just about everything that's coming off the showroom floor has an ABS system, and I just want to talk about the considerations here in terms of modifying the brake package but also keeping a balance so that that factory ABS system is still going to be effective. So is there an issue here? Can we just go and throw any brake system on a car with ABS and let the ABS electronics pick up the pieces afterwards, or is there a little bit more to it?
Speaker 2:There's a lot more to it really. You know, an ABS system on a car is calibrated to the size of the brake system that's designed for it. So the piston area, the fluid capacity and even the rotor sizes and pad materials. So most important thing is, when you're changing the calipers is to have a piston area, a total piston area that's similar to the OE size, and also the front to rear ratio has to be the same as well to keep the balance correct. That's the first and foremost, the most important thing if you're going to maintain the stock ABS.
Speaker 1:Now, if you're going to a slightly more race orientated system where you're fitting a pedal box with dual master cylinders and a brake balance bar, again here there's some considerations around the sizing of the master cylinders to suit your calipers, or can all of those pieces being picked up with the brake balance bias?
Speaker 2:The brake bias. The balance bar is really a fine adjustment. First you need to get the basic balance of the system correct with the caliper piston sizing and the rotor diameter sizing, and that's a simple calculation that we can do. Then we'll select the master cylinder sizes, which is sort of the more coarse adjustment for the balance, and then, like I say, the balance bar itself is the fine tuning when you're out on track, just to get that front to rear, just right.
Speaker 1:Are you interested in expanding your automotive knowledge? Start your free lessons with us today at hpecademycom. Forward slash free. Just coming back to the piston sizes and the caliper as well, we see a lot of calipers where, let's say, we've got a four or six piston caliper, the individual pistons are all the same size. And then we've got other calipers where the piston sizes are sort of staggered or differential sizes. Can you talk to us about the reason that we see these staggered piston diameters?
Speaker 2:Yeah, absolutely so. Racing pads and high performance pads have a natural tendency to tape aware for a number of reasons. There's mechanical reasons, where the leading edge of the pad tends to kick in and wear more, characteristic of the material itself. And then there's also some pad migration, where we actually see material moving from one end of the pad to the other. So all of that can add to a very taper-weired pad. So the piston, the staggered pistons, help to counteract that. So typically you'll have a much larger piston on the trailing end of the caliper to tow the pad in, basically at the back end, to keep everything flat, and then you'll get a much longer life out of your pad, better pedal feel and just a better solution all around that makes perfect sense.
Speaker 1:Another thing when we come back to the rotors, we see that in a motorsport application most of the rotors will have some form of slot or groove in them. But not all slots or grooves are created equal and there's a lot of different styles we're seeing on the rotors. Is there a performance advantage to the different styles or why would you choose one over the other?
Speaker 2:Yeah, well, the basic function of the slot is to help get rid of the gases that are generated out of the pad the dust. It helps with the initial bite of the pad. The different designs have evolved over many years. You've got the simple straight groove, which works fine for most track applications. When we get into streetcar-based stuff, the single straight grooves can cause some distortion in the rotor and you might encounter some vibration or noise, that kind of thing. So then that's where we move to a segmented groove, so a lot of smaller grooves around the rotor, so you have a more consistent. You're covering the pad in a more consistent fashion.
Speaker 1:When it comes to fitting a new brake system and going out on the track for the first time, getting the pad and the rotor bedded correctly can be really critical and I think a lot of people really overlook how important that is. And I say, if you get this wrong, you can end up destroying a brand new set of rotors and pads very, very quickly. Can you talk us through what actually occurs during that bedding process and the correct way of doing it?
Speaker 2:So the bedding process does a few things. It brings the temperature of the rotor up gradually so that you don't heat, shock it and cause a possible distortion or cracking. And the other thing it does is it helps to put down a transfer layer onto the rotor, which is essentially pad material being embedded into the surface of the rotor. So you've got a good mating surface for the pad and rotor interface.
Speaker 1:So basically what you're saying there is you don't want to go out with your brand new rotors, get up to 120 mile an hour and brake for the first time as hard as you can. That's sort of going to be the worst thing you could do.
Speaker 2:That's a recipe for disaster. Yeah, that's probably the best way to crack a brake rotor.
Speaker 1:Now, once you've actually done that initial bedding as well, it's important to actually let the rotor and pad assembly cool down. So this can actually take quite a bit of time. You can end up wasting an entire track session just bedding pads. So Alcon actually offer this as a service on a rig. Can you talk us through that? They?
Speaker 2:do? Yeah, so Alcon and our sister company Pro System. We have brake dinos where we have developed the machine and the process to pre-bed rotors off the track so we can deliver you a rotor and pad set that's totally bedded. It's done in a control fashion, so we're not relying on the driver to remember to do it or not, and it saves a lot of time on track. We're at the point where we have different processes for different types of pad, because everything behaves a little bit differently.
Speaker 1:So you're getting that optimum bedding and not wasting a whole bunch of track time potentially beating up on some expensive new components.
Speaker 2:Exactly right. And all potentially damaging them and having to buy another set.
Speaker 1:So while a lot of us at the enthusiast and semi professional level are going to be restricted, budget wise, to a cast iron rotor, particularly in professional levels of motorsport, where budgets really aren't an issue, it's common to see the use of a carbon carbon rotor and pad setup. Can you talk us through the benefits of that system?
Speaker 2:The main thing is weight. A carbon carbon rotor is probably 25% of the weight of a equivalent cast iron rotor. So unsprung weight, rotating weight, it's huge. The downside, or the offset of that, is the cost. They're very, very expensive. They can last a long time but they're very sensitive to the temperature range they're running in. So running a carbon rotor too hot, it'll wear out very quickly, likewise if you're running too cold. So there's a very specific sweet spot and you know there's just a lot of maintenance with a carbon setup.
Speaker 1:In terms of a lot of the high end production cars, we see carbon ceramic rotors. So another take on that can you talk us through what a carbon ceramic rotor is?
Speaker 2:So a carbon ceramic rotor was developed from carbon. Carbon. It basically has added elements that improve the wear of the disc, which makes it much more suitable for the street. It performs very well when it's cold and through the temperature range. But carbon ceramics still have the issues. Where they run very hot, the wear rate accelerates very quickly.
Speaker 1:I mean obviously not a major consideration for a race car with the performance from absolute cold, but definitely much more consideration for your road car. You'd like to know that first time you hit the brakes coming out of your garage, that the car is going to stop Exactly. Yeah, it's been great to get some insight there into what goes into a motorsport brake package. Now, if people want to find out more about the Elkon products specifically, where can they go to? Go to?
Speaker 2:our website alconcouk, or the ProSystem website prosystembrakescom.
Speaker 1:Perfect. Thanks a lot for your time there, Phil. You're welcome. If you enjoyed this podcast, please feel free to leave a review on whatever platform you've chosen to listen to it on. It goes a long way to help us getting the word out there. All these conversations and much more are also available in full on our High Performance Academy YouTube channel, so make sure you subscribe. It's a one stop shop when it comes to going faster, stopping quicker and cornering better.