When it comes to modifying cars, most people will generally increase power, then improve handling, then improve braking. The idea of bigger is better does not apply to many things in the automotive industry, but in the case of brakes, it absolutely does. At a certain point, upgrading pads and fluids is not enough, and you need to replace the entire system with something larger and more performance oriented. The idea of a big brake kit is to improve braking performance in every way possible by using a larger rotor, caliper, and pads compared to the stock system. There is a lot of misconception about how a big brake kit improves performance, and at what point you should consider purchasing one, so in this short article we will clear some of that up.
Dealing with Heat
As you probably know, most automotive braking systems (aside from vehicles with regenerative brakes) use the friction of pads squeezed onto a rotor to slow the vehicle down. While this design works just fine, it effectively turns all that rotational energy into heat, and heat has a tendency to break things. Most OEM brake systems are designed to deal with the heat from braking on the street and maybe a tiny bit of track usage, but they can quickly heat up to the point of becoming ineffective.
The heat is spread across the pad and the rotor, which means size changes how the system absorbs the heat. A larger rotor can absorb more heat than a smaller rotor, and the same goes for pads. The reason race cars use massive rotors is to deal with the insane amounts of heat more consistently braking very hard. If your brakes become too hot, you will experience brake fade, and eventually, that heat will boil the brake fluid which will render your brakes completely useless, possibly resulting in a very bad situation.
Big brake kits use larger rotors, calipers, and pads compared to the OEM brakes, which mean the entire system can deal with much greater amounts of heat compared to the OEM brakes. This means you can brake very hard, repeatedly, without running into brake fade. This is incredibly important for track use, heavy towing, and even hard street driving.
More Pad Doesn’t Mean More Bite
The big misconception is that larger brake pads and rotors equal more stopping force because the surface area of pad to rotor contact is larger, but this is untrue. Coefficient of friction has nothing to do with surface area, in fact, the surface area is not even part of the coefficient of friction formula! A larger brake pad will only spread out the clamping force of the brake caliper over a greater area. The brake pad will always retain the same amount of friction between pad and rotor regardless of any increase in brake pad surface area.
With the larger pads and rotors, you can run more aggressive pads which have a high coefficient of friction, without running into heat issues, plus the larger size means the pad will last longer overall. To put it simply, a larger pad doesn’t mean more bite, but a larger pad can be more aggressive without running into the same amount of heat and wear issues compared to a smaller pad. So, a big brake kit does not guarantee more brake force if the pads have the same coefficient of friction compared to the stock pads. Luckily, most big brake kits have relatively aggressive pads so that you will see an increase in braking performance from most big brake kits.
When Should You Upgrade?
This all leads up to the question, at what point should you upgrade to a big brake kit. There is not a definitive answer to this question, as every vehicle and owner is different, but there are some situations where a big brake kit could be considered necessary. If you plan on going to the track, chances are your stock brakes will not be able to keep up with the demand, so a big brake kit is definitely a good idea. For AutoX racing, the racing is pretty short, so a big brake kit is not absolutely necessary, but is a good idea.
If you are towing a lot, a big brake kit can be a good idea, as the adding weight will force your brake to work harder, even with the trailer brakes set up properly. For street use, OEM brakes are fine as long as you haven’t massively increased power. Once you increase power, you will also be increasing the speeds, meaning your brakes need to work harder. Depending on how hard you drive, a big brake kit may be needed even on the streets.
To summarize all this, just remember that big brakes improve braking performance by increasing the amount of heat the braking system can absorb without failure. Many big brakes kit will use multipiece rotors which are lighter than the stock rotors, resulting in less unsprung weight which will improve initial turn in and steering response. Some of our most popular big brakes come from Brembo, WP Pro, KSport, Rolloface, and Baer Sport.