With any fast car, stopping power is essential. For the high performance Z cars, this axiom is doubly true, and any owner of a Z that plans to track their car knows to keep their brakes in peak condition. This is often done at a Nissan dealership, who specialize in Nissan Brake Service. For harder track use beyond light trackday sessions or autocross runs, it is recommended to upgrade your brakes.
As a sports car, a 350Z or 370Z’s braking system is optimized from the factory for spirited street use. This essentially means having fun and using the sports cars as they were intended. The factory Z car hardware can handle more than this for short periods at a time, but if a driver intends to go above and beyond and competitively track their Z, the brakes should be upgraded to maintain the same margin of safety.
The reason a track-deployed Z needs upgraded brakes is, in a word, heat. Disc brakes work by converting rotational kinetic energy into heat. A factory braking system is only designed to handle so much heat at a time before it begins to lose effectiveness, while an upgraded system can handle much more.
On the street, one never stops from high speed more than once in succession. During a 20 minute trackday session, depending on the track in question, the car will decelerate from very high speed a dozen times or more. That is roughly the practical limit to factory brakes, which will need a significant cool down period after each session.
Upgraded brakes are a small and worthwhile investment if one intends to do more intense driving than introductory trackdays, and in many cases even as a general upgrade before one hits the track at all.
Brake System Overview
The disc brakes used on all modern passenger cars are paragons of simplicity, effectiveness, and reliability. Overall, five parts are used to convert huge amounts of rotational kinetic energy into heat, and they can do so in practically any weather condition and in most cases will work without issue for decades on end.
Those five parts under each corner of the car are the rotors, calipers, pads, lines, and the fluid in said lines. The rotors are used to dissipate the heat generated when braking, and spin with the wheels. The calipers are stationary, and positioned over the rotors and hold the pistons which push the pads into the rotors to perform braking. The pads are where the rubber meets the road in braking, or more literally, where the pad material meets the rotor. When the brake pedal is pressed, the pads are shoved into the rotor by the pistons in the caliper, pinching the rapidly spinning part and forcing it to slow down. The brake lines are how brake fluid travels into the caliper, and allow the whole system to actuate on command.
The rotors, pads, and fluid are the most important parts of that system, and all of them are susceptible to the amount of heat generated by heavy track use. That is where upgrades come in.
Rotors
For drivers who only track their car for fun, and not in competition, the factory rotors should actually hold up well. But the moment one goes from trackday sessions to any kind of classed racing or competition, the rotors should be upgraded. Larger rotors have more surface area to spread out heat, while slotted and/or drilled rotors include more locations designed to let heat escape. When properly designed, a slotted or drilled rotor maintains strength while using whatever surface area it has more efficiently than a blank rotor. Rotor material and construction also matter, and some brake kits even allow the system to tolerate far more heat while both improving braking force and reducing weight.
Unsprung weight, that is, weight not carried by the suspension, actually has an outside effect on performance. The rotor, wheel, and tire are all prime examples of unsprung weight, and the heavier they are the harder it is to accelerate, brake, and turn. High performance rotors not only improve the heat tolerance and stopping power of a braking system by being more capable, but by being lighter.
Calipers
Generally speaking, if not opting for a total big brake kit, calipers are the last part requiring individual upgrading. They perform a vital function, in pressing the pads to the rotors. But to stop a vehicle of a Z car’s size and weight, the factory units can generally do the task even in a low level competition scenario. This is largely because stopping repeatedly from high speed is more about heat resistance than actual braking force. The need to upgrade calipers, in order to apply more force to the pads, only arises if the vehicle gains significant weight or is stopping from extreme speeds.
“Extreme,” in this case, means something like professional-level wheel to wheel GT4 racing, or above street class time attack racing. Stopping from 120 miles per hour is very different from stopping from 150 miles per hour. Upgraded calipers can also make the brake force applied to the pads through the pistons more even across the pad surface.
Pads
Brake pads are the most important individual part in a braking system for most light track and autocross drivers. On a modern sports car, the fluid is the only other common "weak" point when pursuing that required margin of error in braking capability on track. Upgraded pads tend to make more noise than factory units, but will handle significantly more heat than their more docile siblings.
The best modern brake pads maintain near-factory levels of refinement on the street while at the same time offering enough heat resistance on track to keep the brakes performing at their peak in a trackday setting. That said, when moving from trackdays to competition, generally comfort needs to be sacrificed for performance.
Lines and Fluid
Often overlooked, the brake lines and the fluid that runs through them are what actually actuate the brakes when the brake pedal is pressed. On older vehicles, replacing the brake lines is a common and understandable upgrade as the rubber lines get brittle past 25 years of age. However, on a modern Z car like a 350Z or 370Z, the stock brake lines are not only still fresh, but are made of slightly sterner stuff than what came on cars two or three decades ago.
What should be changed and bled before even a trackday is the braking fluid. The most heat sensitive part of just about any braking system, braking fluid meant for the street from the factory rarely holds up under the pressures of track use, leading to spongy pedal feel and eventually some loss of overall braking performance. A high performance brake fluid will solve that problem with very little effort.
Conclusion
Brakes may be simple, but they are critically important, especially on a vehicle intended to hurtle down a back straight with a hairpin at the end. Modern Z cars come with capable brake systems, but when one intends to hit the track, those systems require minor adjustments and updates to provide the safe and secure experience a Z driver is looking for when howling past their competition.
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