Road and Track Magazine recently published a brief article touching on how we prepped our class-winning Dark Helmet Plaid Model S race car for Pikes Peak.
One of the most important topics of taking a Plaid on track is braking. As such we’ve created this more in-depth guide to expand on the topic given how important it is and how much testing and R&D we’ve completed since beginning with Dark Helmet’s development earlier this summer. We will continue to edit and update this guide as appropriate.
Let’s begin.
There is no doubt that the Tesla Model S Plaid is a new category of car. The performance defies physics as the 4800lb family sedan routinely outperforms Hypercars at multi-million dollar price points. This also introduces new challenges never before encountered because there is truly no other car that has ever weighed this much that manages to find itself driven by owners in high-speed racing environments with such demands to consistently decelerate from triple-digit speeds. The average track day car or race car often weighs nearly half as much and yet accelerates nowhere near as quickly as this new breed of Tesla. So let’s address the issue of reliably stopping a heavy-duty missile and the challenges at play.
Let’s get this fallacy out of the way, nothing is indestructible. Upgrades to brakes can surely increase the upper-performance limits but there is no brake upgrade that cannot be destroyed if subjected to extreme enough abuse. This reality applies to all vehicles and Plaid is not unique. It is possible to overheat and permanently damage the brakes of any car, it just so happens that with a 4800lb car it is that much easier to end up in the danger zone. The objective of this guide is to provide guidance towards increasing the car’s braking performance capabilities and also to provide some perspective in the hope for further informed safer driving on the race track.
Thermal Capacity Overview
Anyone who has driven the Plaid knows that the brakes in a street environment are capable of emergency stopping and a wide range of use cases. The challenges found on a race track are unique in that they involve higher speeds, more frequent braking, and less recovery time for heat to dissipate. Doing a high-speed stop one time is no problem for most brake systems, but doing that same high-speed stop multiple times is an entirely different challenge. Thermal management is the name of the game when it comes to increasing the usability window for racing environments.
Thermal Capacity Increase With Brake Ducts
A universal win and what we consider to be a prerequisite to tracking the Model S is our brake duct kit (further product photos and information to debut soon). As an example, we took the same car with an upgraded brake kit and we heated the brakes with extreme and repeated high speed stops until the brakes reached nearly 1000 degrees Fahrenheit at the rotor. In this test, we blocked off our brake duct inlet on one side and allowed our brake duct to flow air on the other side. The blocked-off side is blocked off in the same way all cars come from the factory. The result was 971F on the side without brake ducts and 701F on the side with brake ducts.
Simply said brake ducts can massively increase the usable braking performance before temperature-related falloff is reached. This is why you’ll see brake ducts on our project Dark Helmet during Pikes Peak and our record laps at Laguna Seca. Brake ducting is compatible with any brake upgrade and it can mean the difference between brake reliability and brake failure by the benefits to heat management they provide.
Thermal Capacity Increase with Rotor Thermal Mass
Just as in any car, the front brakes are always the largest and contribute a bulk of the braking duty. They also are frequently the most susceptible to overheating which results in brake fade and general unreliability as temperatures increase. It is for this reason that our brake duct kit is for the front brakes and it is also for this reason that all of the front brake rotor options are thicker and have a larger annulus than the factory rotor. The more rotor mass in both thickness and in annulus there is, the better the thermal management there is and the higher limits of heat they can absorb. In the case of our UP x PFC rotors which utilize the factory calipers we’ve maxed out the caliper’s maximum permissible width by increasing the rotor thickness to 34mm and by pairing our brake pads that allow that thickness to be possible. Additionally, we’ve added a wider annulus to the rotor without increasing the actual rotor size and we’ve paired that with a larger brake pad to utilize the wider annulus.
This enables the thermal capability and stopping power of a larger rotor but in the same rotor footprint size which as a result ensures lower rotating mass for faster driving response and also allows all 19” and up wheels to fit which is critical for sourcing tires to race on. In the case of our carbon ceramic superlight kit we’ve also packaged that kit to fit 19” wheels for racing, but in that kit, we gain further benefits of a new caliper which allows an even taller and wider carbon ceramic rotor. We’ve managed to increase pad to rotor surface area from 77.5cm² (standard equipment) to 149.4cm² with this kit. This represents a massive increase of 93% while still fitting factory 19″ wheels.In all cases, thermal limits are increased which means the car can race longer with more reliability.
Brake Pads
As we’ve discussed with thermal capacity above, racing a car results in very hot brakes. During spirited driving with routine and hard stopping the brake system will exceed usual limits found in daily driving environments. Factory brake pads can be excellent for expected uses but for racing or very aggressive driving, a specialized brake pad is needed to increase the operating temperature limits designed into the pad. We offer a range of brake pads in two different compounds. Our Street Sports compound is designed for daily use and has a high-temperature limit combined with low noise and low dusting which can be fitted to factory brake rotors, to our UP x PFC rotors, or to our Tesla Model S Plaid carbon ceramic kit.
Street focused brake pads are great for a daily driven car but are not advised for more serious track work. For racing, we have our Racing and Competition brake pad compound. The nature of these pads is that they have a much higher operating temperature range to ensure reliable stopping and great brake pedal modulation working well into stratospheric temperature ranges. The race pads do exhibit more dusting, work better at higher temperatures and can at times exhibit some noise under braking although the beauty of driving a Tesla is that brake engagement during normal commuting is quite minimal due to regen. As stated earlier, no product is indestructible and driver strategy always plays a role to monitor and manage the car during extreme use. The objective of our brake pads is to provide appropriately raised temperature ranges for use cases. For track use, we would always advise pairing with our brake ducts at a minimum to help control temperatures.
Brake Fluid & High Performance Driving – Avoiding Loss of Pedal
Brake fluid plays a vital role in the performance and reliability of every brake system, especially so in high performance driving. A professional brake bleed with high performance fluid is a requirement for the functionality of our brake system (and any brake system). We recommend using Motul RBF 660 (our go-to fluid) or Endless RF-650 brake fluid. Brake fluid should be flushed frequently for race cars in particular because over time moisture content builds and moisture inherently decreases the temperature limit of the brake fluid. Brake fluid and the temperature capabilities of it matter especially due to the high temperatures the heavy and powerful Model S generate. The higher temperatures seen in the brake system transfers heat to the brake fluid and when brake fluid boils those bubbles create air in the brake lines. Air in the brake lines from boiled fluid can create near instant loss of brake pedal. Therefore, using a high temp brake fluid and managing brake heat is a key to safe braking for extreme environments. Loss of pedal is a different symptom than brake fade and typically a symptom of brake fluids exceeding their temperature range (or alternatively a leak in the system) whereas brake fade is often a byproduct of the brake pads exceeding operating temperature range. In both cases managing temperatures in a racing environment and adequate testing is typically found in motorsports drivers and always strongly encouraged to get the best and most safe result. We flush our brake fluid after each race and we monitor caliper temperatures for these same reasons on our race cars. Please always feel welcome to talk to our team if you have questions about motorsport use. For street driving the temperatures seen are significantly less and this plays a lesser role although the same fluids are suggested for street cars as well.
We can also suggest pairing a brake fluid changeover with our stainless steel high-performance brake lines for a consistent and confident pedal feel.
Brake Lines
Our stainless steel brake lines provide a significant change in pedal feel and consistency. While traditional factory brake lines are rubber and can expand under heavy loads, our brake lines provide a consistent and confident feel even in extreme environments. They provide durability and consistency for street use or for racing environments and are a no downside product that are best suited to be fitted at the same time as a brake fluid flush.
Wheel Sizing
We have had a focus on engineering all of our brakes to support 19” wheels (and of course anything larger will fit as well). This has been a priority for us in that we find that the bulk of high-performance tire and racing slick options max out in 19”. We had to get creative in our design and packaging to fit the bigger brake pads, wider rotor annulus and increased thickness of our systems into a footprint that accepts 19” wheels. This struggle we believe is worth it because of tire options for our clients who love to drive.
The Upcoming Tesla Factory 21″ Model S Plaid Specific Brake Kit
Tesla Model S Plaid Carbon Ceramic Brake Kit
We love that Tesla is going to offer a track orientated brake kit! This kit is listed for future sale by Tesla to be exclusively offered to Model S Plaid variants with 21″ wheels with a targeted mid 2022 release. There is no doubt that their brake kit will be up for the task of racing use. Even more-so, when paired with proper ducting. From our side, we will be supporting clients of this future Tesla release by making a version of our brake duct kit that will accommodate the Tesla track brake kit and we will also be offering high-performance replacement brake pad variations for their brake kit.
Factory Front Dust Shields
On our race cars, we remove the dust shields. We’ve tested with and without and the dust shield does trap heat and lead to faster heat ramp and retention of all rotor variants. For a street car, the dust shields are fine to keep (depending on the kit they may need trimming) and for a race car, they’re also fine to keep as well although plan for higher temperatures. The best outcome is to utilize our brake duct kit which resolves this issue. We do advise in any case to use foil tape to heat shield critical components when racing.
Monitoring Temps When Racing
A safe rule of thumb is to immediately do a cool-down lap whenever the car identifies a brake overheating situation. While adding upgraded braking capacity can increase the thermal limits beyond the car’s knowledge, it is always better to be safe than sorry. Driving without heavy braking will allow time for the brake system to shed heat and for airflow to help cool the brakes down into a safer operating temperature. Additionally, for racers, we do advise applying heat-sensitive paint to monitor frequently the temperature peak ranges you’re seeing. This will help advise on safety as well as strategy. IR heat guns are also readily available online and can be a useful tool to measure brake temperatures after a run, here’s an example of an inexpensive (sub $60) Infrared-Thermometer.
Cool Down After Spirited Driving
Always cool down the brakes after hard usage. The brakes can see extreme temperatures and it is vital for prolonging the life of the components to bring them down to a reasonable temperature before stopping. This is also extremely important for electronic parking brake applications which should not be applied to a very hot rear brake. You can resolve this by driving around easy on the brakes for a cool-down lap.
Which Brake Kit Is Best for Me?
Choosing brake upgrades is a very personalized process. We do not believe in a one-size-fits-all approach since everyone has different goals, drives differently, has different budgets and needs. As a result, we have been developing a very comprehensive and wide-ranging series of options. Please reach out to us at info@unpluggedperformance.com for a consultation so we can discuss your goals. The initial things to consider are always going to be:
- Budget: This may rule out options for carbon-ceramic rotors.
- Racing Use or Street Driving Only: If racing this will rule out street pad options and should require upgraded fluid, race pads, a thicker rotor option, and brake ducting at a minimum.
- Wheel Sizes For Clearance: You’ll want to ensure your brakes fit whatever is the smallest set of wheels you might be using (winter wheels, racing wheels, etc).
