Series: 2015+ Subaru WRX Modification (Pt.7)
Hello and welcome to my Op-Ed on the 2015+ Subaru WRX! This is part 7 of a 10 part series that plans to encompass all of the information you will need to make informed decisions regarding the best upgrade path for your vehicle.
This week, I will be giving an in-depth overview of Powertrain / Drivetrain Bracing, Suspension, and Braking Upgrades. This overview will consider the purpose of each component as well as what specific brands I recommend.
The statements made in the article below are subjective and based on my knowledge and experience gained from working with the VA WRX platform. Please refer to your preferred tuner, or a trusted vendor, for recommendations on your specific set up.
This Op-Ed is intended to help the user better understand how certain modifications affect the engine and performance, what tuning changes are necessary to account for these modifications, and what brand(s) I recommend for each modification category. This is NOT intended to be a tuning guide. I am NOT an expert in ANY category that will be discussed.
Modifications and Preferred Brands
Powertrain / Drivetrain Bracing
When adding power, it’s always important to understand how the chassis will respond. Most factory support components were designed with specific torque thresholds in mind. When these thresholds are exceeded, the added stress can cause OEM components to fail either abruptly, or over time. Since every build is different, I recommend contacting your preferred tuner when deciding what supporting mods are best for your specific situation.
Some key considerations to make when sourcing aftermarket bracing are as follows. What are the power goals? The more power you make, the more reinforcement will be required. How will the car be driven? Daily drivers will not require the same supporting modifications as race cars will. Extra bracing will typically make the car more noisy and less comfortable, especially on long trips. To better understand what components are best for you, contact your preferred tuner or even a trusted vendor.
For chassis bracing, I’d recommend the following upgrades depending on your situation: Perrin Pitch Stop Mount and Pitch Stop Brace Kit. These two modifications can help redistribute the bending moment between the engine and the transmission to other parts of the vehicle’s frame. This can help prevent components from being damaged due to elevated levels of torque stress. The Pitch Stop Brace Kit also comes with a stainless steel clutch line that can help increase positivity in both clutch feel and engagement.
Suspension is what will keep your tires in contact with the road. As a very complex subject, suspension setup will completely rely on your vehicle’s intended use, your preferences, your driving style, and many other factors. A good suspension setup is well thought out and proven under certain conditions. As with most things, functionality is fundamental and looks should come second. Your safety and your vehicle's cornering performance should ALWAYS be a top priority when upgrading or changing suspension components.
Some key considerations to make when sourcing suspension are as follows. How will the car be driven? Daily drivers and race cars will require vastly different setups. Depending on your intentions, different combinations of spring rates, ride heights, and dampening may be necessary. Do I require on the fly adjustability? If so, air suspension may be your best bet. Air ride cannot match the functionality of a well dialed-in coilover setup. However, for certain applications, the versatility of air ride is simply unmatched. Can I simply get lowering springs and call it a day? Many people have seen success with a lowering spring setup. However, I would advise against it. OEM struts were designed to work optimally with OEM springs. When you change those springs out, you not only put the OEM struts outside of their intended dampening zone, but you also put transfer stress and impulses through the struts during operation. This will typically lead to poor suspension performance and premature failure of the struts. Nevertheless, if you pair a lowering spring with an aftermarket strut that was designed to dampen optimally with said spring, this could potentially be a more cost effective solution for you, depending on the application.
For a coilover setup, I’d recommend something from Fortune Auto. They have been in the business for a very long time and only release a new product once it has been extensively simulated and road tested. They are also the pinnacle of price for performance and are widely known for being one of the best “bang for your buck” options out there. For air suspension, my knowledge is fairly limited. In either case, It is best to contact a suspension or fitment specialist regarding what setup is best for your situation.
After adding all that power, you’ll need some extra help slowing down. The factory brakes are sufficient for daily driving. However, under heavy or extended use, there are a few major concerns. The brake pads will fade, the rotors will warp, the lines will expand, and the fluid will boil. All of these things can lead to a substantial decrease in braking performance and a potentially dangerous situation.
The only key consideration to make when sourcing braking components is as follows. How will the car be driven? Daily drivers and race cars will require vastly different setups. Depending on your intentions, different combinations of pads, rotors, lines, and fluid may be necessary. The level of heat capacity and wear characteristics will also come into play when determining what upgrades are best for your specific situation. Braking setups vary across different racing disciplines from Autocross to Time Attack and everything in between. In most cases, it is best to consult with someone who has on-track experience before making any expensive brake purchases.
Do not be fooled by fancy designs in brake rotors. Drilled or slotted rotors may look nice. However, they may not be the best option in some cases. While slotted rotors can aid in the disbursement of brake dust, drilled rotors offer few inherent benefits over well designed blank rotors. At the same time, most track day enthusiasts often opt for blank rotors as they are the cheapest to replace when the time comes. Take all of these factors into consideration and contact a trusted vendor to identify what rotor setup is best for your specific situation.
As far as brake pads go, there are plenty of considerations to make. Different brake pads will produce different amounts of stopping power, different noise and dust levels, and different longevity characteristics. Too aggressive of a pad on a street car will create excess dust and noise. Too docile of a pad on a track car will result in brake fade or accelerated wear. At the same time, pads should be sourced with rotors in mind. Too aggressive of a pad on a street rotor can lead to the rotors warping or delaminating. This directly effects not only the performance of your braking system, but the longevity of the components as well.
Regarding brake lines and fluid, traditional rubber lines will expand as pressure and heat build in the braking system. This can result is negative pedal feel and a decrease in maximum braking pressure. At the same time, boiling brake fluid reduces the fluid’s ability to remain incompressible and extract additional heat. For these reasons, selecting a fluid that can resist boiling and lines that can resist volumetric expansion are critical in maximizing your braking performance. This is especially important when it comes to high stress situations, such as track time and autocross.
For braking setups, I’d recommend Hawk Pads, DBA Rotors, StopTech Lines, and ATE-200 Fluid, or perhaps a Big Brake Kit from your preferred manufacturer. Since brakes function by transforming kinetic energy into heat via friction, heat extraction should may also need to be considered. This can be addressed via brake ducting or other methods of increasing the flow of clean air over the braking surface(s). In any case, It is best to contact a braking specialist, or a trusted vendor, regarding what setup is best for your specific application.
Tune in next week (03-22-2021 @ 12:00 EST) where I will be giving an in-depth overview of Transmission and Clutch Upgrades. This overview will consider the purpose of each component as well as what specific brands I recommend.