The Subaru BRZ was the car of choice in 2014 when DirtFish added a rear-wheel-drive program to its roster. This choice expanded what we have to offer for our students, and also allowed for a more economical experience than the WRX STI while still providing the thrill of rallying.
While our fleet of BRZ school cars aren’t fully built like our Open 2WD class BRZ which is currently being driven on the stages by lead instructor Nate Tennis, there’s still a lot of prep that goes into each vehicle to ensure they’re rally ready, and able to reliably provide the full DirtFish experience.
Drivetrain
It doesn’t take much to get a small, lightweight chassis such as the BRZ sideways in the dirt. Our fleet utilizes a mostly stock drivetrain, retaining the original 200 horsepower setup from factory.
The FA20 flat four helps keep the vehicle’s center of gravity low allowing for better handling, and is able to last about as long as a built engine in our harsh conditions and high intensity driving.
The six-speed manual TL70 transmission also stands up to the abuse of all day gear slamming quite well, and an automatic car that can be set up for hand controls utilizes the stock automatic six-speed from the BRZ.
The ECU has also been tuned for more performance oriented engine response and to clear out any OEM hindrances that would hold the car back.
The most important change in the drivetrain is arguably how it connects to the car, as the factory mounts are susceptible to failure in the extreme conditions rallying can throw up.
The OEM engine mounts for the BRZ are made of a plastic material with a rubber bushing, and can snap easily after repeated high speed driving on rough roads. The plastic is replaced with steel, and the bushing is also replaced in the process.
Similarly, the subframe mounts and differential mounts are upgraded to allow for far less play. Without these, it’s even possible for the diff to shake itself out of the car!
The power connects to the rear wheels from there with a set of Driveshaft Shop axle shafts rated at 1000 horsepower to make sure they can handle the shock load of anything that might happen on course.
Interior
Interior modifications to the BRZ serve two main purposes: safety, and weight reduction.
Looking at the interior it’s clear there’s not much resemblance to the OEM vehicle, save for some of the remaining plastics.
Infotainment systems have been stripped to save weight and parts like seats, steering wheels, and safety belts have all been removed and replaced with their race-spec equivalents.
A communications system has been added to allow student and instructor to talk to each other over the sounds of the car.
Most importantly, a full, welded in roll cage has been built into every vehicle to protect the occupants in the unlikely occurrence of a hard wreck.
Brakes, wheels and suspension
No matter how much work is put into the interior and drivetrain, it would all be useless without anything to connect it all to the ground. For that we have 15-inch Method Race Wheels wrapped in Hoosier gravel rally tires.
The smaller-than-OEM wheels rub on the front tie-rod if installed on a factory set up, so the steering location has been moved further in on the knuckle which not only allows for the tie-rods to be safely cleared, but also for quicker steering. There’s now roughly two full turns of the wheel from lock to lock as opposed to three.
The suspension up front is a Reiger racing set-up with fixed dampers, while the rear has a universal Bilstein motorsports shock that is modified slightly to fit the BRZ. This set-up helps not only improve handling, but also can be rebuilt in the case of failure, while am OEM set up would need to be fully replaced.
The cars are able to maintain their OEM suspension arms, as well as other components with this set up, while still not compromising on performance.
The brakes are set up to be more race-spec as well. They’re fully manual without any power assist, and have upgraded brake lines and other such components to ensure safety.
Of course, the cars are also equipped with a hydraulic handbrake to assist in pitching the car sideways. The handbrake can also act as an ‘instructor brake’ if need be.
Bodywork
To protect the exterior of the car from the constant barrage of gravel it experiences on a daily basis, a lot of protection has been put in place.
To start with, the entire underside of the car has been covered with high-density polyethylene plastic (HDPE) to help prevent mud, dirt, and gravel from packing itself into all of the small areas under the car. This also protects the underbody if the car were to go over something capable of causing damage.
Standard wheel wells aren’t sturdy enough in the long term for the life of a DirtFish car, so they’ve been replaced with custom ultra-high-molecular-weight polyethylene protective arches.
Just outside of the wheel wells, a custom polyurethane mudflap set helps keep the roost to a minimum, and specifically away from the body where it can cause large amounts of damage.
The BRZ fleet also has carbon Kevlar body protection to help protect the areas of the car most susceptible to damage.
Everything adds up to a well-built car capable of reliably reaching the basics of RWD car control and rallying to people of all skill levels. It remains a great choice for people who want to focus on throttle control and perfecting vehicle input where traction may be lacking.
