posted on December 04, 2013 10:31
Project Autocross BRZ: Part 1 - Building a Better Cone Dodger
Let’s face it, autocross is hugely popular. There is a statistic floating around that the SCCA Solo II Nationals is the largest motorsport event in North America. While I have not audited that fact, I can tell you that a LOT of people love the sport. In fact, my very first interest in automotive performance was an autocross event that I attended and competed in after being encouraged by a friend to give it a try. After that event out came the stereo and in went suspension modifications. That car was Project 200SX and the year was 1999. I have always had a penchant for the sport but after spending more time at the road course, life sideswiped me and my participation in AutoX events waned; that is, until recently.
After the Subaru BRZ and Scion FR-S were introduced, they became immediately popular on the autocross circuit and for good reason. With their balance, braking, and neutral handling, the theory was that they would be very competitive in several different autocross classes. It was time to bring autocross to MotoIQ and it was time to build a BRZ for SCCA Solo II competition. Our car is a 2013 Subaru BRZ premium in World Rally Blue and honestly, it is the first time I felt like I LIKED the WRB color! With the car chosen, we had to decide on what class to run and immediately begin to prepare the car to the maximum extent of the ruleset. With the car being a joint effort between myself and its owner, Bart Hockerman, there was no time to rest and start racing the car in stock form. Bart is a serious competitor within the sport and in order for the car to be competitive at local and national level events changes needed to be made and FAST! While we will move quickly with putting parts on the car, this series will also cover more subtle changes in setup as we do more events with the car and learn to better exploit the car's potential.
The car looked like this for less than 2 weeks! If you want to be competitive when autocrossing on a local (let alone a national) level, a stock car won't cut it. Besides, I never cared for the OEM wheels or overall stance. Oh and thankfully our car does not have the OEM rear spoiler!
The FIRST step was to closely review the ruleset for our chosen Street Touring Extreme (herein after referred to as STX) class. In a nutshell, this is a class designed to showcase a vehicle's mildly modified performance. Tires are limited to DOT rated legitimate Street tires with a minimum tread wear rating of 140 UTQG, wheels are able to be changed, suspension is fairly open but limited to using the factory mounting points, and there are some regulations regarding damper amount of adjustability. Power adders are limited to bolt on’s, catalytic converters must be retained and cannot be relocated more than 6” from the rear-most OEM cat placement. A bolt on street car is essentially what this class is designed around. For this reason, it is very appealing to many people as it makes for close competition, as well as being easier on the pocketbook than some of the more extreme classes. Make no mistake, serious thought and effort is put in to sorting out the best of the best within this class. However, the cost of entry is much less than many other classes and the amount of fun to be had is EPIC. If you are super curious as to the ruleset specifics you can find them here.
Before we even took delivery of the car we had reached out to our good friends at Kartboy. Having used their parts with great success on our Gen 3 STi project, we knew we would want to see what they had to offer for the BRZ. They were the some of the first people to release a short shifter and they did a fantastic job with this part. The OEM shifter is nicely placed and not horrible by any stretch; however reduced throws, a shorter shifter position, and a tighter feel is always welcomed (did I just say that?). The Kartboy shifter is a complete replacement piece that reduces throws by 28.5% and is made right here in the USA, each one hand welded on the same jig. The kit also includes the proper parts for the reverse lockout mechanism. What we liked most about the shifter swap is that it can be performed completely from the inside of the car! No need to jack up the car and remove the exhaust or other baloney. Just sit inside enjoying your milk and cookies and watch Bart install the thing... err... I mean the install is very straightforward.
The Kartboy SS in all of it's installed glory. Bart installed this thing so quickly I only had time to consume 2 beers (um, milks). Also notice the necessary reverse lockout bracket that is included with the kit.
The shifter and transmission bushings from Kartboy also serve to tighten up shifter feel and afterwords everything was very crisp and direct. We maintain that by reducing the shifter throw we will have a competitive advantage over other cars in our class who take longer to shift... OK that is total nonsense but I am sure you could overhear that type of banter in the grid at an autocross event- they really are that serious about their car prep.
The Kartboy Transmission Bushing fills the void in the center with 85A Durometer urethane. It's like Viagra for your tranny... Wait... err...