STI Killer Improvements - Searching For Seconds, Part 1

The STI Killer goes from track junky to an R&D fixture in our quest for lower lap times and improved grip

Justin Cesler Dec 5, 2011 0 Comment(s)
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It has been a little while since we've had the STI Killer in the pages of GMHTP, but it hasn't been for a lack of effort. Since our last official outing, where we bested a Subaru STI around Gainesville's 1.6-mile road course, we have been working almost day and night on the Killer, attempting to take the build to the next level with help from Baer Brakes, Weld Wheels, Toyo Tires, AntiVenom, and ProFab Performance. While the Killer was already a force to be reckoned with, we've set our sights on some much more expensive and capable cars and chasing them down around a road course requires a little more elbow grease and leg work than previously anticipated. This month, we are going to cover some of the work that we've been up to along with some of the road blocks we've experienced along the way.

If you've been following our series, you may remember the six-piston front brakes we re-appropriated from a Cadillac CTS-V. Built by Brembo for Cadillac, the six-piston front calipers and massive rotors (from a C6 Z06) worked really well on the Camaro, although they did come with some compromises. First, brake bias was off slightly and the Camaro didn't bite quite as hard as we had hoped. Secondly, the rear CTS-V brakes that we ordered wouldn't work with our C-clip rear axle, which we hoped we could solve with a set of brackets. In searching for a solution, we found Baer Brakes, a company you are no doubt familiar with, and the company's brand-new Tracker full-floater conversion system for the 10-bolt rear. Built to eliminate the factory C-clips, replace the axles with a double splined unit, reduce axial loads, and replace the factory two-piston floating calipers with massive four- or six-piston fixed units, we knew we just had to get a set for the Killer. Unfortunately, time was not on our side and Baer's production and R&D schedule pushed the Tracker just outside of our deadlines, leaving us searching for a temporary solution, until the Tracker was ready for installation.

It was at this juncture that we chose to prepare the rear end for the Tracker (or an equivalent solution) anyway, by taking it apart, dropping it off at ProFab Performance, and having Matt LaRue narrow the rear to our specifications. If we were going to have to make changes to the rear in the future and cut on it to install the Tracker system, we figured it would be wise to get all of our measurements now, along with our wheel offsets and sizes, so that we wouldn't have to go backwards in the future. Along with that, we also wanted to test fit a set of six-piston Baer rear calipers, along with the company's VeriSlide rear bracket, to see if we could get away without a full floater conversion and to make sure we had proper wheel clearance and braking power going forward.

Enter Gregory Smith and the crew at Weld Racing. Before we could even think about picking a wheel, Weld was on the case, interested in testing and producing a massive set of 18-inch RT-S S71 wheels for the Killer, which could take all the abuse and lateral loads we could throw at them, while keeping us safe on track and holding a set of sticky R-compound tires in true style. In a departure from the Weld wheels that made the company famous, the RT-S line is built upon a modular three-piece design that features a forged billet center and a cold forged rim shell that exceeds SAE J2530 wheel standards and can support loads commonly found only on the racetrack. Above that, Weld Racing offers three different "pad heights," which allow the spoke to clear even the largest of calipers, including the six-piston Baer 6S and 6P calipers we were planning to install. Technical mumbo jumbo aside, the RT-S S71 simply look fantastic and really set the STI Killer apart from other fourth-gen F-bodies we have built thus far, and that alone made them a must have item!

With wheels and brakes in hand, we needed a set of tires that could stand up to the rigors of repeated 20-minute sessions at Sebring International Raceway, take a beating at an autocross, and handle some street and dyno duty on a regular basis. Unlike a drag race application, we were also looking to stuff large 295mm front tires and massive 315s out back, which could keep us glued to the track in any condition. It didn't take long to find Toyo Tires, the company behind the famous R888 line of R-compound tires, which are "Ideal for road racing, track days and high performance driving schools." Perfect. Anyway, enough with the talk, let's see what all of this stuff can do and make sure you stop back to see what else we have in store for the STI--no--Z06 Killer in the future...

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