Project 3G Vette Part 3 - PHR Project Car

The Art Morrison Enterprises 3G Vette is an exercise in multitasking. Its mission includes accelerating in a straight line with a minimum force of 1 g, turning around corners with a minimum lateral force of 1 g, and decelerating with a minimum requirement of 1 g. Those are the three "g's" of the 3G Vette. In Part 1 (Nov. '07), we introduced you to the Morrison GT Sport Chassis for first generation Corvettes, covering its design and fabrication. Part 2 (Dec. '07) was our walk-around of the powertrain, which included a potent all-aluminum 427ci small-block from World Products (550 hp) and a T-56 six-speed gearbox from Rockland Standard. This month, Craig and Art Morrison show you how they created a truly world-class braking system from available shelf components. The icing on the cake is a custom air duct system for cooling the brakes. Yes, this is a vehicle destined for hardcore abuse on the race track. Here's how it went down, as told by AME's Craig Morrison.-Johnny Hunkins

After much thought, planning, and execution, we are well on our way to finishing the 3G Vette. There is one last "g" that remains: deceleration. So, the obvious starting point for the last of the 3 g's is the brakes. Despite having C5 suspension on the front of our 3G Vette project, and therefore phenomenal OE brakes, the aftermarket options are even better. That's how our quest for more braking performance started.

Up front, we are using the latest offerings from Wilwood. The SL6 kit is a 14-inch rotor with a six-piston caliper, and is a direct bolt-on for the C5 spindle. The SL6 caliper is a fully CNC-machined billet unit with closed ends and a reinforced bridge. Not only does this provide extra strength in the caliper, but it is highly resistant to separation and deflection under hard braking. Relying on its race experience, the SL6 caliper also features a staggered piston configuration to generate a high clamping force that is balanced over the entire brake pad area. An extra benefit of this staggered piston setup is that the pistons compensate for the normal variances in temperature, load, and wear, extending the performance of the brake pad.

The massive 14-inch rotors used in the SL6 kit are made out of premium, "long grain" carbon iron, which helps to provide a long-wearing rotor that has less distortion under high-heat situations. We chose the SRP rotor that offers the directional cross-drilled and face-slot pattern. In addition to their visual appeal, the venting and cleaning action of the holes and slots reduce pad glazing. This minimizes irregular pad wear and helps to regulate surface heat. The SRP rotor is also zinc-washed to reduce corrosion on all areas of the rotor that are not kept clean by the brake pads. Simply put, the Wilwood SL6 kit has enough bite to knock granny's dentures out with one tap of the pedal-and then some.

For the rear brakes, we used the Wilwood Superlite 4R brake kit. Featuring an internal-drum parking brake that is integrated into the bolt-on iron disc hat, it offers all the clamping force you need in an uncluttered package. Designed to work with stock or aftermarket cables, we easily routed the emergency brake lines along the chassis and connected them to the OE parking brake handle.

At the heart of this kit is the substantial forged 4R caliper. The same size as the SL6 caliper, this FEA-designed forged billet body provides a highly efficient clamping force while producing the least amount of deflection of any caliper in its class. A radial mount securely attaches the 4R caliper to the rear axle, providing two separate planes of adjustment. This enables you to precisely locate the caliper and brake pads over the rotors. Thanks to the top-load design, the pads can be easily inspected, serviced, or replaced without having to alter the initial setup.

Straddled by the calipers are the SRP 13-inch diameter rotors. Just like the front rotors, these pieces are directionally drilled and slotted to maximize pad performance, and zinc-washed to prevent corrosion. Because the gasses produced in hard braking are vented while dust and burnt material are constantly being cleaned, the pad performance is enhanced and braking feel is consistent for the life of the rotors and the pads.

Included in this formidable braking package is a set of the Wilwood BP-10 Smart Pads. These pads use a metallic-composite compound that offers the improved friction and high-fade resistance of an entry-level track pad, while delivering the low-noise and dust-free performance that you would expect in a street pad.

Providing the hydraulic pressure for this system is one of Wilwood's pedal assembly and master cylinder kits. Specifically, it's Wilwood's "reverse swing-mount triple master cylinder clutch and brake pedal with balance bar." [Try saying that three times real fast.-ed.] With everything in one unit, we have the clutch and brake pedals with a master cylinder for the hydraulic throw-out bearing, as well as two master cylinders for the brakes. Using two master cylinders for the brakes allows us to eliminate the compromise of trying to have one bore size work for both the front and the rear. A balance bar between the two lets us adjust the bias for maximum braking performance. For this particular application, we are using a 13/16-inch bore master cylinder for the front brakes, and a 7/8-inch bore master cylinder for the rear. By using a smaller front bore, we are increasing the amount of pressure going to the front calipers, which increases the clamping force on the rotors.

In conjunction with the Wilwood dual master-cylinder kit, we used a remote brake bias adjuster. Because of the location of the master cylinders, this adjuster enables cable-actuated adjustment of the balance bar between the master cylinders. The bias adjuster allows us to fine-tune the balance of front-to-rear braking force, maximizing performance. Even when you are out on the road, you're able to make quick and precise adjustments to the brake bias without having to crawl under the dash-a godsend when the packaging is as tight as it is on this particular project. With the tight mounting and clearance issues, we also employed a Kugel Komponents' master-cylinder reservoir kit, and located it off to the side of the master cylinders. By using enough hose, we can remove the reservoirs and fill them while the rest of the pedal assembly is still tucked under the dash, saving us a lot of unnecessary work.

The brakes, drivetrain, chassis, and suspension have all been designed to deliver the best balance and overall performance possible from a street-driven vehicle. While all of this preparation was great, we still needed to consider two important issues: tires and wheels. Without the proper tires to match the level of performance we are looking for, all this work would have been in vain. BFGoodrich tires have been a great high-performance street tire, and we have been extremely happy with their performance over the years. On this project, we did want a little more out of our tires, so an "R" tire looked like the way to go. Since BFG's R tire was still in development, we went with its parent company, Michelin, and used a set of Pilot Sport Cup tires. These tires will maximize our braking potential, while improving our acceleration and lateral-g's. The wheels were lightweight multi-piece forged wheels from Boyd Coddington, specifically made for the backspacing that we required.

How does it all work? Stay tuned for the February issue where we take it to the track and thrash it for real!