Look at how far braking performance has come in the past 50 years. When C1 and C2 Vettes were rolling off the Michigan and Missouri assembly lines more than a half-century ago disc brakes were considered exotic and decidedly European. In due course, Detroit manufacturers concluded that disc brakes were more effective (safer) and cheaper to produce. Fewer parts. Simpler function. Better performance. What wasn’t to like?
Since the advent of disc brakes friction technology has improved dramatically. Brake pads can take the heat better and they outlast their predecessors. When the C4 Corvette was introduced for 1984, its PBR (the original supplier to Corvette) disc brakes at all four corners offered performance unmatched at the time. As with most braking systems from that era, the PBR binders are obsolete compared to what we have from the OEMs today and from the aftermarket.
You may recognize the C2—yes, a 1964—Corvette that we are performing the Wilwood brake swap on. It belongs to Jane Thurmond, and along with her husband Greg’s 1965, graced the cover of a previous issue and had a dual feature inside. It turns out that Jane has her C2 outfitted with a C4 braking and suspension package so we are giving you a heads-up lest you be confused by a C4/C5 brake swap being performed on a C2!
Wilwood offers a fast and quick solution for outdated PBR disc brakes that you can install in an afternoon. The Wilwood SLC56 front four-piston disc brake kit and DPC56 rear four-piston kit enable you to ditch the obsolete PBR disc brakes in a single day and get back into state-of-the-art braking performance you can feel good about. For street, opt for the DP-10 brake pads. If you’re going racing all of the time, consult with Wilwood’s tech staff for advice on which pad to use. The BP-40 and Polymatrix lines of pads enable you to fine-tune brake pad performance.
1. The C4 Corvette suspension and brake system on Jane Thurmond’s C2 chassis is designed to give a classic Vette exceptional handling and stopping power. We’re going to freshen up the braking system up with new Wilwood C5 four-piston disc brakes fore and aft.
2. Would you believe a simple bolt-on C5 brake upgrade for C4 Vettes? Two bolts, disconnect one hose, and these old PBR calipers are off in front. The PBRs were good brakes for their time; however, a quartet of Wilwood’s will yield a night/day difference in braking performance on this C2 Vette sporting C4 suspension.
3. These vintage PBR calipers sport rubber boot dust covers. Because the PBRs tend to get toasty in the kind of brute braking experienced in road racing, the boots are long gone. We also have leakage from at least one of the OEM pucks.
4. Wilwood’s SLC56 front calipers are a high-performance street/race custom replacement for Corvettes and hot rods with the Corvette suspension. These kits offer high-tech styling and performance of the SLC56 calipers with the positive response, long wear, high fade resistance and easy clean properties of the BP-10 compound Wilwood Smart Pads. What’s more, the SLC56 kit is a direct bolt-on replacement for original equipment C5 calipers on all 1997-’04 models and all 2005-’13 C6 base models using the standard 12.8-inch front rotors. The calipers attach directly to the Corvette spindle without the need for adapters.
5. The rotor and hat are assembled as a unit for the front Wilwood SLC56 disc brakes. The bolts should get a high-temperature thread locker such as Loctite 271, which is designed for the permanent locking and sealing of threaded fasteners. You may also use safety wire instead of or in addition to a thread locker. Torque these bolts in a crisscross manner in one-third values up to the final torque spec called for in the instruction sheet.
6. If you are inclined to reuse the existing PBR rotors consider this. Drilled and ventilated brake rotors suffer from weak spots as heat cracking around the holes, which actually weakens the rotor though they’re there to improve cooling and pad off-gassing.
7. When you compare the old PBR rotor (bottom) to the Wilwood SLC56 rotor note that the Wilwood’s cooling fins are directional, which vectors cool air through the rotor to extract heat. Cooling and gas slots reduce and eliminate pressure and heat at the pads. Directional arrows (arrow) make it easy to install these rotors on the correct side.
8. When you’re ordering brake frictions consider how your Corvette will be driven most of the time. Wilwood’s BP-20 pad is what you want for street and autocross use because it responds well in low-temperature street use and it’s kind to iron rotors. The BP-40 and Polymatrix pads are “race only” pads because these pads do their best work under pressure at high temperatures. Because race only pads are very hard and like super high temperatures, they will eat up iron rotors in short order if you run them on the street.
9. The sealed hub C4 spindle makes light work of a brake swap. Once you have removed the PBR caliper and rotor the hub is ready for fresh Wilwood components.
10. The Wilwood rotor has been installed. These are omnidirectional rotors meaning they’re designed to rotate in one direction only for proper cooling. The Wilwood caliper installs with two bolts like the PBR, without adapters or special brackets. Use a low temp thread locker like Loctite 242 Blue on the caliper mounting bolts.
11. We’ve opted for BP-10 Wilwood pads for our street and occasional weekend race C2 sporting C4 suspension and brakes.
12. The rear PBR disc brakes have done their time and it’s time for replacement. Wilwood’s Promatrix one-piece rotor (PN 140-8010-U) and Flexline upgrade kits offer measurable brake performance improvements for racers and enthusiasts using the PBR brake calipers. Here we’re going with the Wilwood four-piston caliper (PN 140-15174-R).
13. The old PBR caliper is easy to remove via two bolts and the hydraulic brake line.
14. The Wilwood one-piece rotor slips onto the C4 hub. The four-piston caliper bolts in place of the original PBR caliper without adapters and brackets. This is a brake swap that’s as easy as changing brake pads.
15. Wilwood offers two types of brake caliper pistons. On the right is the street-suitable piston, which performs very well in street use because brakes don’t suffer the kind of miserable heat torture we see in racing. On the left is Wilwood’s special high-temperature Thermlock piston, which has a hard anodized inner shell and a stainless steel outer shield designed for racing applications where a lot of heat is generated. The piston helps keep the heat out of the O-ring and brake fluid, which keeps destructive heat away from brake fluid, which can boil causing a spongy pedal and ineffective braking performance.
16. Wilwood offers two types of brake fluid: Hi-Temp 570 brake fluid works exceedingly well in street and weekend racing use, and EXP 600 Plus offers super high temperature resistance and performance if you’re going racing and expect grueling brake activity.
17. For autocross and light weekend racing, these Wilwood discs and BP-20 pads deliver optimal effective braking, getting better with heat and pressure. For the street these are the pad you want. For all-out racing, you want the BP-40 race pad. Good brakes contribute to handling as they slow you down quickly in a turn. Happiness is a C2 Vette fitted with C4/C5 Wilwood brakes.
Photography by Steven Rupp