As age creeps up on the C4 generation, components naturally deteriorate, even if the car has been well maintained. This deterioration is accelerated if the car sits for long periods of time, especially if it sits outdoors. Our example is a neglected 1987 Corvette that the Sleeperdude Youtube channel is bringing back to life. This car was a gift from a loyal subscriber of the channel, but it has come with its share of issues. It sat outside for many years, leading to a long list of action items to make it road worthy. Several parts of the process involve the braking system.
This tech article will focus on the brake booster and master cylinder, a common area for corrosion, cracking and other internal issues. From 1985 to 1991, the brake booster on Corvettes was manufactured using plastic. While this was a fine material in mild weather conditions under regular use, the plastic simply doesn’t stand the test of time. Zip Corvette makes reproduction brake boosters, using steel instead of plastic, and it’s a direct bolt-on replacement for all Corvettes built from 1984 through 1991.
The master cylinder fits a much narrower window of cars: 1986 and 1987. Early on, the C4 cars were in a constant state of refinement, so the brake master cylinder changed a few times through the years. The 1986 and 1987 version features an aluminum construction with a small plastic reservoir. Like any older car, the master cylinder is susceptible to corrosion, which keeps it from pushing the fluid properly. Zip Corvette offers a new Master Cylinder, which is an easy solution to refurbishing an aged C4 Corvette braking system.
Follow along as Sleeperdude installs the new brake booster and master cylinder. Simple hand tools are all that’s needed to complete the install, and most enthusiasts can complete this install in the comfort of their home garage as a weekend project.
More than 20 years of neglect has left the booster and master cylinder in this 1987 Corvette in dire need of replacement, but these items can be common areas for problems, even in well-kept cars.The first step is loosening the brake line fittings on the master cylinder. It’s always important to use a line wrench (12mm and 14mm) on the nuts to prevent damage.Next, the master cylinder is removed from the brake booster. It’s held in place with two 13mm nuts that can either be removed with a wrench or short socket and ratchet.The brake booster is held in place with two 13mm nuts that can be found beneath the dash. You may need a combination of extensions and u-joints to reach it with your 13mm socket and ratchet. The retaining pin is also removed from the brake pedal.The new steel brake booster from Zip Products eliminates vacuum issues that plague 1985-1991 Corvettes. This is a direct replacement for the original plastic booster.The booster comes out of the box with new studs and nuts, as well as the proper pushrod. Retain your original pin and clip and reuse on the new install. Another piece of this brake repair job is a new master cylinder. This is a two-year design, used only in 1986 and 1987, and the Zip Corvette product is direct bolt-in replacement of the original.The master cylinder features the original .875-inch bore size, meaning that your C4 Corvette will retain its original pedal effort and performance. Josh removes the nuts off the backside of the booster and slides it into place. The two studs pass through the firewall and brake pedal support bracket. Then, he tightens the 13mm nuts.Under the dash, Josh connects the original retaining pin and clip to attach the brake pedal to the pushrod.Now it’s time to mock up the master cylinder, just to be sure it fits properly, and that the lines are the proper size and in the proper location. It will now be removed so Josh can bench bleed it before final install.With the master cylinder clamped in a bench vise, Josh fills the reservoir with fluid, and attaches a bench bleeding kit from the local parts store.Using a long screwdriver, Josh slowly depresses the piston to push fluid through the clear tubes and back into the reservoir. Once there are no bubbles in the tubes, it is ready to install.The master cylinder easily slides over the new studs on the brake booster. It’s a good idea to get the brake line fitting nuts started before you completely tighten the master cylinder.The 13mm nuts can now be tightened to attach the master cylinder to the brake booster. Zip Corvette offers Pro Line DOT 3 brake fluid with its Brake Overhaul kits. We had enough left over from a previous install to top off the reservoir and begin the bleeding process.Bleeding the braking system starts by pumping the pedal until you feel tension. Then, have a friend or family member hold tension on the pedal and loosen the 10mm bleeder screw to allow any air or dirty fluid to pass through the lines and caliper. Repeat the bleeding until clear fluid comes out.Repeat the bleeding process a few times on each corner, starting at the passenger rear. Then, bleed the driver rear caliper, followed by the passenger front (shown) and driver front, being sure to keep the fluid topped off regularly. After bleeding is complete, fill the reservoir one last time and take a test drive.
Source:Zip Corvette Parts 8067 Fast Lane | Mechanicsville, VA 23111 | (800) 962-9632
