1990 Plymouth Colt Brake Service (ONLINE REPAIR MANUALS)

• Remove caliper assembly as described under "Caliper, Replace."
• Remove bushing from caliper support using slide pin, then cap and pin boot.
• Position a shop towel in caliper body, then apply compressed air through the brake hose fitting hole to remove piston and dust boot.
• Using a suitable screwdriver, remove piston seal.
• Inspect cylinder and piston for wear or damage and/or corrosion. Inspect caliper body and sleeve for wear.
• Install new piston seal into cylinder. The piston seal in repair kit is coated with a special grease, do not wipe it off.
• Apply suitable grease to lip of cylinder,...

The most common cause of brake chatter on disc brakes is a variation in disc thickness. If roughness, vibration, or pedal pulsation is experienced the disc may have excessive thickness variation. Check rotor parallelism (thickness variation) as described under "... "

When the brake pedal is depressed, both the primary (front brake) and the secondary (rear brake) master cylinder pistons are moved simultaneously to exert hydraulic fluid pressure on their respective independent hydraulic systems. The fluid displacement of the two master cylinders is proportioned to fulfill the requirements of each of the two independent hydraulic brake systems, Fig. .

If a failure of a rear (secondary) brake system should occur, initial brake pedal movement causes the unrestricted secondary piston to bottom in the master cylinder bore....

These units are of the vacuum suspended type. Some units are of the single diaphragm type,Fig. , while others are of the tandem diaphragm type,Fig. . Both single piston and double piston or split system type master cylinders are used.

The vacuum suspended diaphragm type units utilize engine manifold vacuum and atmospheric pressure for its power. It consists of three basic elements combined into a single power unit. The three basic elements of the single diaphragm type are:

• A vacuum power section which includes a front and rear shell, a power diaphragm, a return spring...

In order to properly service and repair available brake systems, a thorough understanding of the power assist systems is necessary. The vacuum assist diaphragm assembly multiplies the force exerted on the master cylinder piston in order to increase the hydraulic pressure delivered to the wheel cylinders or calipers while decreasing the effort necessary to obtain acceptable stopping performance.

Vacuum assist units get their energy by opposing engine vacuum to atmospheric pressure. A piston, cylinder and flexible diaphragm utilize this energy to provide brake assistance. The diaph...

Maintenance of disc brakes is extremely critical for proper brake operation due to close tolerances required in machining the brake disc. In addition, the disc rubbing surface must be non-directional and maintained at a micro inch finish to control erratic performance, promote long lining life, and equal lining wear of both left and right brakes.

Refinishing of the rubbing surfaces should not be attempted unless precision equipment, capable of measuring in micro inches (millionths of an inch) is available.

LATERAL RUNOUT CHECK

Refer to "Rotor Specifications" for runout specificati...