1978-1979 Buick Century Front vs Rear Brakes: What Wears First and What to Replace

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 1978-1979 Buick Century, the front disc brakes wear out first, and usually by a wide margin. The rear drums do far less of the stopping, so rear shoes commonly outlast two or more sets of front pads. What goes wrong at the back is less about friction wear and more about adjustment, leaking wheel cylinders and tired hardware.

This guide explains why the wear splits that way on the downsized Century, how to tell which end of the car needs attention, and what to replace together so the brakes stay balanced.

How the Brakes Are Laid Out on the 1978-1979 Century

The 1978 redesign put the Century on a smaller, lighter rear-wheel-drive platform, but the brake layout stayed the classic GM setup of the era: disc brakes up front and drum brakes at the rear. NHTSA records confirm the rear drum arrangement directly. Recall campaign 85V048000, which covers the 1978 Century, describes the wheel cylinder mounted in the rear brake backing plate, which is the hallmark of a drum brake.

Up front, a caliper squeezes a pair of pads against the rotor. The rotor rides on serviceable, grease-packed front wheel bearings on the spindle, which matters whenever you take the front brakes apart (more on that below).

At the back, each wheel carries a pair of shoes inside a cast drum. A wheel cylinder pushes the shoes outward, return springs pull them back, and a star-wheel adjuster keeps the shoes close to the drum as the lining wears.

Why the Front Brakes Wear First

Every time you brake, the car's weight shifts forward. Wilwood's engineering explanation puts it plainly: because braking moves most of the vehicle's weight onto the front wheels, the harder you stop, the less traction the rear tires have. The front tires can use more braking force, so the front brakes are sized and plumbed to do most of the work.

The hydraulic system is built around that. A proportioning valve limits pressure to the rear brakes once line pressure passes a set point, so the rear drums do not lock up in a hard stop. Drum brakes are self-energizing, meaning the rotating drum pulls the shoe tighter into it, and Wilwood notes that drums lock up at a much lower pressure than discs. Holding the rear back is a safety feature, but it also means the rear linings see less work and last longer.

GM disc/drum cars of this period also used a metering function that delays front pressure slightly until the rear shoes overcome their return-spring tension, so both ends engage together in light stops. Even with that help, the front pads carry the load in almost every real-world stop.

Symptoms: Which End Needs Attention?

Front disc brake signs

• Squeal or scraping on light braking - pads near the end of their lining, or metal-to-metal contact if ignored.
• Pulsation in the pedal or steering wheel - uneven rotor thickness, often from heat or a rotor worn below its minimum thickness.
• Pull to one side - a sticking caliper piston or slide, or a collapsed flexible hose on one side.
• Grinding and deep grooves in the rotor face - pads worn to the backing plate. At this point the rotors need replacing, not just new pads.

Rear drum brake signs

R1 Concepts lists the classic failed-adjuster symptoms, and they match what a Century owner will feel:

• Low or spongy pedal that improves if you pump it - shoes too far from the drum.
• Parking brake lever or pedal travels too far before it holds.
• Pull to one side under braking - one rear adjuster seized, or one wheel cylinder leaking.
• Scraping or grinding from the rear - shoes worn through, or a broken spring letting a shoe drag.
• Wet inside of the tire or backing plate - brake fluid leaking from a wheel cylinder. Fix it immediately; fluid on the linings ruins them.

The Rear Drum Recall Every Century Owner Should Know

NHTSA campaign 85V048000 covers the 1978 Buick Century. The record states that excessive enlargement of the wheel cylinder pilot hole in the rear backing plate could let the wheel cylinder rotate and lose brake fluid, which leads to loss of rear brake action. The remedy was to add a part that stops the wheel cylinder from turning.

On a car this old, you cannot assume that fix was ever done or that it survived later brake jobs. Whenever the rear drums are off, check that each wheel cylinder is tight against the backing plate and cannot rotate, and that the brake line fitting is not twisted or seeping. If the backing plate hole is worn, the backing plate or retaining hardware needs attention before the new wheel cylinder goes on.

A second recall on the 1978 Century, 79V175000, involves the front wheel outer bearing. NHTSA notes that heat in that area could affect the bearing grease, and inadequate lubrication could lead to failure of the bearing and the spindle. The remedy was new outer bearings packed with grease. Because the front rotors ride on those bearings, a front brake job is the natural time to inspect, clean and repack them.

What to Replace Together

Front brake job

• Pads in axle sets - always both sides. Our Hawk HPS 5.0 front brake pads for the 1978-1979 Buick Century Custom are a performance street compound; confirm year, trim and brake package before ordering. Browse more options in our brake pads and ceramic brake pads collections.
• Rotors if they are grooved, pulsing or below the minimum thickness cast on the rotor. See brake rotors.
• Front wheel bearings and seals - clean, inspect and repack or replace, and fit a new grease seal.
• Calipers if a piston is sticking, a boot is torn or the caliper leaks. Replacement units are in our brake calipers collection.
• Flexible hoses if cracked or swollen; decades-old rubber can collapse internally and hold a caliper on. See brake hoses.

Rear brake job

• Shoes in axle sets from our brake shoes collection.
• Hardware kit - return springs, hold-downs and adjuster parts lose tension with age and heat. A brake hardware kit is cheap insurance.
• Wheel cylinders - if there is any dampness under the dust boots, replace them. On a car of this age, many techs replace them by default.
• Drums if scored, cracked, or worn past the maximum diameter stamped on the drum.

If the pedal stays low after both ends are serviced and bled, suspect the master cylinder. Our master cylinders collection covers replacements; bench-bleed a new unit before installing it.

How Hard Is the Job?

The front brakes are a good first job for a home mechanic with jack stands, a piston tool, and basic hand tools. The extra step on this Century is the wheel bearing service: removing the rotor means pulling the dust cap, cotter pin and spindle nut, then setting bearing adjustment correctly on reassembly per the factory service manual.

The rear drums take more patience. There are several springs to move, and the self-adjuster has to go back together in the right orientation. Phoenix Systems' procedure is the one to follow afterward: expand the star wheel until the shoes lightly drag, then make firm stops in reverse to let the adjuster take up the rest. As they point out, self-adjusters only work when there is enough shoe travel to activate them, so a badly backed-off adjuster needs a manual start. Do one side at a time so the other side stays assembled as a reference.

After any hydraulic work, bleed the system with the fluid type shown on the master cylinder cap or in the owner's manual, and torque caliper and wheel fasteners to the values in the factory service manual.

Frequently Asked Questions

How many sets of front pads will I use before the rear shoes wear out?

There is no fixed ratio, but on a front disc, rear drum car like the Century, the front pads wear much faster because they do most of the stopping. It is common for rear shoes to outlast multiple front pad sets. Inspect the rear shoes and hardware every time you do the fronts.

Can I replace only the front brakes and leave the rear alone?

Yes, if the rear shoes have lining left, the adjusters work and the wheel cylinders are dry. Pull the drums and look before deciding. A leaking wheel cylinder or seized adjuster makes the fronts work even harder.

Why does my Century's parking brake barely hold?

Usually because the rear shoes are out of adjustment. The parking brake uses the rear shoes, so if the star-wheel adjusters have not been advancing, the lever travels a long way before the shoes reach the drum. Adjust the rear shoes first; only then adjust the parking brake cable if needed.

Should I convert my 1978-1979 Century to rear disc brakes?

For a daily or cruise car, a properly rebuilt factory drum system stops the car well. Any conversion changes the front-to-rear balance the proportioning valve was set for, and Wilwood warns that mismatched systems can lock the rear wheels. If you convert, the valving has to change with it.

Is the wheel cylinder recall still relevant on a car this old?

The recall records are still worth reading, because the failure they describe, a wheel cylinder rotating in a worn backing plate hole and leaking fluid, can still happen. Check that each rear wheel cylinder is solidly located whenever the drums are off.

Sources

1. NHTSA recall records, 1978 Buick Century - campaign 85V048000 (rear wheel cylinder rotation and fluid loss) and 79V175000 (front wheel outer bearing)
2. Wilwood - How does a proportioning valve work? - weight transfer, rear lockup, drums locking at lower pressure than discs
3. First Place Auto Parts - GM proportioning, metering and combination valves - metering and proportioning functions on GM disc/drum cars
4. R1 Concepts - How do self-adjusting drum brakes work? - star-wheel adjuster operation and failure symptoms
5. Phoenix Systems - Adjusting rear drum brakes with self-adjusters - manual start and reverse-stop adjustment procedure