1964 65 66 67 Ford Mustang Brake Job Guide: Symptoms, Costs and the Right Parts

By Core Brake Parts Tech Team — Circleville, OH warehouse

A brake job on a 1964-1/2 to 1967 Ford Mustang is mostly drum work: most of these cars left the factory with drums at all four corners, and only some V8 cars got the optional Kelsey-Hayes four-piston front discs. The job itself is simple, but on a car this old you are usually replacing shoes, hardware, wheel cylinders and often the master cylinder together, and 1964-1/2 to 1966 cars still run a single-circuit master cylinder that many owners upgrade to a dual-circuit unit while they are in there.

How the Brakes Work on a First-Generation Mustang

The standard setup is a hydraulic drum brake at each wheel. Pressing the pedal pushes fluid from the master cylinder to a wheel cylinder inside each drum, which spreads two brake shoes against the inside of the drum. A star-wheel adjuster between the shoes takes up lining wear; on self-adjusting designs a lever clicks the star wheel outward when you brake in reverse.

What changes from year to year matters when you order parts:

• Lug count. Six-cylinder cars from 1964-1/2 to 1966 are 4-lug; V8 cars are 5-lug. Drums, hubs and disc conversion kits are specific to one or the other.
• Front disc option. V8 cars could be ordered with Kelsey-Hayes four-piston front calipers. Parts for those calipers are different from the single-piston design Ford used afterward, so confirm which caliper your car actually has before buying pads.
• Master cylinder. The 1967 model moved to a dual-circuit master cylinder with a brake warning switch that screws into the distribution block and lights the dash lamp if one circuit loses pressure. Earlier cars use a single-reservoir master cylinder, so one leak anywhere can take out braking at all four wheels.

Symptoms Your Mustang Needs a Brake Job

• Low or sinking pedal. Shoes worn or out of adjustment raise pedal travel. A pedal that slowly sinks while held points to a leaking wheel cylinder or a tired master cylinder.
• Pulling to one side. A seized adjuster, a leaking wheel cylinder soaking one set of linings, or a sticking caliper on disc cars will make the car dart under braking.
• Grinding or scraping. Linings worn to the shoe table or rivets cutting the drum. Stop driving it; the drum may already be past saving.
• Hot drum or burning smell. A drum adjusted too tight, or a parking brake cable that is not releasing, drags the shoes.
• Fluid on the inside of a tire or backing plate. Wheel cylinder leak. The shoes on that wheel are contaminated and must be replaced, not cleaned.
• Brake warning light on a 1967. The pressure switch has seen a difference between the front and rear circuits, which usually means a leak or air in one half of the system.

What a Front and Rear Brake Job Involves

Drum brakes (front and rear on most cars)

Pull the drum, inspect the linings, drum surface, wheel cylinder and springs. On a car this age, plan on replacing the brake shoes, the full return spring and adjuster brake hardware kit, and usually the wheel cylinders. Springs that have spent decades heat-cycling lose tension, and an adjuster that is seized will not keep the shoes close to the drum no matter how new the linings are. Have the drums measured; if one is worn past the limit cast into it, replace it.

Adjustment is where most classic drum jobs go wrong. The self-adjuster is not designed to take up the large gap created by new linings, so turn the star wheel by hand until the shoes drag lightly, then back it off until the drum turns with slight resistance. After the wheels are back on, apply the brakes firmly several times, then back up slowly and brake firmly several times to let the self-adjusters set.

Kelsey-Hayes front discs (optional V8 cars)

The four-piston caliper clamps a pad on each side of the rotor. A brake job means new pads, a check of rotor thickness and runout, and a close look at the four pistons and their seals. These calipers are known for pistons that stick after long storage; a caliper with one frozen piston wears its pads unevenly and pulls. Rebuild or replace the brake calipers in pairs.

Rear axle

The rear is always drums on these cars. The rear shoes do less of the stopping but also run the parking brake, so check that the cable moves freely and the parking brake lever on the shoe is not seized before you button it up.

What to Replace at the Same Time

• Rubber brake hoses. Old rubber brake hoses swell internally and can act like a check valve, holding a brake on. They are cheap insurance on a car this old.
• Hard lines. Inspect steel brake lines for rust, especially along the rear axle and where they clip to the frame.
• Master cylinder. If the fluid is dark, the pedal sinks, or the bore is pitted, replace the master cylinder. On 1964-1/2 to 1966 cars, this is the natural time to consider a dual-circuit conversion.
• Brake fluid. Flush the whole system with the fluid type specified for your master cylinder. Old fluid absorbs water, which corrodes wheel cylinders from the inside.
• Wheel bearings and seals on the front, since the hub comes off anyway on both drum and disc cars.

Upgrading: Dual Master Cylinder and Front Disc Conversions

A front disc conversion is the most common upgrade for these cars. Complete kits for 1964-1/2 to 1966 V8 cars with drum spindles bolt on in place of the drum hardware. A power Kelsey-Hayes style kit, for example, comes with 11.25-inch vented rotors, four-piston calipers, a booster, a dual-reservoir master cylinder and an adjustable proportioning valve, and is built for automatic-transmission cars. A manual (non-power) kit comes with 11.33-inch rotors, a dual-bowl master cylinder and pre-bent 3/16-inch lines. Its maker lists a 14x7 wheel as the minimum and says it also fits 1967 to 1969 six-cylinder spindles, but converts the car to five-lug.

Two points to take from that: a disc conversion is really a system change (master cylinder, valving and lines along with the calipers), and wheel clearance and lug count have to be checked before you order. If you keep the drums, a well-adjusted drum system with fresh hydraulics stops these cars far better than a neglected one, and a dual-circuit master cylinder is the single biggest safety improvement for a 1964-1/2 to 1966 car.

How Hard Is the Job?

Drum brakes on a first-generation Mustang are a good home-garage job if you have spring tools, a way to measure drums, and patience to get the adjustment right. Expect one axle to take an afternoon the first time. Wheel cylinders and flex hoses add time, mostly fighting rusted fittings; use a flare-nut wrench so you do not round them. A dual master cylinder conversion or disc swap is a bigger project because it involves new plumbing and a full bleed. If the pedal is not firm and high when you are done, the car does not leave the garage.

What drives the cost is scope rather than any one part: shoes alone on one axle is the small job, while shoes, hardware, wheel cylinders, hoses, drums and a master cylinder on both axles is a full hydraulic refresh. Shop labor adds the most when seized fittings or lines have to be replaced. Browse our brake parts catalog for the pieces that fit your car.

Frequently Asked Questions

Did the 1965 and 1966 Mustang come with disc brakes?

Front discs were an option on V8 cars, using a Kelsey-Hayes four-piston caliper. Most cars were built with four-wheel drum brakes, so check your car before ordering parts.

How do I tell if my Mustang has a single or dual master cylinder?

Look at the master cylinder on the firewall. A single-reservoir unit has one cap and one outlet line; a dual unit has two chambers and two outlet lines. 1967 cars were built with the dual-circuit type.

Why does my 1967 Mustang brake warning light stay on?

The switch in the distribution block lights the lamp when one circuit loses pressure relative to the other. Look for a leak or air in the front or rear circuit, then bleed the system.

Do new drum brakes need to be adjusted?

Yes. Self-adjusters only take up small amounts of wear, so set the star wheel by hand until the shoes lightly drag, then make several firm stops in reverse to let the adjusters finish the job.

Can I put disc brakes on a six-cylinder 4-lug Mustang?

Yes, but pick a kit made for the 4-lug six-cylinder car or plan on converting to five-lug, which changes your wheels. Confirm wheel clearance first.

Should I replace wheel cylinders during a brake job?

On a car this old, usually yes. A wheel cylinder that starts leaking after the job ruins the new shoes, and they are inexpensive compared to redoing the work.

Sources

1. SSBC-USA A120-20 Kelsey-Hayes conversion kit - 11.25-inch vented rotors, dual master cylinder, proportioning valve, automatic-only fitment for 1964-1/2 to 1966 V8
2. SSBC-USA Mustang conversion kits - 4-lug and Kelsey-Hayes kit fitment by year
3. Leed Brakes 1964.5-1966 Mustang manual disc conversion - 11.33-inch rotors, dual-bowl master, 3/16-inch lines, 14x7 minimum wheel, five-lug conversion note
4. Mustangs Etc 1967 Mustang brake warning light switch - 1967 dual-circuit system and distribution block warning switch
5. Phoenix Systems drum brake self-adjuster guide - self-adjuster operation and initial adjustment procedure