Classic 1965-1967 Ford Mustang Brake Job Guide: Drums, Discs and Master Cylinders

By Core Brake Parts Tech Team — Circleville, OH warehouse

A brake job on a 1965 to 1967 Ford Mustang usually means rebuilding or replacing drum brake parts at all four corners, or servicing the optional Kelsey-Hayes four-piston front discs if your car has them. Before ordering anything, confirm three things: whether the front brakes are drums or discs, whether the car has power assist, and whether it is a 1965-66 car with a single-reservoir master cylinder or a 1967 car with the dual hydraulic system.

How the Brakes Work on a First-Generation Mustang

These cars are simple by modern standards. There is no ABS, no electronic parking brake and no computer involved. The pedal pushes a master cylinder, fluid travels through steel lines and rubber hoses, and wheel cylinders or caliper pistons push the friction material against the drum or rotor.

Most early Mustangs left the factory with drum brakes front and rear. Front disc brakes were an extra-cost option. The 1967 order sheet lists disc brakes as a manual option with the V8 only, lists power brakes separately, and includes disc brakes in the GT Equipment Group for high-performance V8 cars. The same 1967 sheet notes that power drum brakes could not be ordered with the GT group, so a genuine 1967 GT should have front discs.

The factory disc option used Kelsey-Hayes four-piston fixed calipers. Brake specialists such as SSBC still build separate reproduction kits for 1965-1966 cars and for 1967-1969 cars, which tells you the parts are not interchangeable across the whole run. Always shop by model year.

Symptoms That the Brake Job Is Due

• Low or sinking pedal. On drum brakes this is often shoes that have worn and drifted out of adjustment. If the pedal slowly sinks while you hold steady pressure, suspect the master cylinder seals.
• Pulling to one side. A leaking or seized wheel cylinder, a contaminated shoe, or a collapsed rubber hose that holds pressure on one wheel.
• Grinding or scraping. Linings worn to the rivets or backing, cutting grooves into the drum or rotor.
• Wet backing plates or inside tire sidewalls. Brake fluid leaking from a wheel cylinder. Fluid on shoes ruins them; they must be replaced, not cleaned.
• Pulsing pedal. Out-of-round drums or warped rotors.
• Car sat for years. Many of these Mustangs spend long periods parked. Old fluid collects moisture, and wheel cylinders and calipers corrode internally even if the linings look fine.

What Wears and in What Order

On an all-drum car, the front shoes do most of the stopping and usually wear first. Rear shoes last longer but share the parking brake cables, which stretch and seize. On a disc-equipped car, front pads are the fast-wearing item and the four-piston calipers are the parts most likely to need a rebuild, because each caliper has four pistons and four seals that can stick or seep.

Rubber parts age out regardless of mileage. Flexible brake hoses crack on the outside and can swell shut on the inside. On a car of this age, if the hoses are original or their history is unknown, replace them during the brake job.

The Right Parts for the Job

Drum brake cars

• Replacement brake shoes for each axle you service, matched to your drum width.
• Wheel cylinders. Rebuilding is possible, but new cylinders are usually the better choice on a car that has sat.
• A drum brake hardware kit with return springs, hold-downs and adjusters. Old springs lose tension and let shoes drag.
• Drums, if they are scored, cracked, or worn beyond the maximum diameter cast into the drum.

Front disc cars

• Pads specific to the Kelsey-Hayes four-piston caliper for your year.
• Caliper rebuild kits or rebuilt calipers. Check each piston for pitting and sticking.
• Rotors, if they are below the minimum thickness stamped on the rotor or are badly scored.

Both types

• Flexible brake hoses at the front wheels and the rear axle.
• Brake lines where the steel is rusted, kinked or leaking at the flares.
• Fresh brake fluid and a full bleed.

You can browse the wider range in our brake parts catalog. Classic applications vary by year, engine and option, so confirm fitment on each part before you order.

The Master Cylinder Question: Single vs Dual

This is the most important safety point on a 1965 or 1966 Mustang. The factory hydraulic system on these cars is a single-bowl design, so one leak anywhere can drain the whole system and take away braking at all four wheels. For 1967, Ford moved to a dual hydraulic system that splits the car into separate circuits, so a single leak leaves you with partial braking instead of none.

If you are doing a full brake job on a 1965-66 car, it is a good time to consider a dual-bowl conversion. Brake specialist LEED Brakes, for example, sells a manual-brake kit for 1964.5-1966 disc-brake cars with a dual-bowl master cylinder and the lines to reach the factory three-port distribution block. Kits differ by drum or disc, and by manual or power, so match yours carefully. Concours owners may prefer to keep the original single-bowl unit; that is a personal choice, but it should be an informed one.

Whether you keep the original design or convert, the master cylinder must match your brake type. Drum and disc systems need different hydraulic behavior, so a master cylinder for a drum car is not a drop-in for a disc car.

Brake Fluid on a Classic Mustang

Glycol brake fluid absorbs moisture over time. Wagner notes that the fluid also lubricates moving parts and protects against corrosion, which is why old, wet fluid leads to pitted wheel cylinders and sticky caliper pistons. If the fluid in the reservoir is dark, flush the whole system during the brake job.

Do not mix fluid types. Wagner warns never to use silicone DOT 5 in a system built for DOT 3 or DOT 4, and notes that DOT 4 can be used where DOT 3 is specified but not the other way around. Some classic owners do switch to DOT 5, but that means a complete flush and usually new rubber parts, not a top-off.

How Hard Is the Job and What Drives the Cost

A drum brake job is well within reach of a patient home mechanic with basic tools and a spring tool, but it is fiddly. Do one side at a time so the other side stays assembled as a reference. Adjust the shoes after assembly and check that the parking brake releases fully. A disc brake caliper rebuild is harder because of the multiple pistons and seals.

What moves the cost is the scope. Shoes and hardware on one axle is the smallest job. Adding wheel cylinders, drums, hoses and a flush on all four corners raises the parts count and the labor. A disc car needing rebuilt four-piston calipers adds more, and a dual master cylinder conversion or a full brake line replacement is its own project. Getting a price for pads or shoes alone versus a complete refresh is the clearest way to compare quotes.

Torque the wheel lug nuts and any caliper or bracket bolts to the values in the factory shop manual for your year, and road-test gently before driving normally.

Frequently Asked Questions

How do I tell if my 1965-1967 Mustang has front disc brakes?

Look through the wheel or pull a front wheel. A disc car has an exposed rotor with a large caliper bolted over it. A drum car shows a closed drum with a backing plate behind it.

Can I put disc brake parts on a car that came with drums?

Yes, brake specialists build Kelsey-Hayes style conversion kits for these cars. The master cylinder and hydraulic valves usually need to change as well, so buy a complete kit made for your year rather than mixing parts.

Is my 1967 Mustang a dual-circuit car?

The 1967 Mustang used a dual hydraulic system from the factory. If a 1967 car has a single-bowl master cylinder today, someone has changed it and the system should be checked.

Should I replace the rubber brake hoses even if they look fine?

On a car this old, yes, unless you know they were replaced recently. Hoses can deteriorate inside and restrict flow while looking acceptable outside.

Why do my brakes pull after sitting all winter?

A wheel cylinder or caliper piston has likely stuck from corrosion, or a hose is holding pressure. Inspect each corner and replace the sticking part along with its opposite side.

Sources

1. MustangSpecs 1967 Ford Mustang guide - 1967 dual hydraulic system; optional disc brakes with power assist; discs in GT group
2. Over-Drive Magazine 1967 Ford Mustang fact sheet - disc brakes V8-only option; power drum brakes not available with GT group
3. SSBC Kelsey-Hayes Mustang kits - Kelsey-Hayes 4-piston front disc kits split by 1965-1966 and 1967-1969
4. LEED Brakes 1964.5-1966 Mustang hydraulic kit - factory single-bowl system; dual-bowl conversion to the three-port distribution block
5. LEED Brakes 1967-1969 Mustang hydraulic kit - dual-bowl master cylinder and adjustable rear valve for manual brake cars
6. Wagner Brake: facts about brake fluid - fluid moisture and corrosion role; DOT 3, 4, 5 compatibility rules