A11 models 848cc (Pre-September 1964)

FootbrakeHydraulic on all 4 wheels
Handbrake (on rear wheels only)Mechanical
Type of brakes – Front and RearSingle leading shoe
Drum diameter7 inch (17.8cm)
Lining Dimensions – Front and Rear6.75 inch by 1.25 inch (17.14cm by 3.17cm)
Lining materialDon 202
Total lining area per brake drum33.75 sq-inch (217.7cm2)
Lining materialDon 202

A11 models 848cc (Post-September 1964) / Riley and Wolseley Hornet from March 1963

As for pre -September 1964 models with the alterations and differences listed below.

Type of brakes – FrontTwo leading shoes
Type of brakes – RearSingle leading shoe
Drum diameter7 inch (1’7.8cm)
Lining Dimensions – Front6.75 inch. by 1.5 inch
Lining Dimensions – Rear6.75 inch. by 1.25 inch

997cc Mini Cooper Models

FootbrakeHydraulic on all 4 wheels
Handbrake (on rear wheels only)Mechanical
Type of brakes – FrontDisc 7 inch (17.8cm) diameter
Type of brakes – RearDrum 7 inch (17.8cm) diameter
Disc pad materialDA3
Lining materialDon 202
Minimum disc pad thickness1/16 inch (1.6mm)

998cc, 970cc, 1071cc. & 1275 ‘S’ type Mini Cooper models

MakeLockheed – with vacuum servo
FootbrakeHydraulic on all 4 wheels
Handbrake (on rear wheels only)Mechanical
Type of brakes – FrontDisc 7 1/2 inch (190.5mm) diameter
Type of brakes – RearDrum 7 1/2 inch (177.8mm) diameter
Disc pad materialDA6
Drum lining materialMintex M.32 or Don 202

Drum Brakes – General Description

The four wheel drum brakes fitted are of the internal expanding-type and are operated by means of the brake pedal, which is coupled to the brake master cylinder and hydraulic fluid reservoir mounted on the front bullhead.

The front and rear brakes of pre-September 1964 models (excluding Cooper and Cooper ‘S’ variants and Mk.Il Riley Elf and Wolseley Hornet models) are of the single leading shoe-type, with one brake cylinder per wheel for both shoes. Attached to each of the rear wheel operating cylinders is a mechanical expander operated by the handbrake lever through a cable which runs from the brake lever to the back- plate brake levers. This provides an independent
means of rear brake application.

The front brakes on post-September 1964 models (excluding Cooper and Cooper ‘S’ variants) are of the two leading shoe -type, with 8 separate cylinder for each shoe. The ends of each shoe are able to slide laterally in small grooves in the ends of the brake cylinders, so ensuring automatic centralisation when the brakes are applied.

Drum brakes have to be adjusted periodically to compensate for wear in the linings. It is unusual to have to adjust the handbrake system as the efficiency of this system is largely dependent OI1 the condition of the brake linings and the adjustment of the brake shoes. The handbrake can, however, be adjusted separately to the footbrake operated hydraulic system.

The hydraulic brake system functions in the following manner: On application of the brake pedal, hydraulic fluid under pressure is pushed from the master cylinder to the brake operating cylinders at each wheel, by means of a four way union and steel pipe lines and flexible hoses. Pressure to the rear brakes is limited by a pressure relief valve fitted in the rear brake pipe line. This reduces the tendency of the rear wheels to lock when braking heavily and weight transfers from the rear wheels to those at the front. When the pressure in the brake line reaches a certain predetermined figure the valve closes and all the additional pressure is transferred to the front wheel cylinders.

The hydraulic fluid moves the pistons out so pushing the brake shoes into contact with the brake drums. This provides an equal degree of retardation on all four wheels in direct proportion to the pressure applied to the brake pedal. Return springs between each pair of brake shoes draw the shoes together when the brake pedal is released.

Drum Brakes Maintenance

Every 3,000 miles, carefully clean the top of the brake master cylinder reservoir, remove the cap, and inspect the level of the fluid which should be 1/4 in. below the bottom of the filler neck. Check that the breathing holes in the cap are clear.

If the fluid is below this level, top up the reservoir with Lockheed Super Heavy Duty Brake Fluid, or a fluid which conforms to specification SAE 70 R3. It is vital that no other type of brake fluid is used. Use of a non-standard fluid will result in brake failure caused by the perishing of the special seals in the master and brake cylinders. If topping up becomes frequent then check the metal piping and flexible hosing for leaks, and che ck for worn brake or master cylinders which will also cause loss of fluid.

At intervals of 3,000 miles, or more frequently if pedal travel becomes excessive, adjust the brake shoes to compensate for wear of brake linings.

At the same time lubricate all joints in the hand-brake mechanism with an oil can filled with Castro- lite or similar.

Drum Brakes – Adjustment

  1. Jack up one side of the car to attend to the brakes on that side.
  2. The brakes on all models are taken up by turning a square headed adjuster on the rear of each backplate. The edges of the adjuster are easily burred if an ordinary spanner is used. Use a square headed brake adjusting spanner if possible. Note:- When adjusting the rear brakes make sure the handbrake is off.
  3. Up to September 1964 one square headed brake adjuster was fitted in each backplate. After this date on models fitted with twin leading shoes two I adjusters per backplate were used. (Front wheels only).
  4. Turn the adjuster a quarter of a turn at a time until the wheel is locked. Then turn back the adjuster one notch so the wheel will rotate without binding.
  5. Spin the wheel and apply the brakes hard to centralise the shoes. Recheck that it is not possible to turn the adjusting screw further without locking the shoe. Note:- A rubbing noise when the wheel is spun is usually due to dust in the brake drum. If there is no obvious slowing of the wheel due to brake binding there is no need to slacken off the adjusters until the noise disappears. Better to remove the drum and blow out the dust.
  6. Repeat this process to the other three brake drums. A good tip is to paint the head of the adjusting screws white which will facilitate future adjustment by making the adjuster heads easier to see.