1. Basic Brakes

2. Split systems/dual master cylinders
Used exclusively since 1960’s
Most use front/rear split
Some use diagonal split

3. Brake Fluid Use DOT 3 in virtually all cars
Never ever mix with petroleum based liquids
When cleaning brake parts use only brakeclean, clean brake fluid, or denatured alcohol
Very hygroscopic
Some manufactures recommending flushing intervals

4. Master cylinder Primary piston is acted on by pushrod
Secondary piston is acted on by hydraulic pressure
Each piston will have it’s own:
Compensating port
Vent (relief) port
Return spring
Reservoir

5. Master cylinder diagnosis
Usually fails with one cup bypassing
Low or no fluid pressure from one side of cylinder
Low pedal with brake light coming on
Moisture or petroleum in cylinder will destroy/swell cups

6. Master cylinder repairs
Rebuilding rare today
Most “new” are rebuilt
MUST be bench bled before installation
If done completely system bleeding will not be necessary

7. Power boosters Can be vacuum or hydraulic boosted
Vacuum uses engine vacuum to assist pedal travel
Hydraulic shares power steering pressure off of pump to assist pedal
Both have fail safe if booster fails
Fail-safe will require increased pedal effort

8. Vacuum booster testing
Pedal will fall away when engine started
Will store vacuum for two or three applications
If vacuum leaks off possibly check valve leakage or internal leakage
Brake fluid in booster indicates failed master cylinder and both must be replaced

9. Brake hoses and lines Steel lines are double wall
Use special double flare ISO flare steel or brass fittings
Never use single flare or compression fittings
Hoses
Usually double lined hoses
Lines on hose body should not twist when installed

10. Brake hoses and lines problems
Hoses can balloon only under pressure causing spongy brakes
Inner wall can block off flow/pressure
Metal lines can rust from inside out

11. Common hydraulic valves
Pressure differential valve
Metering valve
Proportioning valve

12. Drum brake Duo-servo vs. non-servo Shoes Drums Primary / secondary
Riveted vs. bonded
Asbestos still around
Drums
Usually cast iron
Must carry heat away

13. Drum brake service Drum removal
Can be rusted around center of drum
Imports may have threaded removal holes
May need to adjust down shoes
If shoes are wet with brake fluid, oil, grease shoes must be replaced
Drums should be resurfaced
All dust MUST be wetted down or vacuumed away

14. Drum brake service
Shoes should be replaced one side at a time for comparison purposes
Usually remove return springs first, hold downs second
Any weak or stretched spring needs new hardware kit

15. Drum brake service Adjuster should be cleaned and lubricated
Baking plate pads need lubrication
Roll back dust boots for inspection
Any grease or brake fluid on shoes should be cleaned off before installation

16. Drum brake problems Squealing when applied Fading Pulsating pedal
Must isolate front or rear
Snapping or clicking noise
Grinding when applied
Low brake pedal
Locked up on very cold days

17. Disc brake Two categories Calipers containing one or two pistons
Fixed
Moving
Calipers containing one or two pistons
Floating caliper and sliding caliper must move freely
Rotors usually cast iron - can be vented or solid
Pads often will have wear indicators

18. Disc brake service Most require R&R of calipers
Slides and pins must be cleaned and lubed
Some pads have anti-rattle plates or require anti-squeak adhesive to back of pads or will have retaining tabs
As pads wear fluid level will drop
Piston must be bottomed in bore
DO NOT allow caliper to hang by hose

19. Disc brake problems Pulsating brakes very common
Binding caliper piston or slides

20. Drum/rotor resurface
Demo on car

21. Brake bleeding
Demo on car