1. Drum Brake Overhaul Roger Bortignon

2. Drum Removal hubless drums slide right off
often they may have to be tapped with a hammer to free them up
some imports have 2 threaded holes
install two 8mm bolts to pull the drum off
drums with integral hubs
remove dust cap
unlock retaining nut
remove washer & bearing

3. Drum Brake Replacement & Overhaul
items that will need inspection, service or replacement include…
Friction parts
brake shoes
brake drum
Hydraulic parts
wheel cylinder & brake fluid
Hardware
emergency brake cables
brake return springs

4. this is NOT a step-by-step procedure
every vehicle is slightly different
experience & personal preference dictates the order for re & re

5. Brake Shoe Removal
clean brake assembly by wet washing – use a dust mask
use brake washer – if on the hoist
or use spray bottle with soapy solution set to mist
do NOT use compressed air on dry brake assembly!
remove upper return springs

6. Brake Shoe Removal – Special Tools
use brake spring pliers, not screwdrivers or general purpose pliers – easier, safer & quicker

7. Brake Shoe Removal
remove hold down springs (may require special tool – fig.a)
unhook e-brake cable (see next slide)
remove shoes
fig. a

8. Emergency Brake Cable Removal

9. Wheel Cylinders – what should I do with it?
has the brake fluid been flushed out every 2 years?
is it leaking?
how old is the vehicle?
should I leave it alone?
rebuild or replace?

10. Rebuilding Wheel Cylinders
loosen the bleeder screw – this is important
cast iron cylinders can be honed
aluminum cylinders should only be cleaned & not honed
use brake fluid when honing
hone only enough to clean cylinder
(≈10 seconds)
ensure there is no pitting where the cup seals slide

11. Rebuilding Wheel Cylinders
replace cup seals (note diameter) & dust boots
use clean brake fluid or rubber lubricant to assemble
reassembly – cups on seals face inward

12. New Wheel Cylinders
notice new brake line – olds ones often twist when you loosen them
use a flare nut wrench to loosen & install hydraulic lines

13. Lubricate Shoe Support Pads
use anti-seize compound on the 6 shoe support pads
this will reduce/eliminate brake squeal
if the pads are grooved
replace backing plate, or…
mig weld grooves then grind smooth

14. Test Emergency Brake Cables
apply & release e-brake while watching the cable move in & out of its’ housing
any “laziness” or binding = cable needs replacing

15. Service Brake Adjuster
disassemble, clean threads & lubricate with anti-seize compound
some imports use a wedge to spread the shoes apart
pay attention to the ends of the adjusters
ensure you understand how they are to be assembled
brake adjusters are side-specific – don’t mix up the left & right sides!

16. Reinstall Brake Shoes install new shoes
use new hold down pins & springs if needed
dual-servo brakes (p ) will have unequal length brake shoes
short shoe (primary) on the front side of the axle
long shoe (secondary) on the back side of the axle

17. Install Upper Return Springs
non-servo (leading-trailing) brakes will have a solid anchor at the bottom and equal length brake shoes
replace the springs if rusted, kinked, bent

18. Drum Inspection & Reconditioning
conditions that require drum machining…

19. Drum Inspection & Reconditioning
use a drum micrometer and check for oversize
if drum is smooth and in otherwise good condition, simply deglaze the brake surface with emery paper
machine drum if it is not oversize

20. Adjusting Brake Shoes
brake shoes will self-adjust for wear during normal operation
some self-adjust when you back-up the vehicle
others self-adjust when you apply the hand brake
use a brake shoe setting gauge for initial adjustment after replacing the brake shoes
manipulate the adjuster (screw type or wedge) so that the shoes will just contact the drum

23. Adjusting the E-brake
after the brake shoe-to-drum clearance has been adjusted, the e-brake cables can be adjusted if needed

24. Wheel Bearing Service
if bearings were removed, repack them with fresh wheel bearing grease & replace the grease seals
refer to chapter 34 in Halderman

25. Bleed / Flush Brake Fluid
if the hydraulic lines were disconnected or the wheel cylinder was replaced/overhauled air has to be removed from the brake system as well as flushing out the old brake fluid

26. Road Test the Vehicle ensure the pedal is high & firm
no noises or squeaks
e-brake travel is correct amount
no brake fluid leaks at the wheel cylinder, line or bleeder valve

27. In the High School
take a digital picture of the brakes before disassembly
place the pic on shop computer’s desktop for reference
print a diagram from Mitchell
finish one side, then start the other side
ensure you have sufficient time to complete the repairs