Notes, Warnings, and Hints
DRUM REMOVAL
The drum should just slide off however it will often bind or stick for the following reasons:
Excessive Grooves or Scoring - The interlocking grooves prevent the drum from sliding off.
Uneven Wear - Uneven wear across the surface of the shoe creates a wedge which prevents the drum from sliding off.
Lip or Edge - Commonly there will be a lip worn at the edge of the drum where the shoe to drum contact stops.
NOTE: If both drums are stuck tightly, verify the parking brake is released.
To remove a drum which is stuck you should retract the shoes by backing off the automatic adjuster.
If the drum still will not slide off there may be corrosion between the drum and hub. A few sharp blows from a mallet or hammer along the front flat surface of the drum will usually free the drum.
WARNING: Prying off a stuck drum with a puller or pry bar can damage the springs or hardware. Always attempt to withdraw the shoes with the automatic adjuster first.
Once the drum is removed a layer of brake dust will remain in the bottom of the drum. This dust should be thoroughly soaked with water or brake cleaner and then removed from the drum.
WARNING: Inhaling brake dust is extremely hazardous to your health.
PRIOR TO REMOVING THE SHOES
- Clean the shoes, hardware, and backing-plate thoroughly for the following reasons.
- Initially the springs will appear black (from brake dust). The springs are actually color coded and it is very important to reinstall the springs in the correct location.
- The shoes and hardware will need to be cleaned to determine if an overheating condition has occurred (discolored bluish-purple).
- Inhaling brake dust is VERY HAZARDOUS TO YOUR HEALTH.
WARNING: Do not use compressed air to clean the brake assembly.
- Verify the new brake components exactly match the old ones.
BRAKE SHOE REMOVAL
- If there is any possibility that the shoes may reused, remove any drip pans that may be under the brake assembly and handle the shoes carefully when removing.
NOTE: WORK ON ONE SIDE AT A TIME (unless you are very familiar with the system). The other side may then be used as a model for reassembling.
WHEEL CYLINDER REMOVAL
- Wheel cylinder retaining bolts, brake line fittings, and bleeder screws are often heavily corroded. Prior to starting the job you should spray these with a penetrating oil.
- A line (flare nut) wrench should be used when loosening the brake line fittings. These fittings round off easily.
WHEEL CYLINDER OVERHAUL
- Light amounts of corrosion within the cylinder bore and on the piston may be removed with crocus cloth.
- Pitting and heavy corrosion should be removed with a hone. When honing the hone should be inserted and withdrawn quickly to achieve a 45 degree crosshatch.
- Closely inspect the areas of the cylinder where the pistons seals contact. It is very important these areas are absolutely free of deposits, corrosion, or pitting.
- Remove the bleeder screw and verify that the passage is clear.
- Leave the bleeder open when installing pistons and cups into the cylinder bore. If the bleeder is closed a large amount of air will be forced into the brake lines.
- Use brake assembly lubricant to coat the cylinder bore, pistons, and cups. Clean brake fluid is an acceptable lubricant when assemblying the wheel-cylinder but brake assembly lubricant is much slicker and minimizes the chance that the cups will be damaged.
WARNING: Do not use a petroleum based grease or oil to lubricate the wheel-cylinder components. This will cause the seals and cups to swell and deteriorate.
- When reassemblying the wheel-cylinder it is helpful to follow this sequence:
1. Rear cup (verify the cup is inserted properly, flat side towards the piston, concave side towards the center)
2. Rear piston
3. Rear dust cap (this prevents the rear cup and piston from popping back out when the spring and front components are installed).
4. Spring
5. Front cup
6. Front piston
7. Front dust cap
WHEEL CYLINDER INSTALLATION
- Attach the brake fluid line fitting loosely to the wheel-cylinder prior to inserting and tightening the retaining bolts. The brake fluid line fitting is much easier to attach and start turning with the wheel-cylinder loose.
WARNING: Don't forget to tighten the brake line fitting after the retaining bolts are tightened.
- Leave the wheel-cylinder bleeder screw open and place a drip pan under the rear brake assembly. Refill the master-cylinder with new brake fluid and let the fluid gravity bleed through the open bleeder screw. When brake fluid begins to drip from the bleeder, close the bleeder screw.
NOTE: The brake system will still need to be flushed and bled, but this makes starting the process much easier.
BRAKE SHOE INSTALLATION
- Clean and lubricate the backing-plate contact pads with a high temperature silicone lubricant.
- Any contamination should be removed from the new shoes immediately. If very light hand sanding will not remove the contamination the shoes should be discared.
- When replacing shoes/linings or drums always replace both sides per axle. If only one side is replaced a steering pull may develop during braking.
- If brake hardware is being replaced, verify that both the color and shape of the new springs match the old springs.
- Prior to reinstalling the drum, the automatic adjuster will need to be backed off to accommodate for the increased thickness of the new shoes/linings.
DRUM INSTALLATION
- Prior to installing the drum verify the automatic adjuster operates properly and that the tools you are intending to use to adjust the brakes will be able to reach the adjuster.
- With the drum off, practice operating the adjuster through the access hole in the backing-plate. This will make adjusting the brakes much easier once the drum is installed.
- Ensure the shoes/linings are centered on the backing-plate (top to bottom and side to side). The drum will be very difficult to slide on if the shoes/linings are not centered.
- If the drum was resurfaced, verify that all metal shavings have been removed.
- If the wheel cylinders were replaced or overhauled, verify that the pistons are fully compressed. Newly installed or rebuilt wheel cylinders may initially stick in the extended position (prior to bleeding the system). Using brake assembly lubricant when overhauling the wheel-cylinder will help prevent this.