Thursday 2 July 2015

Automobile Maintenance : Rear Drum Brakes





Rear drum brakes are slowly being replaced by rear disc brakes but they still have their own advantages like they don't tend to stick as the disc brakes do. Had to repair my rear brake for the bi-annual vehicle test. Ask the vehicle test operator about the rating of braking power against which your vehicle would be tested because all vehicles don't have the same braking power. In addition, front and rear brakes have very different braking power and test should be in the similar fashion. If your vehicle is tested against a higher rating, your brakes will certainly be damaged and thats what happened to me (brake cylinder damaged!).  
Before starting, put some bricks or chokes around the front wheels so as to prevent vehicle movement during work on the rear wheels. Use a Wheel wrench to loosen the nuts or bolts (European Vehicles).


You can use a cheater bar to get more leverage.

Use penetrating oil on the bolts that hold the drum. After a few minutes, remove these bolts and remove the drum.

With drum removed, the brake mechanism can be seen.
Clean the drum with brake cleaner fluid.
A close-up of the hand brake cable.

A close-up of auto-wear adjustment system. This adjusts the brake shoes as they wear out so that braking force is not affected. After each intervention on these brakes, this mechanism serves to adjust the brakes so that brake shoes barely drag on the drum when the drum is rotated by hands.
Close-up of the brake cylinder. If it starts leaking (especially after repeated hard braking) then it needs to be repalced.

Inspect the brake cylinder by lifting up its rubber boots and check for oil leakage.
Brake cylinder removed.

New brake cylinder installed with its brake fluid line at the back.
Before rear brake bleeding, it is better to open the brake proportioning valve using a piece of wood. This would facilitate the bleeding process. Dont forget to remove this block of wood after the bleeding is done.
Attach the brake bleeding bottle to the bleed screw. This one is a small bottle with a magnet, so it can be easily placed in tight spots.
Brake bleeding in progress using a two persons method.



Finally, re-check the brake fluid level in the engine compartment and re-fill if necessary.
















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