Isnin, 25 Februari 2013

DIY: Brake Bleeding made easy and explained!

Here is a simple DIY on bleeding your brakes in an easy way that requires just a few simple tools, and a casual volunteer.

Ever since the first cart on wheels came along, mankind began its quest for more speed. And once he had achieved that and when he started to crash into looming obstructions ahead, he realised the importance of what everyone today expects to work without issue - braking. And like any other bits that make your vehicles work, braking systems require occasional maintenance.

This speed-shedding mechanism has two items that will need attention after a period of time; first is the brake pad for disc brakes or shoes in drum variants, the second is the brake fluid that runs from the engine bay to each wheel. Because of the brake fluid line’s length, amount of connections, and hygroscopic (water absorbtion, in layman terms) nature of brake fluid, it is vital for the whole system to be contaminant-free of water and air bubbles to maintain a consistent amount of pressure when the paddle is depressed.

But what if the brakes feel spongy even though you are sure it is leak-free and without any mechanical failure? Well that is when bleeding your brakes comes in handy; a process of flushing out existing fluid out through the nipple with new, clean fluid. Here is a simple DIY on bleeding your brakes in an easy way that requires just a few simple tools, and a casual volunteer.

Tools needed

  • Closed end spanner: The main reason this is suggested over an open-ended variant is because a rusted nipple-nut combined with a loose grip will likely strip the nipple-nut
  • One or two bottles of fresh brake fluid: Take note of the existing fluid specification, eg. DOT 3, DOT 4 etc. as different grades have different boiling points and thus should never mix
  • A length of clear flexi tube that would fit over the nipple: I used the conventional aquarium air tubes from pet stores but widened by heating up the end that would go over the nipple.
  • Empty bottle as a retainer for the drained fluid
  • Anti-rust e.g. WD40 or RP7
  • Water to wash off spillage
  • Tire removing tools and jack-stands

Old fluid retainer preparation process

  1. With the cap removed, make a hole big enough for the flexi tube
  2. Insert the smaller end through the cap before screwing back onto the bottle

    Old fluid container

Bleeding process

1. Remove and wheel and secure the raised vehicle on jack stands

2. Remove the cap on the nipple before spraying some anti-rust onto the nipple-nut

3. Fit the spanner over the nipple-nut and make sure it can be loosened

Fit the spanner first

4. Fit the wider end of the tube over the nipple

5. Make sure brake fluid reservoir is at maximum level and top up if necessary
6. Ask your helper to step into the driver’s seat and pump the brakes before keeping the paddle down

7. While the brakes are applied, loosen the nipple nut to release the fluid through the tube. Tighten it again once the flow has stopped.
8. Continue steps 6 and 7 for 5 times and re-check the reservoir after each cycle. Do until the fluid within the tube appears clear without contaminates and bubbles. The paddle should feel firmer with each cycle.
9. Clean any off any spillage, fit back the nipple-cap and the rest of the items before putting the vehicle back on the ground and secure the wheel nuts onto the wheel.
10. Finally, make sure the brake fluid reservoir is fully topped up before repeating the whole procedure for all other wheels.

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