Brake Tip 1. Why change brake fluid ?
Here’s a safety tip on brakes. You’ve probably read the advice on brake fluid containers to change your brake fluid every 12 to 18 months and perhaps you’ve thought this is simply so brake fluid manufacturers can make more money! As your brake part specialists (and we don’t have shares in a brake fluid company!) at Brakemart, we believe it is very important you change your brake fluid every 12 to 18 months. You see, brake fluid is “hydroscopic” meaning it absorbs moisture from the atmosphere. If that moisture is allowed to build up, it reduces the boiling point of the fluid and can cause your cylinders to corrode and pistons to seize up – so for safety sake – change your brake fluid regularly.
Brake Tip 2. Testing a brake booster
Here’s a potential money-saving tip on your brake system. A lot of brake boosters come in for servicing unnecessarily through misdiagnosis – but there’s a simple way to test whether your brake booster is working. With your motor switched off, pump the brake pedal about 6 times to empty the vacuum in the booster. Now apply gentle pressure to the brake pedal and start the engine. If the pedal immediately sinks about ½ to ¾”, your booster is working fine. If not, you have a chat to your friendly Brakemart technician – sooner rather than later!
Brake Tip 3. Diagnosing brake problems
The way professional brake mechanics diagnose a poor brake pedal is a method of isolation. Special brake clamps are pinched onto your flexible brake hoses to isolate components. This method will tell you exactly where the problem is.
Brake Tip 4. Running in new Disc Pads
You may have heard of the practice of “bedding in your brakes” – perhaps you’ve done it yourself over the years. Well, disc pad technology has changed and with asbestos-free pads, the practice of riding your brakes and over-heating the new brake pads to bed them in is NOT a great idea – in fact you can actually damage the bonding agents and render the friction material useless. Disc pads are like an engine and have to be run in. Avoid excessive braking in the first 500kms.and you’ll get longer life, better performance and less noise from your brake pads.
Brake Tip 5. Bleeding diagonally split systems (Front Wheel Drive Vehicles)
Ensure the master cylinder is fully primed (bled) before bleeding at the wheels. The order in which bleeder screws are opened is important for X-split systems since all points in one half of the system should be bled before attempting to bleed the other half. Commence with the front brake of the secondary circuit and then the opposite rear. The secondary lines are from the forward section of the master cylinder. Follow this by bleeding the front brake of the primary circuit and then the opposite rear. The primary lines are from the rearward section of the master cylinder (nearest the booster unit of firewall) Ie.
Secondary front caliper
Secondary rear caliper
Primary front caliper
Primary rear caliper
Brake Tip 6. Why wheel cylinders should be replaced when fitting new shoes
Although your wheel cylinders may not be leaking when you replace your worn out shoes, it is normal practice to replace the wheel cylinders at the same time. Let me explain why. As your brake shoes wear, the pistons in the wheel cylinders move outwards to take up the wear in the shoes. As the wheel cylinders are one of the lowest points of a braking system, any moisture built up in the fluid system lies on the bottom of the cylinder and corrodes the wheel cylinder. This is also a great place for any contaminants in the fluid to settle. When you fit your new brake shoes, the wheel cylinder pistons must retract back into the cylinder to compensate for the brake lining thickness and thus placing the wheel cylinder seals into the contaminated and corroded area. Within a short amount of time, the cylinders usually begin to leak over your new brake shoes rendering them ineffective and requiring replacement again. So it pays to do a proper job in the first place. This is caused by the wheel cylinder seals moving over a corroded surface and wearing out prematurely. If your cylinders are sleeved in stainless steel, it would be advisable to at least inspect and replace the wheel cylinder seals.
Brake Tip 7. Overcoming Disc Brake Squeal
Disc brake noise is caused when the vibration frequencies from the disc rotor and the disc pads are similar. It is a fine vibration which is heard as a squeal. One of the ways to help fix this problem is to add some insulation to break the frequency. This is achieved by applying noise suppressants between any metal to metal surfaces of the disc pads. There are numerous types available. If in doubt, consult your Brakemart technician for their recommendations.
Brake Tip 8. Bleeding techniques
If you have a brake hydraulic system that you can’t get all of the air out, “Chocking” of your brake system may be your answer. Your brake fluid may be aerated with very fine bubbles and no matter what you do, you can’t seem to get a reasonable pedal.
Follow these directions carefully and it could solve your problems.
Disconnect your stop lights so your battery won’t go flat
Pump up your brake pedal as high and as hard as you can get it
Chock a piece of timber(or similar) between the brake pedal and the drivers seat to apply constant pressure on the brake hydraulics. This chock will need to be applied for at least two hours – preferably overnight.
Remove the brake master cylinder reservoir lid to allow the air to escape up through the reservoir.
Brake Tip 9. Overfilling your brake fluid reservoir
Here’s another money saving tip from Brakemart. When you top up the brake fluid in your master cylinder, you’ll notice there’s a “maximum level” to fill to. Don’t fill the master cylinder to the very top as during operation, the brake fluid gets hot and expands. When it does, if it has no place to go, the pressure can cause the brakes to “self-apply”, shortening brake friction material life and increasing fuel consumption. The brakes may overheat, causing the brake fluid to boil and you could have a total loss of braking …… so it really is a case of Too Much Is Bad – and if you don’t have a “maximum level” line in your master cylinder, leave about 6mm from the top to allow for expansion.
Brake Tip 10. Diagnosing Uneven pad wear
All disc pads should wear evenly. If you have one pad that is worn a lot more than the rest or uneven, it indicates that there is a problem which must be rectified.
This is usually caused by one of the following:
Seized caliper piston
A sticky or seized caliper slide
Disc pad jamming on side of caliper
Disc rotor surface rough
NB: Because disc calipers operate at high temperatures and are exposed to the elements, special lubricants are used. Consult your Brakemart technician if unsure.
Brake Tip 11. Bleeding a Park Brake type Caliper
If a caliper has been disassembled and requires bleeding after installation, the following advice could save a lot of hassles. Ensure that the park brake lever is in the fully return position against the stop. Better still – disconnect the park brake cables from the levers before bleeding.
Brake Tip 12. Checking and Testing for Faulty Brake Hoses
The most effective way to check for faulty brake hoses is when they are under extreme pressure. Why? Imagine brake hoses are arteries in the human body. A person could live a normal life with hard and restricted arteries but it’s when they expose their heart to some stress problems arise. The same applies to brake hoses. Brake hoses could appear “OK” but when they are subjected to extreme pressure in an emergency is when they need to be in good condition to handle this stress. Most braking systems with booster assisted brakes obtain pressures of approx. 1500 psi. The best method to test brake hoses is to have
The engine running for maximum boost
Have someone pumping the brake pedal while someone is inspecting the hoses.
Hoses are diagnosed by visual inspection and “feeling” the hoses.
Visual Inspection: The things to look for are:
Cracks in the outer “skin” of the hose (Hoses may need to be bent for this test)
Blisters or bubbles in the hose
Chafe marks from where it has been rubbing against something
Any wet marks where a hose is starting to leak
Any obvious bulging or expansion of the hose
Loose hose mounts or twisted hoses*
* All brake hoses have two continuous lines of printing on the hose to make it easy for the installer to indicate if the hose is twisted.
Feeling the Hose
What to feel for (The best way to get the “feel” is to feel a new hose first)
Hard and Stiff hoses
Expansion (This should be hardly noticeable)
Soft and weak hoses