Find Best Rear Brake Hydraulics

Using a fluid under pressure to transfer motion or force or to increase the applied force is known as ‘Hydraulics’.

The system that uses various components for braking action by the help of hydraulics on rear wheels is known as ‘Rear Brake Hydraulic system’ or ‘Rear Brake Hydraulics’.

Usually, the brake fluid used is a mixture of Alcohol or castor oil and Glycerine and some additives.

Hydraulic brakes work on the principle of Pascal’s law. The law states that the pressure at any point in the enclosed fluid will exert the same at all directions.

It is the hydraulic pressure that forces the brakes to actuate its operation.

Rear brake hydraulics is basically associated with the Drum brake mechanism at rear wheels.

The rear hydraulic braking system mainly comprises:

• Brake pedal
• Brake fluid reservoir
• Master cylinder
• Wheel cylinder
• Brake drum
• Brake shoes
• Brake fluid with brake line

Brake Fluid - It is a chemically inert hydraulic fluid used to transfer force or motion. It also lubricates pistons in the master cylinder and wheel cylinders in brakes.

There Are 3 Types Of Brake Fluid:

1. DOT 3 - This is common and most widely used.
2. DOT 4 - This is mainly produced for disc brakes for higher temperatures than drum brakes.
3. DOT 5 - This type is silicone based and can take even higher temperatures.

DOT 3 and DOT 4 are hygroscopic, and they absorb moisture. They have a clear to amber colour. DOT 5 is incompatible with DOT 3 and 4 fluid and cannot be mixed with them. DOT 5 has a purple colour.

Brake Lines:

Brake lines are also called hydraulic lines. It is a kind of pipe that contains a passage for brake fluid to pass from master cylinder to the wheel brakes. Basically, brake lines are made of steel. A small flexible brake hose connects the steel brake lines to the wheel cylinders.

Here are the features which you should look into while purchasing rear hydraulic brake kit:

• It should have increased braking effort as compared to mechanical brakes.
• The system should be convenient and flexible to mount.
• Self-compensating systems as pistons of wheel cylinders should expand according to their desire, compensating the system automatically.
• Self-lubricating system as brake fluid should be used, which eliminates the use of any extra lubrication system.

Have a look at the steps below to know the working of the rear brake hydraulics:

• When the brake pedal is pressed, the oil from the master cylinder on the piston side forces the oil in the brake line.
• Thus, brake fluid is forced from the master cylinder into the brake lines to the wheel brakes. This increases the hydraulic pressure of liquid.
• Then, oil flows in the hydraulic brake system where the piston of the wheel cylinder is pushed outwards and presses the friction material pad or shoes against the drum.
• Because of this spring gets expanded, and it applies brakes to slow or stop the vehicle.
• As the brake pedal is released, the piston in the master cylinder gets back to its original position because of the return spring attached, also dropping fluid pressure.
• This brake shoe retracting spring pulls the brake pads or shoes from the brake drum to their initial original position.
• Thus, the correct fit brakes are released and the wheels of the vehicle can again start rotating to move the vehicle.

The system of rear hydraulic brake comprises brake lines connected from master cylinder to the wheel cylinder of the drum brakes. So, there are some common problems that occur in the brake's loading hydraulics system. They are as follows:

1. Air In The Hydraulic System - This is the major problem that occurs in most of the cases. Air gets trapped in the hydraulic system, which causes less braking effort for a vehicle. The air may get in because of a low fluid level in the master cylinder. This leads air to be forced into the system as the master piston moves forward during braking. This air can be removed by bleeding and by adding brake fluid.
2. Clogged Brake Line - Sometimes the hydraulic line gets clogged because of impurities, debris or any other reason. Therefore, a clogged brake line will not release pressure from the wheel cylinder. This leads to a piston in the wheel cylinder sticking in its applied position, which further doesn’t allow the shoe to move away from the drum when brakes are released. As a result of which the brake drags.
3. Loss Of Brake Fluid - Any leakage in the system leads to loss of brake fluid. It can occur from the master cylinder, wheel cylinders, brake lines and connections. This leads to lack of braking action in a car.
4. Bent Master Cylinder Push Rod - There may be a bent master cylinder push rod if an outrageous amount of force is applied on it. This leads to loss of pedal reserve.
5. Damaged Hydraulic Or Brake Line - Whenever there is damage in the brake line it leads to loss of hydraulic fluid, which further troubles the driver to apply brakes. This cut-off the supply of flow of fluid to all wheel cylinders and hence, the brake fails.

A complaint of faulty brakes should be immediately diagnosed to determine its cost. When the driver depresses the brake pedal, hydraulic pressure forces the brake lining against the drum. The resulting friction and heat cause the brake parts to wear.

Warning lights, wear and fluid level indicator in a vehicle helps to alert the driver about the brake inspection and service.

1. Soft And Spongy Brake Pedal - Air in the hydraulic system causes a soft pedal, by which a vehicle doesn’t get complete braking power to lock the wheels. Even loss of brake fluid in the system causes soft pedaling, which leads to brake losses.
2. Low Level Of Brake Fluid - Whenever there is low level of fluid in the master cylinder reservoir, it shows to inspect whether there is any kind of leakage of fluid from the system and fix it. On a regular basis, after a certain period, we should top up the brake fluid in the reservoir or when brake's service is done.
3. Brakes Drag - Brakes drag is a symptom which shows that there is a blockage in brake line or defect in the master cylinder. Dragging can also be caused by swollen seals or cups in the master cylinder.

Is it necessary to go to a mechanic or technician every time for just brake bleeding of rear brakes? Well, it’s not ! We can do it ourselves if we have some basic tools for brake bleeding. Some primary tools are:

• Wrench Set
• A hose / pipe
• Brake Fluid
• Transparent container / jar / bottle
• Torque Wrench
• A helper

Choosing a brand for any part of the braking system plays a very important role as brakes act as a safety system in a vehicle, and that is the reason brake failure should be taken care of. So, we made it very simple by selecting some top brands which manufactures rear brake hydraulic system parts.

• Raybestos Rear Brake Hydraulics
• Dorman/Help Rear Brake Hydraulics
• H Paulin Rear Brake Hydraulics
• Dorman/First Stop Rear Brake Hydraulics
• Dorman/Autograde Rear Brake Hydraulics
• Beck/Arnley Rear Brake Hydraulics

Now we got an idea about the rear brake hydraulics so lets see some related components with it.

• Rear Right Wheel Cylinder Bracket
• Rear Brake Hose
• Rear Bleeder Screw

We must bleed the hydraulic system to remove the air trapped in it. Bleeding is also required if connections have been loosened or opened during service work. If not done, then this can allow the air to enter the system.

Bleeding is a 2 person job so take your friend’s or partner’s help to bleed the brakes.

Steps:

• First provide a ram or car jack below the car and lift it up to a certain height where rear brake service can be done easily.
• Then loose the lug nut attached to the rear wheels and remove the wheels from the hub.
• Remove the drum cover and locate the bleeder valve.
• Make sure that it fills the master cylinder reservoir with brake fluid, if not then top up it with required brake fluid used.
• Use a box-end wrench or ring spanner of particular size that fits on a bleeder screw to loosen it for bleeding.
• Now, connect the one end of a hose / pipe to the bleeder valve of one rear wheel brake and the other end that is lower end put it in a transparent container / jar partly filled with clean brake fluid.
• Now, keep the bleeder valve in a closed position by using a wrench. Then tell your partner to sit in the driver's seat and start pressing the brake pedal continuously for a while.
• Then stop him to push the pedal after a few seconds and make him hold the pedal. Now, loose the bleeder screw for 1 or 1/2 turns so that the fluid will flush out in the hose to the transparent jar.
• Now, we can absorb some air bubbles in the hose coming out after opening the bleeder screw, then close the bleeder screw and again start pushing the brake pedal for a few seconds and repeat this procedure to tighten and loosen the valve for removing air from fluid.
• Do this till we see the clean fluid passing through the hose. Also, follow the same steps for another rear wheel brake.
• Once the bleeding is done we can feel that the soft brake pedal or loose pedal has become little hard to operate and braking action is accomplished completely.
• By following this simple procedure, anyone can perform bleeding in rear brake hydraulics and fix braking themselves, even without spending much money.