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Mason Shields, October 8 2019

Brakes - Coming to grip with them

What do brakes do?

Brakes are in the car for one reason.  To stop the vehicle from moving.

How do they do that?

When you press down on the brake pedal that moves a piston in the master cylinder that forces brake fluid to each wheel.  At each wheel, you have either a caliper for disc brakes are a wheel cylinder for drum brakes.  The caliper and wheel cylinder each have a piston that moves under pressure.  When the pressure in the brake lines increase from you hitting the pedal the piston in the caliper/wheel cylinder will move causing the stopping material to clamp either the rotor or drum creating fiction causing the car to slow down.  

What are all the parts of a braking system?

Master cylinder

·         The brake pedal is attached to the master cylinder.  The master cylinder is what forces the brake fluid through the system to each wheel

Power brake booster

·         The brake booster is a vacuum pump that increases the amount of force you can apply with your foot to the brake system

 ABS pump

 ·         The ABS pump is there to prevent the brakes from locking up under hard brakes.  How it works is if it detects a wheel sliding then it will automatically pulsate, causing the brakes to release and reapply.

 Calipers

 ·         Calipers are what hold the brake pads against the rotors on a disc brake system.  The caliper can have multiple pistons that when the brake is applied will squeeze the brake pads against the rotors creating fiction.

 Drum Brakes

 ·         Drum brakes are an older style of the brake system.  In a drum brake system, you have a wheel cylinder that will push the brake shoes out causing them to run against the inside of a brake drum.  Drum brakes used to be used on both the front and rear on cars but now you will only find them on the rears, and not all cars have drum brakes.  Some vehicles will have disc brake all the war around.

 ·         Disc brakes are cheaper to use and will usually last longer than disc brakes but are harder to replace and have to be adjusted periodically throughout there life

 How do I know when the brakes are getting worn out or there is a problem?

 There are multiple ways of knowing if there is a problem with the brakes.  Most brake pads have a wear sensor on them.  The wear sensor is a metal tab that will touch the brake rotor and make a squeaking noise when the brakes are getting thin.  Also as the brake pads get thinner, you will have more fluid in the calipers, so eventually the brake light will come on due to low fluid in the brake fluid reservoir.  

 Not all brake pads will have wear sensors on them so that you won't have that warning.  But brakes pads will make noise as they get thin anyway.  

 The best way to know when you will need your brakes replace is to check them checked on regular bases.  We would recommend having the wheels pulled, and brakes check on average every 20000 miles.  

 If you should have an issue with the ABS, then the ABS light will come on.  

 What does it mean if my brake pedals feel soft or goes to the floor?

 If the brake pedal feels soft or goes to the floor, then you will usually have one of three things wrong.  You can either have air in the brake lines, a leak somewhere or a bad master cylinder.  There are a couple of other things that could happen to cause a weak brake pedal, but those are the three most common.  

 What do I do if my brake pedal goes to the floor?

 Stop driving the car and have it towed to a shop.  You are in the process of losing your brakes, and the vehicle is not safe to drive.

 Whats all involved in replacing the brakes?

 That depends on whats needed.  A standard brake job involves replacing the brake pads or shoes along with the brake rotors/drums.

Why do you replace the rotors/drums? 

With use, the rotors and drums will get imperfections in the surface that can cause noise, vibration and affect stopping distance.  All manufacturers have a thickness spec that you don’t want the rotors or drums to get under.  If the rotors or drums get under the spec, they are more prone to warping, causing a vibration.  But they can also crack and come apart.  Most rotors/drums are made out a softer metal for noise and they get thin very fast.

 What’s all involved in doing a proper brake job?

 1.       Doing a proper brake job is a multi-step process.  

 2.       Inspect all components, make sure calipers and wheel cylinders are moving freely.  Make sure the caliper slides are moving freely.  Inspect all the rubber bushings to make sure none are torn.  On drum brake make sure the self-adjusted is working, and springs have proper tension.  

 3.       Check the thickness of rotors and drums to see if they can be machined or need to be replaced.

 4.       Clean and lube all moving hardware with a high temp ceramic grease

 5.       Clean all mounting surfaces.  

 6.       Replace any hardware that needs to be

 7.       Install new pads and rotors

 8.       Once everything is installed pump the brake pedal to ensure that everything is working properly.

 9.       On drum brakes, they will need to be adjusted to ensure they spin freely but don’t have too much play in them.

 10.   The last thing is to drive the vehicle to ensure the brakes are working and to also “burn in” the brakes sure they don’t make any noise.

 

 

 

 

 

Written by

Mason Shields

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