Overview: Drum Brakes System Diagnosis

does your vehicle not stop as quickly as it used to are you hearing noise while driving or breaking do you feel vibration in the pedal or steering wheel when you slow down does your car pull to one side when driving and even more when breaking these are all signs that you may be having problems with your brake system this system consists of many components that need to be inspected to ensure optimal braking performance and vehicle safety in this video we'll look at the components of the drum brake system and how to diagnose issues you may find will begin examining the system inside the vehicle by checking the brake pedal and dashboard lights start the vehicle and press the brake pedal if the pedal seems mushy it might be due to having a brake fluid leak or it could be that the brake fluid needs to be changed as its absorb too much more sure over time and illuminated brake light AB S. light or check engine light can also alert you to problems with the brake system now let's cut off the engine and pop the hood to visually inspect the master cylinder for signs of leaking fluid moisture around fittings or low fluid in the reservoir often indicates a leak in the system if it's not full add fluid consult your owner's manual to determine the correct type of brake fluid to add look at the fluid condition in the reservoir if it's cloudy or dark it needs replacing many vehicle manufacturers recommend changing brake fluid every twenty four months or twenty four thousand miles as brake fluid will absorb moisture from the air over time which can cause corrosion and greatly reduced braking performance okay now that we've completed some basic troubleshooting let's take a look at the drum brake system since we'll be working under the car it's important to observe basic safety precautions wear a dust mask and I protection to protect yourself from brake dust do not use compressed air to claim brake parts always use a spring break cleaner to keep brake dust from becoming airborne parked the vehicle on a flat dry surface shocked the wheels and make sure the parking brake is not engaged if the brake shoes being inspected are on the rear of the vehicle engaging the parking brake will lock the brake shoes into the brake drum and prevent the drum from being removed automatic transmissions in park and manual transmissions in neutral when Jack in the vehicle insured the Jack is rated for the weight of the vehicle being lifted and use factory live points which can be found in your owner's manual once the vehicle is lifted support the vehicle on Jack stands and not the Jack next we'll check the primary components of a drum brake system when the brake pedal is pressed fluid is forced through the brake lines to the wheel cylinder that presses the brake shoes into the drum using small pistons when the brake pedal is released the wheel cylinder pistons retract and return springs for the shoe away from the drum over time or under extreme use the return springs loose tension strength and don't properly retracted shoes away from the drum this is known as break drag which can cause excessive wear and unnecessary he build the resulting in glace brake shoes a condition that can cause breaks to make a squealing or grinding noise these noises can also be an indication of brake shoes that are worn down and need to be replaced now check the braking surface of the drum for discoloration caused by excessive heat or cracks if this condition exists the drum must be replaced check to see if an outer lip has formed or if there are groups present if either of these conditions exist the drum must be resurfaced or replaced even if the friction surface looks moved there can be minor peaks or valleys that could cause a new shoes to ride on high spots instead of contacting the full face of the drum which will result in decreased breaking next check the thickness of the drum with a break from micrometer to make sure it is above the minimum thickness requirement minimum thickness specifications are stamped into the drum usually near the mounting hub your local AutoZone store can help check the thickness of your drum if the drum has worn down below this thickness it's time to be replaced for best braking performance always resurface or replace drums when replacing brake shoes closely examined the wheel cylinder for signs of leakage leaking brake fluid will contaminate the brake shoe lining causing drum brakes to grab and make more noise this is a brake drum off of a vehicle to make it easier for you to see next take a look at your whole down springs when these have been weakened by heat they can cause the brake shoes to vibrate and rattle it the springs become too loose or break they can cause more serious problems like damaging the brake drum or possibly even because the brake system to lock up since weakness from heat and age can be visually determined it's a good practice to replace all springs and hold down hardware whenever you replace the brake shoes this is your self adjusting mechanism it insures your shoes keep their proper position in relation to the drums over the life of your breaks your paddle wheel usually travel closer to the floor when brake shoes are out of adjustment it be adjusting cables levers and springs are worn rusted or weakened by heat they can't keep her drums properly adjusted to maintain the correct shoe to drum clearance resulting in delayed and or reduced braking effort take time to inspect all hoses for cracking chafing swelling or leaking also check all steel lines for leaks Kinks corrosion or damage a brake drum system is complex but still simple enough for you to troubleshoot more information on how to replace brake shoes see our video how to replace drum brakes or stop by your local AutoZone for everything you need to do the job right including expert advice parts are just part of what we do get in the zone and thanks for watching