How To Replace Brakes

How to replace brakes is not something to be taken lightly.  Most DIY mechanics and home mechanics are capable of completing the task without any issues, but there are a few things anyone attempting to do this repair should know.  This article is a bit lengthy, but it explains the reality of what to expect.

What You Need to Know About Brakes

The first thing to do is determine what is going on with the brake system that makes a driver feel it needs attention.   This article does not address that question, however, I have written an article on the website for my shop that covers the subject.  It is available HERE:

What You Need to Know About Brakes

The focus in this article is replacing the brake pads & rotors on a disc brake system.  When replacing brake pads it is important to either replace the brake rotors or have them resurfaced to prevent brake pull, brake shudder or pulsation, and brake squeal.  Brake pad/rotor kits are available at a very reasonable price that makes the option of resurfacing brake rotors a hassle.

Getting Parts

Resurfacing brake rotors assures that the contact surface of for the new pads is straight and smooth, just as a new rotor is.  The problem with resurfacing rotors is #1-the time for the machine shop to complete the operation, #2-getting the rotors to the machine shop, and #3-rotors can tend to warp easier after material is removed.  I find it much quicker and less chance of issues to replace them.  The cost is a few dollars more, but time savings and new vs refaced is good peace of mind.

Brake Pad and Rotor Kits

Amazon can supply Brake Pad and Rotor Kits for your vehicle, and offer many options if you are interested in performance parts.  Just add the vehicle you are working on to “Your Garage” at Amazon to assure you are getting the proper application.

Tools You Will Need to Replace Brakes

Tools needed to replace the brake pads & rotors will vary somewhat with different vehicles.  You can find the specific tools needed at Mitchel DIY  Online Auto Repair Manuals – Mitchell 1 DIY  

Online Auto Repair Information for the Do-it-Yourselfer

This article covers tools needed for most applications.  The tools and equipment are discussed with the DIY or home mechanic in mind, and may not be suitable at a professional level where constant use on a daily basis is required.  Professional tools can drive the price up to where it is more cost effective to have a professional do the repairs and this article is intended for the DIY mechanic or home mechanic.

Having the tools and equipment ready before you start saves a lot of time and frustration.  These tools include a jack and jack stands.

Jack and Stands

You can use a scissor jack that comes with most cars, but a hydraulic floor jack will make life much easier, and SAFER.  Jack stands are a MUST for safety.  NEVER work on or especially under a vehicle that is not properly supported.

Hand Tools

You will need a lug wrench, socket set, screwdrivers, C-clamp or piston tool, hammer, and a wire brush, and some penetrant oil.

You can use the lug wrench that comes with your car or for a faster option of a 4-way lug wrench.

A socket set is needed to remove the calipers and mounting bracket.  Some vehicles use allen head bolts for calipers.

The tools you choose will depend on how much DIY you are planning to do.  Keep in mind if you are going to be doing other projects in the future, plan your tool purchase accordingly.  As I said, you may or may not need allen sockets, and you may need metric OR  SAE.  If you don’t know you can consult  Mitchell Online Auto Repair Manuals 

You will need a screwdriver to release the pressure from the brake pads for caliper removal.  If you don’t already have a screwdriver for this purpose, get a set that has at least one fairly strong slotted screwdriver for prying.

A hammer is usually needed to break the rotor loose from the hub.  While a hammer is a fairly common item to have on hand, if you need to purchase a hammer, a dead blow hammer is a great choice.

The piston will need to be pushed back into the caliper.  A C-clamp or piston tool is needed to perform this task.  If you don’t have a large C-Clamp, the tool designed for this operation is actually more affordable.

Lastly, you will likely find the rotor has rust & corrosion where it attaches to the hub.  Penatrant will be needed to loosen that.

Torque Wrench

Torque wrenches vary in price and function so greatly that I will refer you to a previous article that covers this topic.  You can find it HERE.  

Getting the Job Done

Now let’s take a look at how to replace brakes on a typical disc brake vehicle.  Start by loosening the lug  nuts slightly using the lug wrench.

Support the Vehicle

Use the jack to raise the front (or rear if you are doing rear brakes,) of the car so the wheel are off the ground.  Before going any further SUPPORT the vehicle with a stable set of jack stands.  When the vehicle is solidly supported with the tires off the ground, spin the wheels.  Do this to make certain that there isn’t a caliper dragging or locking up a wheel from turning.  There should be some drag, but you should be able to turn the wheel without excessive effort.  Remove the wheels.  At this point, it is a good idea to spray penetrant around the center of the rotor where it fits over the hub. This is to help with removal as you progress through these steps.

Remove the Calipers

With the wheels off, the next step is to remove the calipers.  It will be easier to do this if the steering wheel is not locked.  Using both hands, one at the front of the brake rotor/disc and one at the rear, turn the rotor so the caliper is away from the suspension components.  Using a strong screwdriver, you can usually apply pressure on the caliper to remove the pressure from the pads. Doing this will  make caliper removal much easier.  You can do this through the opening on the edge of the caliper that is perpendicular to the rotor.  Reach through the opening and engage the screwdriver against the back side of the rotor.  Apply pressure to the screwdriver moving the caliper away from the back of the rotor.

After releasing the pressure from the pads, remove the caliper from the caliper hanger.  There will be two bolts attaching the caliper to the hanger.  These bolts may be hex head or allen head.  In some cases you may even find torx head bolts here.  Remove the bolts.  I find it works best to remove the top bolt first on the passenger side of the vehicle, and the bottom bolt first on the driver’s side.  This will keep the caliper from moving while removing the bolts.

Support The Caliper

After the bolts are removed, work the caliper away from the rotor.  Support the caliper by hanging it from a suspension component with a bungee cord.  DO NOT let the caliper hang by the brake hydraulic hose.

Push the Piston Back Into the Caliper

The brake pads may come off with the caliper, or they may be held in the caliper bracket and stay on the vehicle.  If the pads come off with the caliper, remove them and set them aside.  It is a good idea to isolate the drivers side pads from the passenger side pads.  Setting them aside will aid identification during re-assembly.

Push the piston back into the caliper using a C-Clamp or the tool  described above along with a small block of wood.  Place the small block of wood between the clamp, or tool, and the piston to prevent damage to the piston.  Clean any dirt, rust or corrosion from the areas where the caliper has contact with the hanger.  Carefully inspect the caliper and the hydraulic lines for any indication of fluid leakage.  If there is any indication of a leak, it MUST BE REPAIRED BEFORE PROCEEDING!

Remove the Caliper Hanger

Most vehicles will require the caliper hanger to be removed before removing the rotor.  There will be two bolts holding the caliper hanger to the steering knuckle.  Remove the bolts, remove the hanger and set aside.

Remove the Rotor

The rotor should be removable at this point.  Check to be sure there is not a bolt going through the face of the rotor into the hub, if so, remove it now.   Things can get interesting at this point, ideally the rotor would slide off the hub now. Rarely is that the case.  Rotors are usually pretty stubborn about coming off and will require some persuasion.

If you find that to be the case, start by using a hammer to “shock” the rotor into moving.  Hit the flat surface around the lug studs first to try to break it loose.  Be very cautious about hitting the lug stud as that will create another repair.

If the rotor does not move, and you are replacing the rotor, then use the hammer on the shiny surface of the rotor, working your way around as you try to shock it loose.  No success here will require hitting on the back side of the rotor.  If you do that, loosely place a lug nut on one or two studs so in the event that it suddenly breaks loose, the rotor doesn’t go flying across the shop.

Persistence

In some cases, a rotor can attempt to show you who is boss and still not want to break loose.  It is now time to think outside the proverbial box.  Using a long bolt, nut and a couple of washers to fashion a press of sorts is the “strong persuader” here.   The bolt must be smaller in diameter than the caliper mounting bolts and long enough to reach the back side of the rotor plus an inch or so.  You may need to re-install the caliper holder to do this, and you may want to use two bolts to distribute the pressure.

Put the bolt through the caliper  bolt hole, install a washer on the rotor side of the caliper bracket, then install a nut on the bolt.  Hold the nut with a wrench and turn the bolt through the nut which will apply pressure on the back side of the rotor.  The pressure will break the rotor loose from the hub as you apply more pressure.  Again, using two bolts will be more persuasive than 1 bolt.

Clean Up

By now, you should have all the components apart and be preparing for re-assembly.  Using a wire brush on a drill (or a hand held wire brush if no drill is available,) clean the surface of the hub around the lug studs.  Clean the caliper hanger surfaces where caliper or brake pads contact.  Also clean the areas that the brake pad hardware contacts.   Make sure the caliper guide pins, which sometime are the bolts, allow the caliper to move freely on the guides. Occasionally the guides  become seized and will require further disassembly to clean.

Re-assemle

Place the rotor on the hub, if a face screw was removed, re-install the screw.

Pads that mount in the caliper hanger will  have some hardware to place on the hanger before the pads are installed.  Install the hardware, then install the pads on the hanger.  When installing the pads, look for the wear sensor tabs and notice the shape of each pad.  You will need to assemble the pads in the same maner as they were originally.  Not all vehicles have inboard and outboard pads that are shaped the same.  Look at the pads you removed to identify which pad goes where.  You can generally identify the inboard pad by marking from the caliper piston.  Be certain that the wear sensor is on the same end of the pad that you removed.  These will vary from side to side.

Place the caliper hanger in position and tighten the bolts to specification.  Install the caliper and tighten the bolts to specification.  Put the wheel back on and install the lug nuts snugly.

Lower the Vehicle

Using the jack, raise the vehicle and remove the jack stands.  Lower the vehicle and tighten the lug nuts to specification.  Lug nut torque is very important to ensure the wheel is tightened evenly.  This is critical with aluminum wheels, it will prevent lug nuts from loosening and causing a wheel to come off.  Equally important, proper torque of lug nuts will prevent your new rotors from warping.  Use a torque wrench to properly tighten the lug nuts.

Important Last Step

Before moving the vehicle, pump up the brakes.  The caliper pistons will need to travel to engage the pads to the rotors.  It  will take a few times operating the brake pedal to accomplish that.  If you don’t do this, your vehicle will not stop the first time the brakes are applied.

Test drive the vehicle to verify proper operation.  If something doesn’t feel right, find outwhat is going on before operating the vehicle.

 

Next article:  ENGINE HOIST RECOMMENDATIONS

Previous Article:  CHOOSING A TORQUE WRENCH

 

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