Brake Job for Fixed-Caliper Disc Brakes
November 5, 2015 I Jimmy Fallon
This is a write-up on how to perform a basic brake job (replace brake pads) on a fixed-caliper disc brake system. However, I really need to go over some brake basics first. If you already know about brake systems or just don’t care, skip ahead to the how-to directions.
There are two basic kind of brake systems: disk and drum brakes. Drum brakes are old, antiquated technology that is rarely put on new vehicles and if they are, they are only put on the rear. We will cover changing drum brakes thoroughly, but that will be a different article in the future. This write-up pertains to disk brakes. Typically, on a disk brake system a rotor is mounted to the hub via the wheel studs which spins along with the wheel and hub. A stationary caliper is mounted around this spinning rotor and is designed with pistons that will clamp onto the rotor using brake pads, which will eventually pull the vehicle to a stop. When you press on the brake pedal, brake fluid in the master cylinder is forced down the brake lines and extend the pistons, which apply the force on the brake pads.
As you probably expect, clinching a spinning metal rotor with ceramic/ metallic brake pads will cause a lot of heat and wear. That’s why brake pads are designed to be replaced. If you notice fading brake performance, vibrations when you brake or if it’s been over 10,000 miles since your last brake job, it’s probably time to take your wheel off and give it an inspection. Front brakes pads will require replacing much more often than the rears because vehicles are set up to brake harder on the front.
There are two types of disk brake systems: fixed and floating caliper. Floating caliper systems typically have a two-piece caliper (mount and piston body), have pistons on only one side of the caliper, and “float” along a pair of greased bolts since clamping pressure is only coming from one side. These are normally also more difficult to perform a brake job. A fixed caliper system has pistons on both sides, are open on the top of the caliper so the brake pads are visible and as the name suggests they are in a fixed position. We’re performing this brake job on our 2006 Hummer H3, which has a fixed rotor system. Again, we will be covering a floating system brake job in the future as they differ at several key points. Luckily for me, fixed-caliper brake systems are extremely easy to work on and require minimal tools. In fact, in an emergency I could perform this brake job with the vehicles jack & lug wrench and a Leatherman multi-tool.
First, a warning about heat. Brakes get extremely hot when you driving around even for a short time. Always let your car sit for at least an hour after driving before working on brakes. Once you have the vehicle jacked-up, secured and the wheels are off, you will need to inspect the brakes thoroughly. It’s a good idea to soak everything down thoroughly with brake cleaner because brake systems are extremely filthy.
The first thing you want to look for is brake pad thickness. A new brake pad is about 1/2” thick. You should never let your pads get less than 1/8” thick and it is recommended by most manufacturers that they get replaced when they are less than 1/4“.
Next, you’ll need inspect the rotor. Visually inspect it for warpage or grooves. It’s a good idea to take the back of your finger nail and drag it across the rotor. It’s common to feel grooves that are immediately visible to the eye. Warpage and grooving usually occur when the pads are worn at or below dangerous levels. If you detect either of these, it’s a good idea to go ahead and replace your rotor which is very easy to do during a standard brake job.
The last thing that you will need to look for is brake fluid seepage. Look specifically around the brake line and pistons. If you notice damp areas from brake fluid, you may want to consider changing or rebuilding your caliper. At a minimum, check to ensure that the banjo bolt that attached the brake line is tight.
What You’ll Need
1. Brake Cleaner
As mentioned before, hosing down your brakes is a good idea because these things are filthy.
2. New Brake Pads
You most likely already knew this. Do yourself a favor and don’t get the cheapest ones available because they will always squeal and wear out extremely fast. I like the Duralast Gold series which come with Lifetime Warranty from AutoZone.That’s right, if you ever wear them out (and you will), AutoZone will replace them for free.
3. Brake & Caliper Grease or Lubricant
4. Anti-Seize Compound
This is a good idea to use anytime you take a wheel on or off to avoid the lug nuts getting rusted on.
5. Caliper Compression Tool, Large C-Clamp, or Large Pair of Channel-Lock Style Pliers.
6. Needle Nose Pliers
These may not be necessary for every application, but they are for the Hummer H3.
7. Standard Socket Set
This was not necessary for the Hummer H3, but I know that it typically is for most applications.
8. Gloves and Haynes Manual
These are a good idea on most project.Gloves because brake parts are filthy (and sometimes very hot) and Haynes Manual because it always helps to have some extra help.
1. As mentioned before lift vehicle, secure vehicle and remove wheels.
2. Again, as mentioned before inspect brakes.
3. Using the needle nose pliers, remove the brake pad retainer pin clips. Ensure that you do not loose these or you will be buying a new hardware kit. If any of them are broken or badly bent, go ahead and buy that new hardware kit anyways. On some applications, the retainer pins are bolted in and the socket set will be required to remove them.
4. Remove the brake pad retainer pins. A little tapping or wiggling may be required to get them started.
5. Using the needle nose pliers, pull the brake pads straight out of the caliper from the top. Keep track of which side each pad came from.
6. At this point if your do not need to change your rotors, proceed to step 9. If you do need to change your rotors, unbolt the two mounting bolts. Make sure that you don’t unbolt the two caliper mating bolts because this will cause your caliper to split in half and will be a huge pain in the ass.
7. Once the caliper is unbolted hang it out of the way using zip-ties or a coat hanger. Do not let it dangle by the brake line because this will damage the brake line.
8. Pull the rotor off of the lug studs. A gentle tap might be necessary to get it started, but it should just slide off.
8. Install new rotor and re-mount the caliper.
9. Using the caliper compression tool, C-clamp, or large pliers, compress the calipers pistons to make sure that there is enough room for the new, larger brake pads. Depending on your brake system, this could cause brake fluid to be forced out of the top of your master cylinder. Watch for this and if it happens, make sure that you replace it at the end of the brake job.
10. Apply some Brake Caliper Grease to the backside of the new brake pads (make sure that you do not put it on the braking compound surface). Install the new brake pads by sliding them into the caliper. Compare the new pads to your old ones to ensure that they are put on the proper side of the caliper.
11. Reinstall the old Caliper Retaining Pin and clips.
12. Repeat on the other side of the vehicle. While you can replace the front brakes but not the back, never install brakes on just one side of the vehicle.
13. Apply anti-seize compound on the lug studs, re-attach the wheel and lower the vehicle.
14. Crank up the vehicle and before putting it in drive, pump the brake pedal a minimum of 12 times or until it feels firm. If you lost any brake fluid, replace it to the appropriate level.
LEGAL DISCLAIMER: We here at Dirty Shop Rags are experienced automotive veterans and many of us have worked professionally on vehicles. Hell, one of us is even ASE certified (it's a big deal). However, this article is meant to serve only as advice. We do not take any responsibility for you and your safety or any damage that might be caused to your vehicle. Please consult your local certified technician before attempting any work on your vehicle.
15. Now that you can stop safely, perform a burnout to celebrate your success. H3 Hummers can’t perform burnouts, so we decided to dress it up for a Halloween road trip and go hunt down some raptors.