If you’re reading this, it probably means you’ve decided to replace your car’s brake pads on your own. Great choice!
However, all DIY projects will have a surprise or two. For example, getting halfway through replacing your brakes and suddenly realizing…
You don’t know how to release brake caliper pressure!
Well, don’t worry because we’ll walk you through every detail of releasing your brake caliper pressure, and how to avoid common mistakes.
In this guide, you’ll learn:
- Why you need to release brake caliper pressure
- What tools and equipment you’ll need
- Step by step procedure to release brake caliper pressure
Why Do You Need to Release Brake Caliper Pressure?
Brake calipers need their pressure released to make enough space for your brake pads to fit in the caliper and slide over the brake rotor.
But why isn’t there enough room by itself? Well, to understand that, we’ll have to know a little about how brake calipers work.
How Do Brake Calipers Work?
Brake calipers work by hydraulics. What that means is the entire brake system is sealed from pedal-to-pads, with hydraulic brake fluid inside.
When you press the brake pedal, it forces brake fluid to travel through hoses and tubes, and into the brake caliper. From there, the brake fluid pushes against the brake caliper pistons, forcing them to extend out and push against the backs of your brake pads, which pinch the brake rotors and slow you down.
To help understand exactly how brakes work, and why you need to release brake caliper pressure, check out this awesome video that shows exactly how it works!
So Why Release Brake Caliper Pressure?
Because brake pads wear down, which means they get noticeably thinner as you use your brakes.
Your brake caliper makes up for this lost material by letting the piston hang farther out of the caliper. This keeps your brake pads close enough to pinch the rotors, even as they get smaller and smaller from wear.
BUT, when you replace the old, worn pads with new, thicker brake pads, the caliper piston is much too close to the rotor.
That means, for your new, thick brake pads to fit over the rotor, you have to push the piston back into the caliper by releasing brake caliper pressure.
When is it a Good Idea To Release Brake Caliper Pressure?
The most common time you’d release brake caliper pressure is when replacing worn brake pads, like the example above. However, there are other situations when it comes up.
For example, I once removed a brake caliper to do other work, then forgot that it was not in place. When I pushed the pedal to test my brakes, the piston pushed fully out.
Because of this, I had to release the brake caliper pressure and put my brake pads back in place.
Similarly, another time you might release brake caliper pressure is if your caliper seizes up. Of course, you should replace a caliper ASAP if it seizes, but you can temporarily free it by releasing pressure and pushing the piston.
What Are The Benefits of Knowing How To Release Brake Caliper Pressure?
Unfortunately, maintenance can be pricey and must be done regularly. Brake pads are a wear item that you must have, and even though brake pads don’t cost an arm and a leg, your mechanic’s labor rates might.
Knowing how to release brake caliper pressure opens the door to do brake jobs yourself, which saves you from long wait times, expensive markups, and pricey labor costs.
Along with saving money, doing home maintenance makes you more confident in your car because you know that your brakes were replaced correctly. Also, mechanics can be wrong, and understanding the fundamentals of auto repair prevents you from falling victim to common misinformation.
What Should You Know About Releasing Brake Caliper Pressure?
Releasing brake caliper pressure isn’t difficult, but it’s a job that you want to be careful with. Brakes are sensitive, and a small mistake could have you towing your car to a dealership for repairs.
The most important thing to remember is that we don’t want air getting into the brake fluid. A common mistake to avoid will be leaving the bleeder screw open, or unscrewing the brake hose bolt.
If that happens then air will enter the system, and you’ll have to bleed all your brakes. Now, that’s not the end of the world so don’t be intimidated, but try to avoid it because that will be annoying.
Read More >> How to Use a Brake Bleeder Kit?
With that said, it’s not difficult to do correctly! Our step-by-step guide will detail exactly what to do, and how to avoid mistakes.
What Supplies Do You Need to Release Brake Caliper Pressure?
Releasing brake caliper pressure is pretty easy, and doesn’t require many tools. If you have a brake piston compressor tool, that’s great because it’s specifically made for the job.
However, if you don’t have a compressor tool, you can easily get the job done with a G-clamp, a large C-clamp, or channel locks. DO NOT use a screwdriver to move the piston. Using a screwdriver is a common mistake; not only is it ineffective, but it’s very dangerous if the screwdriver slips.
- Clear, plastic brake fluid hose
- Empty bottle
- Brake piston compressor tool (or a G or C clamp, or channel locks)
- Basic sockets and wrenches
- Car jack and jack stands
What Are The Different Methods to Release Brake Caliper Pressure?
The method you’ll use to release your brake caliper pressure will be based on whether you have a push-type caliper piston, or a screw-type caliper piston.
Push-Type Caliper Piston
This is the simpler version, and luckily it’s by far the most common. The method to release pressure is to open the bleeder screw, push the piston back into the caliper, then close the bleeder screw.
Because this type is so common, this is the method I will be outlining step-by-step below.
Screw-Type Caliper Piston
While this type is uncommon, it’s possible your car will have this style of caliper piston, so it’s important to know how to release its pressure.
The method to release pressure of this caliper is similar, but instead of pushing the piston back in, the piston has a screw-like thread and is designed to be rotated clockwise to screw back into the caliper.
However, to screw the piston back in, you’ll need a specific tool called a “caliper piston wind back tool.” The tool is simple to use: a pattern of pins will perfectly fit the holes on your screw-type caliper piston, then place a 3/8 inch ratchet into the cube and tighten it like any bolt or screw. You will see the piston slowly rotate back into its caliper.
You’ll know if your caliper uses this type of piston if there are multiple 1/8 inch holes on the piston face. If it does, you’ll want to purchase the wind back tool from your local auto parts store to properly release your brake caliper pressure.
How To Release Brake Caliper Pressure (5 Steps)
Step 1: Lift car and remove wheels
Jack the wheels comfortably off the ground, then place the vehicle securely on jack stands properly rated for your car. Consult your owner’s manual if you’re unsure of your car’s specified jacking points.
Remove the lug nuts holding your wheel on, then remove the wheel to expose the brake caliper.
Step 2: Remove caliper and brake pads
With your brakes exposed, remove the bolts holding your brake caliper on. There’s usually only two, and they face away from you. DO NOT remove the bolt holding your brake hose on, because that will leak brake fluid and let air in.
When you remove the bolts, the caliper should slide off without much force. Use a hanger to hold your caliper somewhere comfortable that won’t pull the brake hose.
Remove your brake pads from the caliper, but keep them handy. You should see a large ring inside the caliper – this is the piston that you’ll compress later.
Step 3: Prepare your tools
In this step, we’re going to get everything ready to compress the piston, because you don’t want to fumble for tools later on.
First, take one of your clear, plastic brake hoses and slide it over the brake caliper bleeder screw. Place the other end of the hose in a glass bottle or jar. This will catch any dirty brake fluid pushed out when the piston is compressed.
You may be tempted to skip the hose and bottle, but I highly recommend you don’t. Brake fluid is highly caustic, even a small amount can ruin paint, irritate skin, or poison animals and children.
Next, find the socket or wrench that fits your caliper bleeder screw. Don’t unscrew it yet, just keep the wrench handy.
Finally, take one of your old brake pads and place it back in the caliper, touching the piston. This is only used as a surface to push the piston, so there’s no need to position it perfectly.
Step 4: Compress the brake caliper piston
Now it’s time for the most important step: compressing the brake caliper piston!
If you’re using a compressor tool, follow your model’s instructions. If you’re using a G or C clamp, then place the fixed jaw on the backside of the caliper. Tighten the moveable jaw until it barely touches the brake pad covering the piston.
Now that everything is in position, take your wrench and loosen the caliper bleeder screw. Do not unscrew it completely, just barely loose is enough.
Keep the caliper positioned so the bleeder screw is facing up, that way air won’t enter the brake fluid.
Now, slowly tighten your compression tool – you should see the piston slide back inside the caliper, and brake fluid will flow into your bottle.
Once the piston has fully compressed, tighten the bleeder screw and remove the compressor tool. Place your new brake pads in the caliper and test that it fits over the brake rotor – there should be more than enough room now!
Step 5: Reassemble
You compressed the piston and made sure the brake pads fit, now it’s time to reassemble the brake caliper exactly the same as it came off.
First, assemble your new brake pads into the caliper, then position it and tighten the caliper bolts you removed. As a test, press the brake pedal to make sure it’s firm and there’s no air in the brake fluid.
Finally, reassemble your wheel and lug nuts, then remove your jack stands and lower your car to the ground. Test your brakes slowly, listening for any strange noises or vibrations.
My Final Thoughts on How to How To Release Brake Caliper Pressure
Releasing brake caliper pressure isn’t hard, anyone with basic tools and mechanical know-how can learn in a matter of minutes.
There are a few common mistakes to avoid, such as unscrewing the brake hose bolt, leaving the bleeder screw open, or using the wrong jack points when lifting the car.
However, with a little patience and caution, I’m confident you’ll get the job done no problem. By following the steps above, you’ll save money, expand your DIY knowledge, and have more confidence in your brakes.
Be on the lookout for more bargain DIY auto projects, and check back with MyCarCulture.com for all your how-to needs!