If you’ve ever done your own brake repairs, you’ve likely run into an issue with not being able to fit the new brake pads into the caliper due to the piston being pushed out too far. This is a common problem that can be easily fixed by releasing the built up pressure in the brake caliper.
Releasing brake caliper pressure is a crucial step in any brake pad replacement job. In this detailed guide, we’ll walk through the entire process step-by-step, covering everything you need to know to successfully release brake pressure and install new brake pads.
Why You Need to Release Brake Caliper Pressure
Brake calipers use hydraulic pressure to clamp the brake pads against the rotor and slow your vehicle down. Inside each brake caliper are one or more pistons that push the brake pads into place when you press the brake pedal.
Over time, as the brake pads wear down, the caliper pistons gradually move farther out from the caliper to maintain contact with the thinner brake pads. This keeps your brakes working properly even as the pads wear.
When you go to replace worn out brake pads with fresh, new and thicker ones, the pistons are already pushed out too far to fit the new pads in. This is why you need to push the pistons back into the caliper housing to release the built up pressure before installing new pads.
If you try to force the new pads in without releasing the pressure, it can damage the caliper pistons and brake system. Releasing the brake caliper pressure ensures everything fits together smoothly.
When to Release Brake Caliper Pressure
The most common scenario when you’ll need to release brake caliper pressure is when replacing old, worn out brake pads.
However, there are a couple other instances where releasing pressure becomes necessary:
- If you remove the caliper for other work and accidentally press the brake pedal before it’s back in place, the piston will fully extend and get stuck. You’ll then need to release the pressure to retract it.
- If the caliper seizes up and sticks, releasing the built up pressure can sometimes free it up before needing to replace it. Try this as a temporary fix before replacing a seized caliper.
- When changing brake fluid or flushing the system, releasing pressure can help push out old contaminated fluid.
Anytime a caliper piston gets pushed out farther than it should be, releasing the pressure will bring it back to the proper position.
Benefits of Releasing Brake Caliper Pressure
Saving money is the number one benefit of learning how to release brake caliper pressure yourself. Mechanics charge expensive labor rates for brake jobs, so doing it yourself results in major cost savings.
You’ll also gain confidence working on your own vehicle brakes knowing they were done properly. Mechanics can make mistakes sometimes, so having the knowledge yourself prevents any issues.
Finally, you’ll be prepared to tackle this step yourself when it comes up in future brake repairs. Once you know how, it takes just a few minutes to release pressure and makes brake jobs much simpler.
What to Know Before Releasing Brake Caliper Pressure
Releasing brake caliper pressure is a straightforward process, but there are a few important things to keep in mind:
- Don’t let air enter the brake fluid – This can happen if you fully remove the brake hose bolt or leave the bleeder screw open. Air in the lines will require a full brake bleed.
- Use jack stands – Only work on brakes when the vehicle is lifted safely and secured on sturdy jack stands.
- Avoid using a screwdriver – Never use a screwdriver to try prying the piston back in, as it can easily slip and damage the piston.
- Catch brake fluid – Have a bottle ready to catch the brake fluid that will leak out when pushing the piston in. Dispose of used fluid properly.
- Check for rotor drag – Spin the rotor after compressing the piston to confirm the new pads aren’t dragging or binding.
As long as you avoid these common mistakes and exercise caution, releasing brake caliper pressure is a simple DIY job anyone can handle.
What Tools You’ll Need
Releasing brake caliper pressure doesn’t require many specialty tools. Here’s what you’ll need to have on hand:
- Floor jack & jack stands – To safely lift and support the vehicle
- Wheel lug wrench – For removing the wheel to access the brake caliper
- Brake piston compressor – Specialty tool made for the job, but clamps can also work
- Clear plastic tubing – Connects bleeder screw to a bottle to catch brake fluid
- Brake fluid catch bottle – An empty bottle to collect used fluid
- Bleeder screw wrench – Fits the caliper bleeder screw, usually 8 or 10mm
- Brake pad – Used as a pusher against the piston
- Basic hand tools – Socket set, wrenches, pliers, screwdrivers
Having these basic tools on hand will allow you to successfully release brake caliper pressure on most vehicles.
Methods for Releasing Brake Caliper Pressure
There are two different methods for releasing brake caliper pressure depending on what style of caliper piston your vehicle uses:
This is by far the most common style. The piston must be compressed back into the caliper body to release pressure.
Less common, but features threads that allow the piston to be screwed back in rather than pushed. Requires a special tool.
Below we’ll cover the step-by-step process for releasing pressure on the standard push-type brake caliper pistons. Check your vehicle repair manual if you have the less common screw-type.
Step-by-Step Guide to Release Brake Caliper Pressure
Now let’s go through the complete process from start to finish for safely releasing brake caliper pressure:
Step 1 – Lift and Support Vehicle
First, lift the vehicle using a floor jack on the proper jacking points and support it on jack stands rated for the weight. Refer to your owner’s manual for the jack points.
Chock the rear wheels if only lifting the front. Remove the front wheels to access the brake calipers.
Step 2 – Remove Caliper and Pads
Locate the two caliper bolts that hold it to the brake assembly. Remove these bolts using the appropriate socket or wrench and set them aside.
Carefully slide off the caliper and hang it up using a wire hook. Take care not to overextend the brake hose.
Remove the old brake pads from the caliper assembly. This will expose the brake caliper piston.
Step 3 – Prepare Tools
First, attach clear plastic tubing to the bleeder screw and place the free end in a bottle to catch brake fluid.
Get the bleeder screw wrench ready, but don’t open it yet. Only crack it open slightly in the next steps.
Take one old brake pad and place it back into the caliper to use as a pusher against the piston.
Step 4 – Compress Piston
If using a brake piston compressor tool, follow the manufacturer instructions for use.
For a DIY approach, use a C-clamp or large pliers on the back side of the caliper. Position it to push directly against the brake pad on top of the piston.
Slightly crack open the bleeder screw (don’t remove fully). This allows fluid and pressure to escape when compressing the piston.
Slowly tighten the C-clamp, compressor, or pliers to push the piston into the caliper. Take your time and periodically check progress.
Once fully seated, tighten the bleeder screw back up to close it off.
Step 5 – Reassemble Caliper
Place your new brake pads into the caliper and slide it back over the rotor. Spin the rotor to confirm the new pads are not dragging or binding against it.
Reinstall the caliper bolts and torque them to spec using a torque wrench. Double check that the brake hose is not twisted.
Press the brake pedal firmly to restore proper pressure through the system. Ensure the pedal feels firm, not spongy.
Reinstall wheels, lower vehicle, and take it for a test drive. Check for any noises or pulling when braking.
And that’s it! By following these steps you can successfully release brake caliper pressure at home using common tools. Just take your time and be cautious to avoid any mistakes.
Here are some answers to common troubleshooting questions that arise when releasing brake caliper pressure:
Brake pedal still spongy after bleeding?
Air may still be trapped somewhere in the system. Double check all bleeder screws are tight and retry bleeding each wheel cylinder one at a time.
Caliper piston won’t compress fully?
Dust seal may be damaged. Carefully pry it back and reposition with a pick. Replace seal if torn. Pistons can also seize up over time.
Brake fluid leak after releasing pressure?
Damaged caliper piston seal. The piston seal will need to be replaced to stop the leak. Have system inspected for further damage.
Brakes feel uneven after service?
Air trapped on one side, incorrectly seated pads, or a stuck slide pin. Re-bleed that corner and lubricate slide pins. If issue persists, inspect calipers.
Brake pedal pulsates when stopping?
Indicates a warped brake rotor. Resurface or replace rotor to correct pulsation issue. Always machine rotors when replacing pads.
Preventing Future Caliper Pressure Buildup
To help avoid having to regularly release brake caliper pressure, here are some tips:
- Lubricate caliper slide pins – Stuck pins can prevent the caliper housing from retracting properly as the pads wear down.
- Replace seals when servicing – Worn dust and piston seals will allow pressure to build up prematurely.
- Don’t postpone brake service – Letting pads wear down too far results in over-extended pistons.
- Machine or replace rotors – Warped rotors push pads out unevenly contributing to pressure.
- Flush brake fluid regularly – Moisture-contaminated fluid boils and causes pressure spikes.
By staying on top of brake maintenance and lubrication, you can minimize how often you need to release brake caliper pressure down the road.
Is Releasing Brake Caliper Pressure Difficult?
While it may sound complicated if you’ve never done it before, releasing brake caliper pressure is actually a very simple process that anyone can master.
The basic steps are straightforward and do not require advanced mechanical skills. Having the right tools and taking your time is the key.
As long as you avoid the common mistakes outlined above, there should be no issues safely releasing pressure and fitting new pads. Just work slowly and double check everything.
The most important things to remember are:
- Don’t let air or contaminants enter the brake fluid
- Always use jack stands and chock tires
- Catch any expelled brake fluid so it doesn’t make a mess
- Do not force anything – if the piston won’t compress, determine why first
Take the proper precautions and safety steps, and you’ll find that releasing brake caliper pressure is easy. With a little practice, you’ll get faster each time you need to do it.
Now that you know how to successfully release brake caliper pressure, you can take on brake pad replacements confidently yourself and save significantly on labor costs.
While not an absolute beginner DIY job, releasing pressure is very doable for anyone with some mechanical ability and the right tools.
Just remember to work slowly and carefully to avoid any mistakes. Following the step-by-step guide above will set you up for smooth brake jobs.
Here’s a quick recap of the key points:
- New pads won’t fit without releasing built-up caliper pressure
- Use jacks and jack stands safely before working on brakes
- Push pistons back in using a clamping tool or C-clamp
- Open bleeder screw so pressure releases as you compress
- Refit caliper and pads correctly when done
- Avoid damage by using patience and care
Doing your own brakes is one the most rewarding DIY jobs. We hope this guide gave you the knowledge needed to master this crucial step and become more auto repair self-sufficient.
Let us know in the comments if you have any other brake service tips or tricks!