Any issue related to your vehicle’s braking system is no joke. Your brakes are one of the most important safety features of your vehicle, and ensuring that everything is working as it should is extremely crucial.
One of the problems you might encounter (no matter how well you keep up with maintenance) is a brake caliper piston that won’t compress, which can happen for several reasons.
Reasons Why Your Brake Caliper Won’t Compress
Dealing with a brake caliper that won’t compress can be quite troublesome. It’s the one thing that drivers hope will never happen to them, especially when driving fast on a freeway.
So why exactly does this happen?
Corrosion
Corrosion is the most probable reason why a brake caliper will fail to compress. Brake calipers are made out of metal, which can accumulate rust over time.
Piston Cracks
Brake pistons that have phenolic resin can crack after a while.
Improper Installation
Brake pistons that weren’t installed properly are more prone to premature wear and seizing.
Excess Brake Fluid
Bleeding the brakes without replacing the worn-out brake pads and resetting the pistons can fill the brake system with brake fluid, preventing the brake caliper pistons from compressing.
How to Compress a Brake Caliper (With and Without Piston Tools)
Brake caliper pistons can be compressed in several ways. While using compression tools like a C-clamp or channel lock is the easiest way to do the job, you can get around the task without it.
Before anything else, make sure that you’re wearing gloves and other safety equipment to prevent any injuries.
Proceed with loosening the wheel bolts or nuts and raising the vehicle using jack stands.
Next, remove the wheel and unbolt the rear caliper. Make sure the caliper isn’t hanging freely to avoid damaging the brake lines.
Once that’s out of the way, you can open the cap on the brake fluid reservoir.
Compress a Brake Caliper Using Tools
When using a brake caliper wind back tool, choose a circular plate that interfaces with the caliper’s piston. The plate should have two pins or notches that can fit into the grooved piston.
The next step is to grab the back plate to create some resistance to push the piston back into the caliper.
Attach the plate to the wind back tool and adjust it accordingly. Turn the rear lever and tighten the bolt to hold the plate back in place.
Keep turning the rear lever until the piston spins and moves back. Eventually, the piston should go all the way in until there’s enough space for the new brake pads.
Finally, loosen the lever and rear bolt and remove the unit from the caliper.
Other Ways to Compress a Brake Caliper
One downside to using a wind back tool is that it’s accompanied by a kit purchased separately. If you don’t want to buy all the necessary hardware, here are some ways to push back the brake caliper piston.
Using an Old Brake Pad
Before throwing out your used brake pads, you might want to keep them around for a little bit more. An old brake pad can be used to compress a brake caliper piston.
Using a piece of wood or a flat metal object, apply even pressure against the old brake pad. Keep pushing the wood or metal object directly against the piston until it compresses against the caliper.
Using a Screwdriver
Use a large flathead screwdriver or a pry bar and wedge it between the caliper and piston. Pry the piston back into the caliper, but be careful not to damage the piston or caliper.
Brake Caliper Designs
There are generally three types of brake caliper designs一fixed, floating, and sliding.
Fixed Brake Caliper
A fixed brake caliper is mounted to the suspension, hence its name. This type uses two, four, or six pistons to apply the brake pads.
One advantage a fixed brake caliper has over other designs is its size and weight. A large and heavy caliper like this is great at absorbing and dissipating great amounts of heat and lets the rotor and pads run cooler.
However, a fixed brake caliper has multiple pistons and split bodies, which means servicing one can be quite complicated.
Floating Brake Caliper
A floating caliper design isn’t mounted to the suspension. For this design, the caliper can move within a limited range on an anchor plate that’s mounted to the suspension.
Compared to a fixed caliper, a floating brake caliper has a simpler construction, lower cost, and compact size. However, the flexibility of a floating caliper can contribute to a spongy brake pedal.
The flex also causes the caliper body to twist slightly when the brakes are applied, resulting in tapered wear of the brake pad lining material.
Sliding Brake Caliper
The body of a sliding brake caliper is directly mounted to the anchor plate. Instead of using pins and bushings, a sliding caliper moves on ways cast and is machined into the caliper and anchor plate.
A sliding caliper has the same advantages and disadvantages as a floating caliper.
Brake Caliper Maintenance
Maintaining and cleaning your brake calipers are key if you want to reduce the risk of your caliper pistons getting stuck.
Cleaning the brake caliper can also extend its lifespan and maximize your vehicle’s braking efficiency.
When cleaning your brake calipers, make sure to use a cleaner that’s intended for brake parts. This will help break down the dust and grime without damaging the hardware.
Once you’re done cleaning and wiping the brake caliper dry, it’s also a good idea to apply a protective coating or caliper paint. This enhances the caliper’s appearance and forms a layer that protects it from dirt and grime.
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Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.
