A brake caliper is a vital component of your vehicle’s braking system. It squeezes the brake pads against the surface of the brake rotor to slow down and stop your vehicle when you press the brake pedal. Over time, calipers can wear out or fail, reducing braking performance and creating potential safety issues. Knowing the signs of a bad or failing caliper can help you identify problems early and get your brakes repaired promptly.
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What Does a Caliper Do?
The caliper is the mechanism that squeezes the brake pads against the rotor when you apply the brakes. Inside each caliper are one or more pistons that are pushed outwards by brake fluid pressure when you step on the brake pedal. This clamps the brake pads against the rotor, creating friction that slows the rotor and wheel down.
Calipers also contain a bleeder valve used to remove air from the brake lines during maintenance bleeding procedures. And on some high-performance vehicles, the caliper houses extra fluid reservoirs to deal with the added demands of repeated hard braking.
Signs of a Bad Caliper
There are several symptoms that can indicate problems with a caliper:
Uneven Brake Pad Wear
A caliper not operating correctly can cause uneven wear on the brake pads. This is one of the most common signs of a sticking or seized caliper piston. You may notice one pad wearing down much faster than the other. Excessive uneven wear will quickly damage the thinner pad and rotor.
Pulling to One Side
Brake calipers use equal pressure to slow each wheel. If a caliper piston sticks, it can cause that wheel to drag and pull the vehicle to one side. This pulling sensation is especially noticeable under braking. Uneven braking effort from side to side makes the vehicle feel unstable and requires constant steering correction to stay straight.
Unusual Brake Pedal Feel
Problems with caliper piston retraction can also lead to changes in brake pedal feel. A sticky piston may cause the pedal to feel soft or spongy. You may need to press further to get the same slowing effect. The pedal may also feel firm as pressure builds up in one wheel circuit.
brake Fluid Leaks
The brake caliper houses rubber seals to hold pressure and fluid in the system. If these seals become cracked or damaged, you may notice drops of brake fluid collecting on your driveway or garage floor. Lower fluid levels can also cause the brake warning light to come on in the instrument cluster.
Excessive Heat
Dragging brakes generate a lot of heat. You may smell a burning odor after braking and find one wheel or caliper hot to the touch while the others remain cool. This localized overheating is a clue the caliper is not fully releasing.
Abnormal Noise
Sticking or frozen pistons can generate noise as you brake. This may sound like scraping, grinding or squealing coming from the affected wheel area. The noise happens as the uneven brake pressure causes vibration and friction between the pad, rotor and caliper.
What Causes Caliper Failure?
There are several root causes for calipers becoming stuck, seized or damaged:
- Corrosion – Rust buildup inside the caliper prevents smooth piston movement.
- Old age – Seals and bores wear over time allowing leaks and sticking.
- Debris – Small pebbles or other road debris get caught and jam the pistons.
- Overheating – Heat from heavy braking can distort piston bores.
- Hydraulic issues – A blocked brake hose or line, or poor bleeding, reduces pressure.
- Mechanical binding – Something is interfering with the caliper action.
- Manufacturing defect – Faulty seal materials or casting flaws.
How to Diagnose a Bad Caliper
If you suspect an issue with a brake caliper based on the above symptoms, here are some tips to help diagnose and confirm the problem:
Visual Inspection
Look around the outside of the caliper and brake assembly for signs of fluid leakage. Check brake pads for uneven wear. Look for corrosion, debris, cracks or damage. Note any discoloration from overheating.
Feel for Heat
After a test drive that includes steady braking, compare the temperature of all 4 brake rotors and calipers. Uneven heating points to a sticking piston.
Test Brake Pedal
Press the pedal firmly with the engine running and note any sponginess, increased effort or changes in pedal feel compared to normal. Release the pedal and check it returns to its rest position.
Detect Noise
Listen from outside the vehicle while an assistant presses the brake pedal. Note any scraping, grinding or squealing noises from the wheel areas.
Check for Dragging
Drive the vehicle in a straight line at low speed on a flat, dry surface. Let go of the steering wheel for a moment to see if the vehicle pulls to one side – a sign of dragging brakes.
Monitor Fluid Level
Look for the brake fluid reservoir to be lower than the “Max” mark. This could indicate a leak at the caliper. However, other brake system leaks can also lower fluid level.
Inspect Wheel Hub
If possible, remove the wheel and inspect the brake assembly. Look for brake fluid around the caliper or piston. Try moving the caliper piston with a clamp tool to check for binding or sticking.
How to Fix a Bad Caliper
Replacing faulty or damaged brake calipers is recommended for optimal safety and performance. Here are some repair options:
New OEM Caliper
For late model vehicles, installing a new OEM (original equipment manufacturer) caliper from your dealer or an online parts retailer typically gives the best results. New OEM calipers are dimensionally accurate and durable.
Remanufactured Caliper
As a lower cost alternative, you can purchase a professional remanufactured caliper. These are OEM calipers that have been completely disassembled, cleaned, and rebuilt with new seals, pistons, and bleed valves.
Refurbished Caliper
Some shops offer caliper refurbishing where they resurface the bores, replace seals, and clean internal corrosion. This can be effective at restoring function if the caliper body itself is still intact.
Brake Hose Replacement
Rubber brake hoses also deteriorate over time. It’s a good idea to replace the hoses along with bad calipers. Check for cracking, swelling or leaks.
DIY or Professional Repair?
Replacing brake calipers requires some mechanical skill. Here are some factors to help decide if DIY or professional repair is appropriate:
| DIY Considerations | Professional Repair Benefits |
|---|---|
| – Access to tools and jacks | – Specialized tools to remove tightly fixed bolts |
| – Familiar with brake bleeding procedure | – Skilled at proper brake bleeding to remove air |
| – Hand strength for stuck bolts | – Power tools make removal easier |
| – Know caliper orientation for reinstall | – Ensure correct reassembly and operation |
| – Manual specifies torque procedure | – Torque tools confirm proper tightening |
| – Ability to purchase required parts | – Can source and obtain all needed components |
| – Space and time for repairs | – Shop environment and time savings |
| – Confidence in dealing with seized parts | – Experience freeing stuck pistons and hardware |
| – Brake system knowledge | – Troubleshooting skills for other issues |
| – Accept costs of mistakes | – Warranty on work performed |
For most drivers without substantial mechanical experience, the use of professional brake technicians is recommended. They have the skills, tools, and experience to correctly diagnose problems and replace calipers efficiently.
Preventing Premature Caliper Failure
You can help minimize the chances of premature caliper problems through proper maintenance:
- Check brake fluid level regularly and change fluid per manufacturer schedule
- Lubricate caliper slides and pins with brake lubricant spray
- Inspect brake pads frequently and replace before they are fully worn
- Flush brake systems to remove moisture and debris
- Make sure wheels turn freely and don’t bind up
- Replace worn suspension components that affect wheel alignment
- Drive moderately and avoid excessive high speed braking when possible
Warning Signs to Address Quickly
While some caliper issues just lead to subtly degraded braking, other symptoms require immediate repair. Contact a professional right away if you experience:
- Pulling suddenly to one side when braking
- Brake pedal suddenly sinks to floor with no resistance
- Grinding noises or vibration when braking
- Visible leaking of brake fluid
Driving with badly compromised calipers can lead to brake failure or wheel lockup. Have your vehicle towed rather than risk using failing brakes.
Conclusion
Noticing the signs of stickiness, leaks, uneven pad wear, pulling, noise, or overheating can alert you to a potentially bad caliper. Typical causes include seal failure, piston sticking, debris ingress and system overheating. Replacing damaged calipers along with worn brake hoses will restore proper braking function. Consider having a professional perform caliper service given the importance of proper bleeding, torquing and system operation. With attentive driving and regular maintenance, you can maximize the lifespan of your vehicle’s calipers.