Do You Need to Bleed Brakes When Changing Calipers?
Changing brake calipers is a common repair for worn out brakes. But do you really need to bleed the brake lines when installing new calipers? Let’s take a closer look at how calipers work, when to change them, and the best practices for bleeding brakes during a caliper replacement.
How Do Brake Calipers Work?
Brake calipers are a crucial part of your vehicle’s braking system. They are located at each wheel and their job is to apply the brake pads against the rotor when you press the brake pedal. Inside each caliper are hydraulic pistons connected to the brake fluid lines.
When you step on the brake pedal, it creates hydraulic pressure in the brake fluid system. This pressure gets transmitted through the lines to the pistons in each caliper. The increased hydraulic pressure pushes the caliper pistons out, squeezing the brake pads against the surface of the rotor.
The friction between the pads and the rotor is what slows down your wheels and vehicle. The caliper pistons apply smooth, even braking force at each wheel location based on how much pressure comes from the master cylinder when you press the pedal. This allows for balanced and efficient braking.
There are typically one or two pistons in each caliper depending on the brake type. As the brake pads wear down over time, the caliper pistons extend further out to maintain contact with the rotor. The caliper body also houses the brake fluid reservoir and bleeder valves used when bleeding the brakes to remove any trapped air bubbles. In summary, brake calipers transfer the force from your foot on the brake pedal into clamping force on the rotor to safely slow and stop your vehicle.
Do You Always Need to Bleed the Brakes?
Generally, it is highly recommended to bleed the brakes anytime you do a caliper replacement. Opening any part of the brake hydraulic system risks letting air in. Air degrades performance and safety.
However, in some limited cases you may be able to get away without bleeding:
- If you are extremely careful not to open any other brake lines
- When only working on rear brakes with a diagonal split system
- If you thoroughly bench bleed the new caliper first
But skipping a full brake bleed is often risky. The minimal time and effort of bleeding is worth ensuring air is fully removed for safe braking.
The Importance of Bleeding Brakes
Whenever the brake system is opened up, such as during a caliper replacement, air bubbles can enter the hydraulic lines. Air is compressible, while brake fluid is not. This means air bubbles will compress under pressure rather than transmitting braking force properly.
Symptoms of air in brake lines include:
- Spongy brake pedal
- Reduced braking power
- Brake pedal sinking to floor
To remove trapped air, a process called bleeding the brakes is needed. This flushes the old brake fluid and any air pockets out of the system.
Bleeding Procedures
Bleeding brakes can be done using a one-person or two-person method. A brake bleeder kit makes one-person bleeding easier. Here is the general process:
- Open bleeder valve on first caliper
- Pump brake pedal to push fluid/air from line
- Close bleeder valve
- Check master cylinder fluid and top off as needed
- Repeat process on the other three wheels
Having a helper pump the pedal allows fluid to flow more smoothly. Tap brakes intermittently to dislodge any clinging air bubbles.
Follow your vehicle repair manual for specific bleeding instructions. Adding fresh brake fluid is recommended for best results. Bleed in sequence from furthest caliper first working inward.
When Do Brake Calipers Need Replacing?
Brake calipers are durable, but eventually wear out and need replacing. Here are some signs your calipers may need to be changed:
- Brake fluid leakage: Damaged caliper seals or pistons can leak fluid
- Sticking pistons: Corrosion and wear cause pistons to stick and not retract fully
- Uneven pad wear: Worn caliper components cause one pad to wear faster
- Excessive play or looseness in the caliper bracket
- Unusual noises or vibration when braking
- Reduced braking power
Replacing deteriorated calipers ensures all your brakes continue clamping with equal force. Waiting too long can lead to brake failure.
DIY or Professional Replacement?
Replacing worn out brake calipers requires some mechanical skill and knowledge. You need to decide whether to do it yourself or seek professional service. There are pros and cons to each approach.
Doing a DIY brake caliper replacement means you need automotive know-how and the right tools. You must safely jack up the vehicle, disconnect the brake hoses without spilling fluid, bleed the brakes properly, and dispose of old fluid. Having a hydraulic jack, torque wrench, wrenches, brake bleeder kit, and repair manual is essential.
The benefit of DIY is saving on labor costs. But if you don’t have experience servicing brakes, are missing tools, or aren’t sure how to bleed the system correctly, then having a professional mechanic replace your calipers is advisable. This guarantees the job is done right the first time by someone qualified.
Professional caliper replacement at a shop does cost more for parts and labor. However, technicians have the expertise to efficiently swap calipers and bleed the brakes. They also have specialty tools that make the job easier. The peace of mind of professional service often outweighs the higher price for many drivers.
FAQs About Changing Calipers and Brake Bleeding
Here are answers to some frequently asked questions about replacing brake calipers and the necessity of brake bleeding:
How much does it cost to replace a brake caliper?
The parts cost is $100-300 per caliper. Add $150-250 in labor costs if getting professional service.
What tools do you need to change brake calipers?
Common tools include wrenches, hex keys, screwdrivers, pliers, torque wrench, brake bleeder kit, brake fluid, rags, eye protection.
Can you drive without bleeding brakes after changing a caliper?
It is unsafe and risky. Air trapped in the lines can greatly reduce braking ability, leading to brake failure and accidents. Always bleed after opening.
How long does it take to bleed brakes after a caliper change?
DIY bleeding takes 30-60 minutes. Professional shops can usually bleed all four brakes in 15-30 minutes.
What problems occur if calipers are not bled properly?
Spongy pedal, poor braking, uneven pad wear, brake noises, pulling, and complete brake failure can result from improper bleeding.
Can I just bench bleed new calipers instead?
Bench bleeding removes some air but does not ensure the entire system is bled. Doing a full bleed is strongly advised for safety.
The Takeaway
Replacing worn brake calipers is important for maintaining proper braking performance. Anytime the brake system is opened up, thorough bleeding is required to flush out air bubbles that can form in the hydraulic lines and degrade braking power.
While exceptions occasionally apply, bleeding all four brakes after a caliper replacement provides crucial safety and peace of mind. Don’t cut corners – take time to bleed brakes correctly when installing new calipers. Investing a little effort into bleeding can prevent much larger problems down the road.
