1. Bleeding the Brakes: This is the most likely solution. Air in the brake lines prevents the system from building proper pressure, resulting in a spongy or squishy pedal. You'll need a brake bleeder kit (usually available at auto parts stores). The process involves opening the bleeder valve on each caliper while an assistant pumps the brake pedal. This forces the air out of the lines. Important Considerations:
* Order: Bleed the furthest caliper from the master cylinder first (usually the rear passenger side, then driver's side). This pushes air out systematically.
* Proper Technique: The assistant should pump the pedal firmly several times, then hold it down while you open the bleeder valve. Close the valve before the assistant releases the pedal. Repeat this process until clear brake fluid comes out without bubbles.
* Fluid Level: Keep the master cylinder reservoir topped off with the correct brake fluid for your vehicle. Never let it run dry.
* Type of Fluid: Use the correct type of brake fluid specified in your owner's manual. Mixing different types can cause problems.
* Cleanliness: Keep the bleeder valve and surrounding area clean to prevent contamination of the brake fluid.
2. Master Cylinder Issues (Less Likely, but Possible):
* Low Fluid: Check the master cylinder fluid level. If it's low, you may have a leak somewhere in the system (possibly a damaged seal or hose). Addressing the leak is crucial before bleeding.
* Master Cylinder Failure: In rare cases, a faulty master cylinder could cause a spongy pedal. This requires replacement.
3. Caliper Issues (Less Likely, but Possible):
* Improper Caliper Installation: If the calipers weren't installed correctly, they might not be sealing properly, leading to a spongy feel. Double-check your work to ensure they are correctly mounted and the pistons are properly seated.
* Internal Caliper Problems: A damaged caliper seal could also be the culprit. If you've already bled the brakes and the problem persists, inspect the calipers for any leaks.
4. Brake Lines (Least Likely):
* Leaking or Damaged Lines: Examine the brake lines for any damage, leaks, or kinks. Replace any damaged lines.
If you're uncomfortable performing these repairs yourself, take your vehicle to a qualified mechanic. Brake system failure is dangerous, and improper repair could lead to accidents. The cost of a professional repair is far less than the cost of an accident. Start with bleeding the brakes – that's the most common cause of a squishy pedal after brake work. If that doesn't solve the problem, further diagnosis is needed.
