Owner's Problem Description
The vehicle owner reports that when applying the brakes, the brake pedal shakes, and initially, the steering wheel also shakes. This issue started after recent brake work was performed. The vehicle is otherwise in good condition, but the shaking has become a safety concern. The owner is unsure of the exact cause and seeks advice on possible solutions.
Professional Technical Analysis
The 2005 Mitsubishi Lancer is experiencing a noticeable shake in the brake pedal when brakes are applied, which is accompanied by initial steering wheel vibrations. This symptom often indicates potential issues with the brake components or installation errors. Possible contributing factors include warped brake rotors, improper installation, or debris between components. The vehicle's braking system should be assessed, with special attention to the rotor condition, lug nut torque, and the integrity of the brake pads. Inadequate torque can lead to uneven clamping forces, resulting in rotor warping, especially if power tools were used during installation. A thorough inspection of the brake system is essential, particularly after recent service, to ensure safety and performance. Components should be checked for proper alignment, and any debris or rust should be cleaned out to allow for proper contact. The shaking could also suggest that the new rotors are of inferior quality, potentially affecting performance and safety. Immediate attention is necessary to prevent further complications.
Possible Causes
Most common causes (ordered by frequency):
- Warped Brake Rotors: If the brake rotors were improperly installed or if they are of low quality, they may warp, causing vibrations when brakes are applied. This is particularly common if significant heat was generated during braking and the rotors were subsequently exposed to moisture, leading to thermal expansion issues. New rotors can also be defective, especially if sourced from unreliable suppliers. - Vibrations felt through the brake pedal and steering wheel, visible warping or scoring on the rotors, recent installation of aftermarket rotors.
- Improper Lug Nut Torque: If the lug nuts were not torqued to the manufacturer's specifications (typically 80 lb-ft for Lancer), it can cause uneven clamping forces on the rotor. This can lead to vibrations during braking, especially if power tools were used without a torque wrench, which can over-tighten the nuts and cause rotor warping. - Vibrations increasing with speed or brake application, potential lug nut markings or damage, no torque wrench used during installation.
- Debris Between Rotor and Hub: If there is debris, rust, or contaminants between the rotor and hub, it can prevent the rotor from sitting squarely against the hub, leading to vibrations during braking. This issue may not be immediately noticeable but can develop over time, especially after service work. - Visual inspection of rotor and hub surfaces showing rust or debris, vibrations during braking, especially after recent service.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Visual Inspection: Conduct a thorough visual inspection of the brake components, including rotors, pads, and calipers. Check for any visible signs of warping, uneven wear, or debris between the rotor and hub. Ensure that the installation was performed correctly.
- STEP 2 - Check Lug Nut Torque: Measure the torque of the lug nuts to ensure they meet the manufacturer's specifications (80 lb-ft). This can help identify if the nuts were over-tightened or improperly installed, which could lead to rotor warping.
- STEP 3 - Test Drive: Perform a controlled test drive to replicate the symptoms. Pay attention to vibrations felt through the brake pedal and steering wheel during braking. Document the conditions under which the vibrations occur, noting any correlation with speed or braking force.
- STEP 4 - Use Diagnostic Tools: If symptoms persist, consider using diagnostic tools such as a runout gauge to measure rotor runout and ensure they are within specifications. If rotors are found to be warped, plan for replacement with quality parts.
