* Parking Brake (Emergency Brake) Cable: This is a common culprit. The cable might be sticking, frayed, or improperly adjusted, causing the rear brakes to remain partially engaged even when the parking brake isn't activated. Inspect the cable for damage and ensure it releases completely when the parking brake lever is disengaged.
* Rear Brake Caliper(s): A seized or sticking caliper piston is a very common reason for brake drag. This prevents the brake pads from fully retracting from the rotor, causing friction and heat. This can be due to corrosion, a damaged boot, or internal damage within the caliper itself. You'll likely feel heat emanating from the affected wheel(s).
* Brake Pads: While less likely to *cause* dragging on their own, severely worn or improperly installed brake pads *can* contribute to the problem, particularly if they're interfering with caliper movement.
* Wheel Cylinders (Drum Brakes, if applicable): If your F-150 has rear drum brakes (less common on '98 models but possible depending on trim), sticking wheel cylinders can cause the same dragging effect as sticking calipers. These need to be inspected and potentially replaced.
* Brake Lines and Hoses: Corrosion or damage to the brake lines or hoses can restrict fluid flow, leading to uneven pressure and potentially dragging brakes. Look for rust, bulges, or leaks.
* Master Cylinder: While less probable as a primary cause of *only* rear brake drag, a faulty master cylinder could contribute if it's malfunctioning and applying uneven pressure to the front and rear brake circuits.
* Proportioning Valve: This valve regulates the braking pressure between the front and rear wheels. A malfunctioning proportioning valve could send too much pressure to the rear brakes.
How to diagnose:
1. Feel for heat: After driving a short distance, carefully touch the rear wheels (be cautious – they'll be hot!). A significantly hotter wheel than the others points to a problem with that brake assembly.
2. Check the parking brake: Make absolutely sure the parking brake is fully released. If it still drags, something is preventing it from fully disengaging.
3. Inspect calipers/wheel cylinders visually: Look for signs of corrosion, leaks, or damage. Try to gently move the caliper pistons (with the brake system properly bled) to check for smooth movement. *Warning*: Do not attempt this unless you have experience working with brakes.
Important Note: Brake systems are safety-critical. If you're not comfortable diagnosing and repairing brake issues yourself, take your F-150 to a qualified mechanic immediately. Driving with dragging brakes is dangerous and can lead to brake failure, overheating, and potential accidents.
