1. Brake fluid: Check the brake fluid level in the master cylinder. If it's low, add brake fluid and check for leaks in the brake lines.
2. Brake pads: Check the brake pads for wear. If they're worn out, they can cause the brake pedal to push back.
3. Brake rotors: Check the brake rotors for warping or damage. Warped or damaged rotors can cause the brake pedal to push back and can also make a rumbling or clicking sound.
4. Brake calipers: Check the brake calipers to make sure they're functioning properly. Sticking or damaged brake calipers can cause the brake pedal to push back and can also make a rumbling or clicking sound.
5. Rear differential: If the rumbling/clicking sound is coming from the rear tire, it could be a problem with the rear differential. Check the differential fluid level and look for any signs of damage.
6. Wheel bearing: A worn-out wheel bearing can cause the brake pedal to push back and can also make a rumbling or clicking sound.
If you're not comfortable checking these things yourself, it's best to take your car to a qualified mechanic for diagnosis and repair.
