Brake gurgle at slow stop

Question

A gurgling groaning noise from the front left hand side during the final few yards pulling up to a red light. This only happens when the brakes are hot for example after driving down a hill. The car is healthy and had no probs prior to replacing front pads and rotors, bleeding in new fluid & bedding the pads. To see if the rotors were the issue I switched pads & rotors together between front right & left, bled again but the noise still happens and is definitely from the front left.

After research thought this question was the answer which was caused by the rotors & pads although with my car the issue is just one side and didn't follow with the pads & rotors as they were switched left and right. There are no fluid leaks or issues braking aside the very disconcerting noise so I'm wondering if the front left brake hose could be contributing - or some other issue on this 2008 Subaru Legacy.

EDIT: from comments. The pistons & slider pins move well. Each calliper has two pistons, dust boots intact. The noise is linked to the brake pedal & only happens whilst stopping on hot brakes at very low speed after changing out the parts described above.

EDIT: There is no vibration through the car, just the strange noise on hot rotors which may also be known as creep growl or creep groan.

Answer 1

Check the ABS sensor for that wheel to see if there is a buildup of magnetic dust on the face of the sensor near the tone ring. (A small inspection mirror helps.) If there is, blow the sensor clean with compressed air.

A buildup of magnetic dust there will weaken the signal that's sent to the ABS computer. Combine that with the natural weakening of the signal at low speeds, and the computer can think the wheel is locked up. That would cause an ABS activation, which you may hear as a groaning gurgling noise.

This happens on my car. I live in the rust belt, so I have to clean my ABS sensors every few months.

Answer 2

To close out this question I replaced the previous cheap pads & rotors with better quality parts. We then carefully bedded in the new pads and the gurgling noise has gone. It was uncanny how fluid or liquid like the problem sounded as the old pads slipped on the rotors before the new parts were fitted.

Answer 3

Process of elimination: pads and rotors confirm good by switching sides. Checking the heat on each side seems to indicate calipers and hoses are ok, but be sure to make sure all pins and brake clips are not binding up the pad movement. Clean and lubricate them. Might as well replace both brake hoses as they are due. After you are sure all the brake components are good, move to suspension. Thoroughly check ball joints and inner and outer tie rod ends. Check for worn bushings on control arms. Any of these components can cause vibrations while braking. Especially make a thorough check on the wheel bearings. Sometimes they can be bad even when you can't feel any play by rocking the wheel. You may need to check it with a stethoscope.