Regarding your question, I suggest you check whether the pipe fixing the brake cylinder is stuck due to corrosion, resulting in the brake cylinder not fully returning and locking and making abnormal noise. The conduit is located at the position where the brake cylinder is fixed to the suspension, outside the fixing screws of the brake cylinder and the suspension, that is, in the two holes of the brake cylinder where the fixing bolts are installed. You can remove the brake cylinder, take down the guide pipe, polish it with fine sandpaper, then butter it, and finally load the car, and the problem should be solved.