Because during the bonding process, the inner arc radius of the brake pad and the outer radius of the shoe are not Anastomosed, bonded product creates a gap between the lining and the shoe, which is bonded to the shoe. One of the defects. The reason for the first one is the size of the adjustment machine for the welding of the rear shoe. Did not meet the requirements of the standard; the second is after a period of processing after the welding of the shoe. The stress on the solder joints causes the shoe to deform.