TM 10-3930-659-34 4-51. SERVICE BRAKE DISC REPLACEMENT (Con’t). NOTE There are four service brake discs on forklift truck.  Two on front axle and two on rear axle.  All brake discs are removed and installed the same way. Front axle left service brake disc is illustrated. a. REMOVAL 1. Using feeler gage, measure service brake disc (1) to pinion shaft (2) backlash.  If backlash is greater than 0.040 in.  (1.016 mm), discard service brake disc in step 2. NOTE Brake backing plate is held In place on ring gear with three dowel pins. 2. Remove service brake disc (1) and brake backing plate (5) from ring gear (4). 3. Mark ring gear (4) and axle housing (3) to aid during installation. 4. Remove ring gear (4) and pinion shaft (2) from axle housing (3). 5. Remove three dowel pins (6) from ring gear (4). 4-188