SERVICE MANUAL Fig. 9 Sectional View of E7 Brake Valve 1 STEM 2 NUT, Spring Seat 3 SPRING, Stem 4 GUIDE, Stem Spring 5 NUT, Lock 6 SEAT, Spring 7 RETAINER 8 PISTON, Primary 9 SPRING, Rubber 10 PISTON, Lower Static 11 SPRING, Primary Piston Return 12 BODY 13 PISTON, Relay 14 SPRING, Relay Piston Return 15 PISTON, Upper Static 16 VALVE, Secondary Inlet & Exhaust 17 RING, Retaining 18 VALVE, Primary Inlet & Exhaust 19 RING, Retaining 20 GROOVE, Locking 5. Install  O-rings  on  relay  piston  (13)  and  primary piston (8). 6. Position rubber spring (9), concave side down, in primary piston (8) and place spring seat (6), flat side up, over rubber spring. 7. Install spring seat nut (2) on primary piston  with hex  head  closest  to  spring  seat  and  rotate  nut clockwise until top surface of spring seat is even with top surface of piston (8). 8. Position relay piston spring (14), which is lighter of the two piston return springs, relay piston (13), primary piston spring (11) and primary piston (8) in   lower   static   piston   (10).      Compress   both primary   and   secondary   pistons   in   lower   static piston.  Hold them manually or mechanically. A   screwdriver   may   be   used   by   inserting   it   through   a rectangular opening in static piston into locking groove (20) in primary piston. 9. Insert stem (1) through exhaust passage of relay and  primary  pistons  and  engage  a  screwdriver with   slot   in   head   of   stem;   then   position   stem spring  (3),  spring  guide  (4)  on  spring  seat  nut (2). 10. Compress guide spring assembly and install lock nut (5) on stem.  Torque nut to 2.3 -3.4 N.m (20 - 30 in lbs). Torque is a specified value for assembly; after assembly, torque value will fall off.Do not retorque nut. 11. Remove   screwdriver   from   lower   static   piston assembly. CTS-4079 - CHAPTER Page 10