SERVICE MANUAL Fig.  13 Fig.  14 5. Clean  seal  groove.    Lubricate  the  groove  and the new  seal with  an  IH  251H  EP grease or equivalent   to   NLCI    #2    multi    purpose    lithium grease.   Install the new seal.   Be sure  the seal is seated,  by running your finger around the seal inside diameter and press seal in place. 6. Position  a  new  guide  ring  on  each  side  of  the seal   (Fig.    13).      The    wider  flange  side  will  be away    from    the    seal.        Align    the    skive    cuts approximately 1800 apart. 7. Install smaller pushrod plate on pushrod if it was removed.      Be   sure   to   thoroughly   clean   screw threads   and   threaded    holes    in    the    pushrod. Apply  Loctite  General  Purpose  Lock  N’  Seal  to the screw threads. Install  screw  to  secure  small plate  in  place.    Tighten  screw  to  20  N.m  (15  ft lbs). 8. Apply   a   small   amount   of   lubricant   to   tip   of pushrod and insert the pushrod through the seal from the service brake chamber side of case. 9. Position   return   spring   in   case   and   compress spring with large pushrod plate so that the screw can be threaded in the pushrod.   Use  General Purpose    Lock    N’  Seal  on  the  screw.    Tighten this   screw   to   20   N.m   (15   ft   lbs).      The   large pushrod  plate  must  be  toward  the  spring  brake side of unit.  The screws can be tightened using one screwdriver in a vise to hold one screw and tighten the opposite screw (refer to step 2). 10. Check   the   alignment   of   return   spring   in   case and  to  large  pushrod      plate.  Straight  alignment is important for positive rod sealing. 11. Inspect the diaphragms; replace them if damaged or more than a year old. 12. To  complete  the  reassembly  of  the  unit  refer  to REPLACE SPRING BRAKE UNIT OR SERVICE BRAKE  DIAPHRA(G  and  complete  steps  9,  10 and 11.  Then complete steps 10, 11, 12 and 13 of REPLACE SPRING BRAKE DIAPHRAGM. SERVICE  SPRING  BRAKE  UNIT  WITH  SUSPECTED DEFECTIVE POWER SPRING OR DEFECTIVE RELEASE MECHANISM WARNING Do not attempt to disassemble power spring unit  while  it  is on  the vehicle;  even though a   broken   power   spring   is   confirmed,   it   is important   to   manually   release   the   spring brake   unit   before   any   disassembly   is   per- formed.    Accidental    release    of  the  power spring  will  cause  spring  brake  components to    be  hurled  with  force  which  could  strike persons  in  area  causing  serious    personal injury or death. Refer to MANUAL RELEASE  OF  SPRING BRAKE. 1. Refer  to  text  REPLACE  SPRING  BRAKE  DIA- PHRACM.         Pay      special      attention      to   the CAURION references.  Perform steps 1 thru and including     7     to     remove     spring     brake     head assembly. 2. Use    a    3.175    mmn    (1/8")    diameter    punch. Support  the  release  bolt  and  knock  out  lock  pin in  release  bolt  as  illustrated  in  Fig.    15.    Then remove the slotted release nut. 3. Use  a  screwdriver  to  pop  off  the  piston  plug  in the center of the piston (Fig. 16). Fig.  15 Fig.  16 4. Insert  head-spring  piston  subassembly  in  press (Fig.  17).   It  is  important  to position one 356- 381    mn    (4-5’")    diameter    slit-tube    under    the assembly supporting the piston and another one over the assembly between the head and the flat plate under the press ram.  Without these tubes, the final safe disassembly cannot be accomplished.  After the ram  touches the plate, the ram must be able to travel a minimum of 203 mm  (8")  away  from  the  assembly.    Without  the length   of   travel   available   the   spring   will   not completely relax. CTS-4101W - Page 9