Main Control Components

Removal

1. Remove the main control valve body (7A100). Refer to Main Control Valve Body in the In-Vehicle Service portion of this section.

   This illustration shows the position of the overdrive servo, the reverse band servo piston and rod (7D189), 2-3 shift accumulator piston (7F251) and the 1-2 shift accumulator piston.

   

2. Remove the 2-3 shift accumulator spring retainer and spring.

   

3. Remove 2-3 shift accumulator piston.

   

   Overdrive Servo

   

4. NOTE: If tool is not available, extreme care must be taken. Spring pressure will force overdrive servo piston (7F200) assembly out of case (7005). Case bore damage may result from trying to pry on overdrive servo internal retaining ring.

   Use Servo Piston Remover/Replacer T92P-70023-A to compress the overdrive servo piston return spring (7F201). Use snap-ring pliers to remove retaining ring.

   

5. Remove piston assembly. Remove overdrive servo piston return spring.

   

   Reverse Band Servo

   

6. Use Servo Piston Remover/Replacer T92P-70023-A to contact the reverse band servo cover (7D036) and compress return spring. Remove internal retaining ring.

7. NOTE: The length of the rod attached to the piston is graded for three different lengths. Therefore, they should not be installed in any transmission other than the transmission from which they were removed.

   Remove reverse band servo cover, reverse band servo piston and rod and reverse band servo spring (7D031).

   

8. Apply downward pressure on 1-2 accumulator cover using Servo Piston Remover/Replacer T92P-70023-A. Using snap-ring pliers, remove accumulator piston retaining ring (7384).

   

9. NOTE: Carefully note the location of the 1-2 accumulator outer springs (7G267) and assemble in the same positions. Some models may use two 1-2 accumulator outer springs. The accumulator piston may also vary with applications.

   Remove cover and 1-2 accumulator outer spring. Use reverse snap-ring pliers to remove accumulator piston and 1-2 shift spring (7F284).

Installation

1. NOTE: This is not an ordinary installation procedure and does not compensate for band wear.

   Install reverse band servo spring, reverse band servo piston and rod. When piston and rod assembly replacement becomes necessary, determine the correct length of the reverse servo piston and rod, proceed as follows.

   1. Lubricate the reverse piston seal to facilitate assembly and to prevent damage to the seal.
   2. Install the reverse servo piston and return spring. Do not install the piston cover or retaining ring.
   3. Install Servo Piston Selection Tool T80L-77030-A. Tighten the band apply bolt on Servo Piston Selection Tool T80L-77030-A to 5.6 Nm (50 lb-in).

      

   4. Attach Dial Indicator with Bracketry TOOL-4201-C or equivalent and position the indicator stem on the flat portion of the piston. Zero the dial indicator.

      

   5. Thread the bolt out of the selector tool until the piston stops against the bottom of the tool.
   6. Read the amount of piston travel on the dial indicator.
      • If the travel is 2.845-6.020 mm (0.112-0.237 inch), the piston length is within specification.
      • If the travel is not within specification, selective pistons are available in the following lengths:
      • ID
      • 74.56mm (2.936 inch) 1 groove
      • 75.92mm (2.989 inch) 2 grooves
      • 77.29mm (3.043 inch) 3 grooves
      • Length of rod measured from piston surface to end of rod.
      • Select the proper rod to bring the servo piston travel within specification.
   7. Lubricate the cover seal to facilitate assembly and to prevent damage to the seal.
   8. Remove the servo selection tool and dial indicator.

2. Install reverse band servo cover.

3. Install Servo Piston Remover/Replacer T92P-70023-A to transmission case.

4. Tighten screw on Servo Piston Remover/Replacer T92P-70023-A to allow enough clearance to install retaining ring.

5.  CAUTION: Make sure reverse servo retaining ring is completely seated before removing tool.

   Install reverse servo retaining ring and remove tool.

   

6. Install overdrive servo piston return spring and overdrive servo piston assembly. Verify tip of piston assembly engages the pocket of overdrive band. Using Servo Piston Remover/Replacer Tool T92P-70023-A, install piston assembly into the case and compress overdrive servo piston return spring. Tighten tool until piston is below retaining ring groove and install retaining ring, remove tool.

   

   

7. NOTE: Retainer is secured by main control.

   Install the components for 2-3 shift accumulator in the following order:

   • Upper accumulator seal (7F250).
   • Accumulator piston.
   • Lower accumulator seal (7F249).
   • Accumulator piston spring (7F285).

   

8. Assemble the components for 1-2 shift accumulator in the following order:

   • Accumulator piston seal (7F248).
   • Accumulator piston.
   • Lower accumulator seal.
   • Accumulator outer spring.
   • Cover and seal assembly.
   • Accumulator piston retaining ring.

   

   Item	Part Number	Description
   1	7F248	Accumulator Piston Seal
   2	7F251	Accumulator Piston
   3	7F249	Lower Accumulator Seal
   4	7G267	1-2 Accumulator Outer Spring
   5	7G300	Cover and Seal Assembly
   6	7384	Accumulator Piston Retaining Ring

9. Install the 1-2 shift accumulator assembly and spring to case. Install cover and seal assembly. Install retaining ring.

   

10. Refer to Main Control Valve Body, Installation in the In-Vehicle Service portion of this section to finalize assembly.