Transmission Control Systems: Service and Repair
Special Tools:
To service the 1-2 or 2-3 accumulators or the overdrive or reverse servo assemblies use the following procedure.
REMOVAL
1. Remove the main control valve body. This illustration shows the position of the overdrive servo, the reverse band servo piston and rod, 2-3 accumulator piston and the 1-2 accumulator piston.
2. Remove the 2-3 accumulator spring retainer.
3. Remove 2-3 accumulator piston.
4. NOTE: If tool is not available, extreme care must be taken. Spring pressure will force overdrive servo piston assembly out of case. Case bore damage may result from trying to pry on overdrive servo piston retainer.
Use Servo Piston Remover/Replacer 307-251 (T92P-70023-A) to compress the overdrive servo piston return spring. Use snap-ring pliers to remove retainer ring.
5. Remove piston assembly. Remove overdrive servo piston return spring.
6. Use Servo Piston Remover/Replacer 307-251 (T92P-70023-A) to contact the reverse band servo cover and compress return spring and remove accumulator piston 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.
8. Apply downward pressure on 1-2 accumulator cover using Servo Piston Remover/Replacer 307-251 (T92P-70023-A). Using snap-ring pliers, remove 1-2 accumulator piston retaining ring.
9. NOTE: Carefully note the location of the 1-2 accumulator spring and assemble in the same positions. Some models may use two 1-2 accumulator springs. The accumulator piston may also vary with applications.
Remove accumulator piston and 1-2 accumulator spring.
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, or when the reverse band has been replaced, determine the correct length of the reverse servo piston and rod, proceed as follows:
a. Lubricate the reverse piston seal to facilitate assembly and to prevent damage to the seal.
b. Install the reverse servo piston and return spring. Do not install the piston cover or retaining ring.
c. Install Servo Piston Selection Tool 307-073 (T80L-77030-A). Tighten the band apply bolt on Servo Piston Selection Tool 307-073 (T80L-77030-A) to 5.6 Nm (50 inch lbs.).
d. Attach Dial Indicator with Bracketry 100-002 (TOOL-4201-C) or equivalent and position the indicator stem on the flat portion of the piston. Zero the dial indicator.
e. Thread the bolt out of the selector tool until the piston stops against the bottom of the tool.
f. 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
74.56 mm (2.936 inch) 1 groove
75.92 mm (2.989 inch) 2 grooves
77.29 mm (3.043 inch) 3 groove
Length of rod measured from piston surface to end of rod.
Select the proper rod to bring the servo piston travel within specification.
g. Lubricate the cover seal to facilitate assembly and to prevent damage to the seal.
h. Remove the servo selection tool and dial indicator.
2. Install Servo Piston Remover/Replacer 307-251 (T92P-70023-A) to transmission case.
3. Tighten screw on Servo Piston Remover/Replacer 307-251 (T92P-70023-A) to allow enough clearance to install retaining ring.
4. CAUTION: Make sure reverse servo retaining ring is completely seated before removing tool or servo cover will not seat.
Install reverse servo retaining ring and remove tool.
5. 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 307-251 (T92P-70023-A), install piston assembly into the case and compress overdrive servo piston return spring.
6. 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 accumulator in the following order:
^ accumulator piston
^ accumulator piston spring
^ rear band servo spring retainer
8. Assemble the components for 1-2 accumulator in the following order:
^ 1-2 accumulator spring
^ accumulator piston
^ 1-2 accumulator spring
^ cover and seal assembly
^ accumulator piston retaining ring
9. Install the 1-2 accumulator assembly and spring to case. Install cover and seal assembly. Install retaining ring.
10. Install main control valve body.
11. Install fluid filter and grommet.
12. NOTE: Transmission oil pan to case gasket is reusable if not damaged.
Clean, inspect and install oil pan to case gasket and transmission pan. Tighten all bolts to 12-15 Nm (107-132 inch lbs.).
13. Install transmission shift linkage to manual control lever.
14. Pour 4.7 liters (5 quarts) of MERCON V Automatic Transmission Fluid XT-5-QM or equivalent MERCON V approved fluid into fluid filler tube.
15. Reconnect battery ground cable.
16. Start the engine and add specified fluid as required to achieve the proper fluid level.
17. Check the transmission for leaks.