Control Valve/Oil Pump Rotor and Slide - Servicing
Bulletin No. T 83-105
File In Group 7
Number 76
Date June '83
SERVICE PROCEDURE FOR THE CONTROL VALVE AND OIL PUMPROTOR AND SLIDE - THM 125C
Beginning mid-April, 1983, service parts became available to separately replace the oil pump rotor and slide of the control valve and oil pump assembly, on all THM 125C transaxles. The service procedure in this bulletin must be followed to assure proper end clearance of the replacement oil pump rotor and/or slide into the original control valve and oil pump assembly.
SERVICE PROCEDURE
NOTICE: DO NOT attempt to service the oil pump rotor if either the pump pocket or auxiliary valve body/pump cover surfaces are scored. Servicing of the oil pump rotor and slide should be performed ONLY if the selective pump rotor, pump drive shaft or the pump slide show signs of wear.
FIGURE 1 - Oil Pump Assembly:
1. DISASSEMBLY OF THE OIL PUMP
A. Disassemble the oil pump assembly (Figure 1) following procedures outlined in the Service Information Manual.
FIGURE 2 - Measuring Pump Rotor:
II. SELECTING THE PUMP ROTOR AND/OR SLIDE
A. Use a vernier micrometer to measure the original pump rotor and/or slide thickness accurately (Figure 2). Measure on flat, undamaged surfaces to obtain the most accurate reading.
NOTE: The replacement part will provide the same end clearance originally built into the transaxle. The proper end clearance specification is 0.066 mm to 0.092 mm (0.0026" to 0.0036").
B. Using the original part measurement, order a replacement part using the following selective charts:
1982-1983 THM 125C SELECTIVE PUMP ROTOR (15 TOOTH)
PART NO. THICKNESS (MM) THICKNESS (IN.)
8637768 17.917-17.929 0.7055-0.7059
8637769 17.930-17.942 0.7060-0.7064
8637178 17.943-17.955 0.7065-0.7069
8637179 17.956-17.968 0.7070-0.7074
8637180 17.969-17.981 0.7075-0.7079
1982-1983 THM 125C SELECTIVE PUMP SLIDE
PART NO. THICKNESS (MM) THICKNESS (IN.)
8631800 17.955-17.967 0.7070-0.7074
8631801 17.968-17.980 0.7075-0.7079
8631802 17.981-17.993 0.7080-0.7084
8631803 17.994-18.006 0.7085-0.7089
8631804 18.007-18.020 0.7090-0.7094
C. Hone both sides of the replacement rotor and/or slide to remove any burrs, and measure the replacement parts with micrometer to assure the proper selection.
NOTE: Incorrect rotor selection could result in a damaged control valve and oil pump assembly, a sheared pump drive shaft and/or low oil pressure. Incorrect slide selection could result in incorrect line pressures.
III. ASSEMBLY
A. Reassemble the oil pump assembly following procedures outlined in the Service Information Manual.
B. After assembling the control valve and oil pump assembly onto the transaxle, check for proper rotor and slide end clearance by turning the pump drive shaft. The pump rotor should turn freely. If the pump rotor does not turn freely, recheck the pump rotor and/or slide selection.
C. Install the transaxle into the vehicle.
D. Before road testing the vehicle, install an oil pressure gage into the transaxle and check oil pressure. Refer to the "Preliminary Check Procedure" in the Service Information Manual for oil pressure specifications.
FIGURE 1 - Oil Pump Assembly:
IV. OTHER OIL PUMP SERVICE PARTS (FIGURE 1)
A. Listed below are parts previously released to service the oil pump of the control valve pump assembly.
ILL.
NO. PART NAME PART NUMBER
18 THM 125C Oil Pump Drive Shaft (1982-1983) 8637777
357 Pump Drive Shaft Seal 8637569
354 Pump Drive Shaft Bearing Assembly 8631277
351 Pump Vane Ring 8631279
352 Pump Vane 8631280
346-347 Pump Slide Seal Package 8631947
344 Pump Cover Sleeve 8631288
359 Pump Priming Spring 8631717
345 Slide Pivot Pin 8628273