A/T Control Valve, Oil Pump, Rotor and Slide - Service
Number 83-I-96 Section 7 Date 06/83Subject: SERVICE PROCEDURE FOR CONTROL VALVE, OIL PUMP, ROTOR AND SLIDE - THM 125/125C
Beginning mid-April 1983, service parts became available to service the oil pump rotor and slide of the control valve and oil pump assembly on all THM 125/125C transaxles.. This service procedure must be followed to assure proper end clearance.
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:
1. DISASSEMBLY OF THE OIL PUMP
Disassemble the oil pump (see Figure 1) following procedures outlined in your Service Manual.
Figure 2:
II. SELECTING THE PUMP ROTOR AND/OR SLIDE
A. Use a micrometer to measure the original pump rotor and/or slide thickness accurately (see Figure 2). Measure on flat, undamaged surfaces to obtain the most accurate reading.
B. Using the original part measurement, order a replacement part using the following selective charts:
1980-1981 THM 125 SELECTIVE PUMP ROTOR (20 TOOTH)
PART
NUMBER THICKNESS (MM) THICKNESS (IN)
8631495 17.943 - 17.955 0.7065 - 0.7069
8631496 17.956 - 17.968 0.7070 - 0.7074
8631497 17.969 - 17.981 0.7075 - 0.7079
8631514 17.982 - 17.994 0.7080 - 0.7084
8631515 17.995 - 18.008 0.7085 - 0.7089
NOTICE: The replacement part will provide the same end clearance that the transaxle was originally built with. The proper end clearance specification is 0.066 mm to 0.092 mm (0.0026" to 0.0036").
1982-1983 THM 125C SELECTIVE PUMP ROTOR (15 TOOTH)
PART
NUMBER 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
1980-1983 THM 125/125C SELECTIVE PUMP SLIDE
PART
NUMBER 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.
NOTICE: 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 your Service 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 your Service Manual for oil pressure specifications.
Figure 1:
IV. OTHER OIL PUMP SERVICE PARTS (Refer To Figure 1)
Listed below are parts previously released to service the oil pump of the control valve pump assembly.
ILL. PART
NUMBER PART NAME NUMBER
18 THM 125 Oil Pump Drive Shaft (1980-1981) 8631869
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