FIRM 1-2/3-2 FLARE SHIFTS/125C NEW CONTROL VALVE ASSEMBLY

MODELS AFFECTED: 1983 THM 125C TRANSMISSION MODEL CB

The 1983 THM 125C CB model transmission may experience a firm 1-2 shift or 3-2 shift flare at times.

To correct this shift condition, a new control valve assembly went into production in early November, 1982. This new control valve assembly will soften the 1-2 shift feel and eliminate the 3-2 shift flare.

When servicing any CB model THM 125C transmission for this shift condition built prior to transmission serial number CB-28411, use service package part number 8643998. Refer to the following service procedure for installation.

SERVICE PROCEDURE

1. Remove the control valve assembly from the transmission.

2. (Figure #1) Remove the retaining pin from the 1-2 accumulator bore in the control valve assembly.

NOTICE: Note the location of the hole in the 1-2 accumulator bushing that the retaining pin locates thru.

3. Remove the 1-2 accumulator plug, valve, bushing, and spring and replace the valve, spring and bushing with parts contained in service package #8643998. (1-2 accumulator spring will be orange in color and will be the smallest spring in diameter of the two springs contained in the package.)

4. Install the retaining pin into the bore thru the top hole in the bushing. The pin must be flush or below the bottom face of the valve control assembly.

5. Remove the spring retaining sleeve from the 3-2 control valve bore in the valve body (Figure 1).

6. Replace the 3-2 control valve spring with the spring contained in the service package. (The 3-2 control valve spring will be yellow in color and larger in diameter than the 1-2 accumulator spring.)

7. Replace the spring retaining sleeve into the valve body. The retaining sleeve must be flush or below the bottom face of the control valve assembly.

8. Install the control valve assembly onto the transmission following procedures outlined in the service manual.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.