Subject: New Control Valve Assembly

VEHICLE APPLICATION:

Firebird Models

FIGURE 2 - CONTROL VALVE ASSEMBLY:

Change To Assembly Components: (Figure 2)

A new Control Valve Assembly (67) and Valve Body Spacer Plate for all 1988 THM 700-R4 transmissions. The new Control Valve Assembly consists of revised 1-2 and 3-4 shift valve trains. With the change to the 1-2 valve train, two valves and one sleeve have been eliminated. The lo range downshift valve (321), the lo range control sleeve (320) and the 1-2 lo range upshift valve (353) have been eliminated from the 1988 THM 700-R4 Control Valve Assembly.

These new valve trains improve consistency for the 1-2 and 3-4 shifts.

With the changes made to the control valve assembly, the #9 Lo-Detent Checkball has been eliminated from 1988 THM 700-R4 transmissions.

FIGURE 3 - CHECK BALL & OIL SCREEN LOCATIONS:

Service Action: (Figure 3)

A 1988 Control Valve Assembly CANNOT be used on any past model THM 700-R4 transmission. In addition, when servicing a 1988 THM 700-R4 transmission, DO NOT install a #9 checkball in the case.

Installing a #9 checkball in a 1988 model case could cause the lo and reverse clutch to burn.
Service Manual Reference:

This material is included in your 1988 Service Manual Unit Repair Section. All material that is new for 1988 or was not included in your 1987 Service Manual is noted by an asterisk in the 1988 Unit Repair Table of Contents.