Cutlass L4-138 2.3L VIN A FI HP (1990)
The shift speed charts, minimum and maximum oil pressures and wiring diagrams have not changed. Use the cross-reference chart in Figure 1 to find the
previous 1990 model; then reference previous model data listed (oil pressure, wiring diagrams and shift speed charts) to service the new 1990 model. For
example, the new 1990 model OWMH will be serviced by the 1990 OBHH model data.
For the new channel plate, input clutch wave plate and input clutch plate, the following parts were modified to eliminate the input accumulator
components:
^
Four instead of three input clutch (steel or reaction) plates (647). The new input clutch plate will assemble between the added wave plate (810) and
input clutch (fiber) plate assembly (The new input clutch plates will also be thinner by 0.722 mm (0.028") to make room for the added wave plate
and input clutch plate). The previous input clutch plates will still be available. Do not mix the previous and new input clutch plates; this will cause
a durability concern.
^
Channel plate (404) will not have the input clutch accumulator bore and components. A wave plate will be added to the input clutch assembly that
will replace the function of the accumulator. The new channel plate will also have porting changes that will help ensure that two ports will never
be opened simultaneously, which causes distress to the 4th clutch assembly when the shift cable is not set correctly or is kinked or binding. The
previous channel plate with the input accumulator bore and components and the new channel plate are not interchangeable. The channel plate with
the input accumulator will still be available.
^
New manual valve (403) will have changes to the valve lands and be reduced 0.25 mm (0.010") in diameter for the new porting changes to the
channel plate. The previous and new manual valves are not interchangeable. The new manual valve will assemble into the previous production
channel plate, but the transaxle will not function because of excessive leakage due to the differences in sizes.
^
New inside detent lever (704) will have the manual link hole location changed for a different "throw" of the manual valve. The previous and new
inside detent lever are not inter-changeable even though the parts will physically assemble. The new inside detent lever must be used with the new
manual valve and channel plate. The previous inside detent lever must be used with the previous manual valve and channel plate. The identifier for
the new Cutlass Supreme inside detent lever is an added square hole. The previous Cutlass Supreme inside detent lever is gold in color. Some of
the early new Cutlass Supreme inside detent levers may be gold in color and have the added square hole. The gold color will be discontinued and
the square hole will be the only identifier for the new Cutlass Supreme inside detent lever. The previous inside detent lever will still be available
for models that just need replacement of the lever for 1987 and prior model years.
^
Input housing (632) has been revised by moving the snap ring groove up 1.50 mm (0.059") to make room for the wave plate and extra input clutch
plate in the input clutch. The previous and new input housings are not interchangeable because of the differences in clutch pack free play and
travel. The previous input housing will still be available.
DATE OF PRODUCTION CHANGE:
All HYDRA-MATIC 4T60 (THM 440-T4) transaxles are built with the new channel plate, input housing (with the wave plate and extra input clutch
plate) and new model codes starting January 16, 1990 (Julian Date 016).
SRTA MODEL INFORMATION:
^
SRTA models with the new 1990 model codes may not have all the new components listed in this
Service Bulletin. These parts include: new input housing with the wave plate and four thinner input clutch plates and the new production channel
plate without the input accumulator components.
