A/T - 3L80 and 4L80-E 1-2 Shift Shudder

91chevy23

GMC NUMBER: 91-7A-158

GROUP: 7A Automatic Transmission

DATE: October, 1991


CORPORATE NUMBER: 177115


SUBJECT: 1-2 SHIFT SHUDDER, HARSH OR DOUBLE FEEL (NEW PISTON AND RING SERVICE PACKAGE-ASSEMBLY)

MODELS: 1991 C/K AND R/V/G/P W/ 4L80E AND 1990 C/K AND R/V/G/P WITH 3L80

Figure 1:

Some 1990 C/K and R/V/G/P trucks with HYDRA-MATIC 3L80 transmissions and 1991 C/K and R/V/G/P trucks with 4L80-E transmissions may experience a 1-2 shift shudder or harsh double feel. This is caused by fluid leaking past the rear accumulator piston seals. A new piston and ring assembly package was released that eliminates this condition. Refer to the on-vehicle section of the appropriate service manual for proper replacement procedures.

Date of Production Change: (Figure 1)

Starting April 18, 1991 (Julian Date 108) all HYDRA-MATIC 4L80-E/4L80-EHD models were built with the new Accumulator Piston and Seals.

Figure 2:

PARTS INFORMATION: (Figure 2)

Part Part Name
Number
8680929 Piston and Ring Assembly,
Rear Accumulator

New Piston and Ring Assembly can be used with older model cases. When installing, use TRANSJEL J36850 or equivalent to aid in assembly.

Old Piston Ring and Ring Assembly cannot be used on new cases.

Parts are currently available from GMSPO.