A/T - THM 440T4/4T60E New Clutch Plates
90buick14 Bulletin 91-7-1Date Oct. '90
Ref. No. 91-046-7
Corp. Ref. No. 077136
SUBJECT: NEW PLATES - 4TH CLUTCH REACTION, FORWARD CLUTCH, LO AND REVERSE WAVED
MODELS AFFECTED: 1980-91 ALL MODELS WITH 3T40 (THM 125C) 4T60 (THM 44OT4) OR 4T60E
Figure 1 - New 4th Clutch Plate Assembly:
BULLETIN COVERS: (Figure 1)
New 4th clutch reaction plates for the Hydra-Matic 4T60 and 4T60-E transaxles; and new forward clutch and lo and reverse waved plates for the Hydra-Matic 3T40. All three new plates will have blackened edges, and the flat surfaces will have some lightly blackened areas. The new plates are made with a new process to aid manufacturing. A by-product of this new process is that the edges will be blackened, and the flat surfaces will have some lightly blackened areas. Figure 1 shows an example of a 4th clutch reaction plate with blackened areas and edges. The forward clutch and lo and reverse clutch waved plates will have similar markings.
SERVICE PROCEDURE:
Replace the 4th clutch reaction plates if severely warped. Replace the 4th clutch reaction plates, forward clutch waved plate, or the lo and reverse waved plates if they have obvious large overheated, discolored areas that mate to the fiber material plate. Heat discoloration on the plate back side (non-fiber mating surfaces) should be considered normal, unless the plate is warped.
DATE OF PRODUCTION CHANGE:
Beginning July 25, 1990 (Julian Date 206), some 1991 Hydra-Matic 4T60 and Hydra-Matic 4T60-E transaxles were built with the new 4th clutch reaction plates. As of September 10, 1990 (Julian Date 253) all models should have the new reaction plates.
Beginning October 10, 1990, (Julian Date 283) all 1991 Hydra-Matic 3T40 transaxles are being produced with the new forward clutch and lo and reverse waved plates.
SERVICE PARTS INFORMATION:
The new parts will be available when the previous parts are depleted.
SERVICE MANUAL REFERENCE:
Refer to the appropriate Service Manual for proper disassembly and assembly procedures.