Century Estate Wagon L4-151 2.5L (1985)
Shift Modulator: All Technical Service Bulletins
A/T - Harsh 3-2 Downshifts
Bulletin:
92-74T60-8
Date:
Mar. '92
Ref. No.:
92-175-74T60
Corp. Ref. No.:
977162R
SUBJECT:
HARSH SHIFT CONDITIONS AND ON CAR SERVICE INFORMATION FOR HARSH 3-2 DOWNSHIFTS WITH 4T60 TRANSAXLE
MODELS AFFECTED:
1985-92 CENTURY
1988-92 REGAL
1985-90 ELECTRA/PARK AVENUE
1986-91 LESABRE
1986-90 RIVIERA
1988-90 REATTA
THIS BULLETIN CANCELS AND REPLACES BULLETIN 90-7440-7.
THIS BULLETIN UPDATES THE 3-2 CONTROL VALVE SPRING LISTING AND ADDS THE 1991 AND 1992 MODEL YEARS.
IMPORTANT:
Before performing any service, verify that the customer's concern is a 3-2 downshift and not a 2-1 downshift concern A TECH I or other scan tool can be
used as an aid to make this determination. Also, it would be an aid for diagnosis to put the transaxle in manual 3rd, or 2nd before and after the concern to
determine actual gears of the shift complaint.
NOTICE:
DO NOT USE General Motors limited slip differential lubricant additive or equivalent to eliminate undesirable "shift-feel," reduce harsh shifting, or to
minimize torque converter apply/release "shudder." This will prematurely distress the clutches and bands in the transaxle/transmission by elongating
shift-engagement times and increasing slippage between surfaces, even though it might provide better shift-feel for the customer at first. Also, the static
capacity (a measure of load-holding capacity) will be reduced by at least 50 percent (i.e., the transaxle/transmission will only handle one half the
Combined Gross Vehicle Weight as it did before without slipping).
THE BOTTOM LINE: The customer will be pleased at first, but will be back to the dealership with a distressed transaxle/transmission.
