A/T - THM 440-T4 Harsh 3-2 Downshifts
Bulletin No. T 87-43File in Group 7
Number 148
Corp. Ref. No. 677122
Date Dec. '86
SUBJECT: THM 440-T4 HARSH 3-2 DOWNSHIFTS -- HIGH ALTITUDE
MODELS AFFECTED: 1985-1986 DE VILLE AND FLEETWOOD 1986 ELDORADO AND SEVILLE
Some 1985-1986 vehicles equipped with a 440-T4 transaxle may exhibit a harsh 3-2 coastdown shift when operated in designated high attitude areas.
This condition is a result of the 3-2 control valve spring calibration.
Correction can be achieved by installing a new 3-2 control valve spring. A service package has been released which contains:
Spacer Plate Gaskets (2) Instruction Sheet Spring, 3-2 Control Valve
The following part numbers apply to specific transaxles by model code.
Transaxle
Service Package Model Identification
8646981 5AC, 5AY, 6ACH, 6AWH
8646982 5AM, 6AAH, 6AMH, 6AFH
6APH, 6ASH, 6AYH
Refer to the appropriate Service Information Manual 440-T4 Transaxle Unit Repair section for control valve assembly service procedures.
Note: The installation of the 3-2 control valve spring package may result in a flare/slide bump condition on a 3-2 downshift when the vehicle is driven in a non-high altitude area.
This should be considered a normal operating characteristic and should not effect the durability of the unit over a short period of time (i.e., vacation periods, etc.). If the vehicle is expected to return to operation in a high altitude area, no corrective action should be attempted.
Use Operation Number K6570 at 2.7 hours for De Villes and 3.2 hours for Eldorados and Sevilles.
EPA Designated High Altitude Counties:
DESIGNATED HIGH ALTITUDE COUNTIES* Requiring High Altitude Emission Control
STATE OF ARIZONA Apache Navajo
STATE OF COLORADO
Adams Jefferson
Alamosa Lake
Arapahoe La Plata
Archuleta Larimer
Boulder Las Animas
Chaffee Lincoln
Clear Creek Mesa
Conejos Mineral
Costilla Moffat
Crowley Montezuma
Custer Montrose
Dolores Morgan
Delta Ouray
Denver Park
Douglas Pitkin
Eagle Pueblo
Elbert Rio Blanco
El Paso Rio Grande
Fremont Routt
Garfield Saguache
Gilpin San Juan
Grand San Miguel
Gunnison Summit
Hinsdale Teller
Huerfano Washington
Jackson Weld
STATE OF IDAHO
Bannock Custer
Bear Lake Franklin
Bingham Fremont
Blaine Jefferson
Bonneville Madison
Butte Minidoka
Camas Oneida
Caribou Power
Cassia Teton
Clark Valley
STATE OF MONTANA
Beaverhead Madison
Deer Lodge Meagher
Gallatin Park
Jefferson Silver Bow
STATE OF NEBRASKA
Banner Sioux
Kimball
STATE OF NEVADA
Carson City Humboldt
Douglas Lander
Elko Lyon
Esmeralda Mineral
Eureka Storey
White Pine
STATE OF NEW MEXICO
Bernalillo Mora
Catron Rio Arriba
Colfax Sandoval
Curry San Juan
De Baca San Miguel
Grant Santa Fe
Guadalupe Sierra
Harding Socorro
Lincoln Taos
Los Alamos Torrance
Luna Union
McKinley Valencia
STATE OF OREGON
Lake
STATE OF UTAH
Beaver Piute
Box Elder Rich
Cache Salt Lake
Carbon San Juan
Daggett Sanpete
Davis Sevier
Duchesne Summit
Emery Tooele
Grand Uintah
Iron Utah
Juab Wasatch
Kane Wayne
Millard Weber
Morgan
STATE OF WYOMING
Albany Natrona
Carbon Niobrara
Converse Park
Fremont Platte
Goshen Sublette
Hot Springs Sweetwater
Johnson Teton
Laramie Uinta
Lincoln Weston
*Counties which have substantially all of their area above 4000 ft. Ref. Federal Register, Vol. 42, No. 76, April 20, 1977, pg. 20464