Aerostar 2WD V6-245 4.0L (1990)
Torque Converter: Description and Operation
DESCRIPTION
The torque converter provides fluid coupling and torque multiplication and acts as a shock absorber. It couples the engine to the gear train as a fluid
coupling or fluid clutch, providing hydraulic drive or coupling between engine and gear train. In certain operating conditions, it multiplies torque,
providing extra reduction to match engine output to the driveshaft. It also absorbs the shock of gear shifting in the drive train.
CONSTRUCTION
The A4LD 10-1/4 inch converter resembles other converters, but has a hydraulic piston plate added. This feature changes the hydraulic coupling to a
more efficient mechanical coupling.
OPERATION
1. Converter clutch application is based on both engine speed and vehicle speed by combined transmission hydraulics and on-board computer
electronic controls. When this clutch engages there is a mechanical connection between the engine and rear wheels. This feature is provided to
improve both driveline efficiency and fuel economy. Whenever the clutch is engaged, the vehicle may respond in ways similar to driving with a
manual transmission. This is normal and should not be considered as adverse or indicating need for servicing.
2. Converter clutch engagements and disengagements are scheduled hydraulically but can be overridden electronically. The converter clutch is
inhibited from engaging when engine coolant temperature is below 128° F or above 24O° F, during heavy brake application, at closed throttle,
during heavy or wide open throttle acceleration, during quick tip-ins or tip-outs, or when actual engine speed is below a certain value at lower
vacuums. During these modes, no current flows through the solenoid.
Hydraulics With Converter Clutch Unlocked, 1988 Thunderbird And 1988-1989 Mustang
