4L60 & 4L60e Transmission Differencesby Skip Shelton
The 4L60 was manufactured by General Motor's Corporation and was available from 1990 to 1992. The 4L60 was the first automatic overdrive transmission specifically designed for rear-wheel high performance applications. Available for just three years, the 4L60 transmission was installed in the GM truck line, the Pontiac Firebird, Chevrolet Camaro and in some Corvette applications.
The 4L60 designation, while the same for the 4L60 and 4L60E represents the fact the transmissions are four gears, Longitudinally positioned, The engine is capable of supporting a 6,000-lb Gross Vehicle Weight Rating (GVWR). The 4L60E transmission has proven to be stronger than then original 4L60 and is installed in applications up to 8,600-lb. GVWR.
The "E" designation refers to the electronic shift controlled variation found in the 4L60E transmission design. Electronic shift control is handled by the vehicles on-board computer system. Shift points are based on rpm, throttle ranges and a variety of conditions.
The rear output housing is configured with a six-bolt pattern in late model 4L60E transmissions. The 4L60 transmission is configured with a four-bolt pattern. The bolt pattern is not a guaranteed distinction, however, as early 4L60E transmissions, manufactured from 1992 through 1997, also have a four-bolt pattern.
A significant upgrade from the 4L60 transmission is the fact the 4L60E transmission has a removable bellhousing, allowing greater access to the transmission parts.
The E transmission designation may be removed from more recently produced models of the 4L60E transmission, since all the transmissions are now electronically controlled. Manufacture date and rear output housings are the key identifiers of the early 4L60 transmission and the 4L60E transmissions not indicating the E designation.
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