by Skip Shelton
New car engine with red border image from Raxxillion from Fotolia.com
The 4L60 was manufactured by General Motor’s Corporation and was available from 1990 to 1992. The 4L60 was the first automatic overdrive transmission designed specifically for high-performance rear-wheel applications. Available for just three years, the 4L60 transmission was installed in the GM truck line, Pontiac Firebird, Chevrolet Camaro, and some Corvette applications.
The 4L60 designation, while the same for the 4L60 and 4L60E represents the fact that the transmissions are four-speed, longitudinally positioned. The engine is capable of supporting a gross vehicle weight rating (GVWR) of 6,000 pounds. The 4L60E transmission has proven to be stronger than the original 4L60 and fits in applications up to 8,600 pounds. GVWR.
The “E” designation refers to the electronic shift controlled variation found in the 4L60E transmission design. Electronic shift control is managed by the vehicle’s on-board computer system. Shift points are based on rpm, throttle ranges, and a variety of conditions.
The rear output housing is configured in a six-bolt pattern on late-model 4L60E transmissions. The 4L60 transmission is configured with a four-bolt pattern. However, the bolt pattern is not a guaranteed distinction, as early 4L60E transmissions, manufactured between 1992 and 1997, also have a four-bolt pattern.
A significant improvement to the 4L60 transmission is the fact that the 4L60E transmission has a removable hood, allowing greater access to transmission parts.
The E transmission designation may be dropped from more recently produced models of the 4L60E transmission as all transmissions are now electronically controlled. The date of manufacture and the rear output housings are the key identifiers for the first 4L60 transmission and 4L60E transmissions that do not indicate the E designation.