General Motors has produced great overdrive automatic transmissions, and the two transmissions you will hear a lot about are the 700R4 and the 4L60. These are really the same transmission, but were renamed over the years, and are considered a terrific and well-made transmission.
Key Components to the700R4 and 4L60
This transmission is positioned longitudinally and has an automatic four-speed. This family of transmissions uses a two shift solenoid. By activating and deactivating these solenoids in a specific pattern, you can get four distinct gear ratios. The transmission is constructed from cast aluminum alloy. It also utilizes a lockup torque converter. A square oil pan is also standard with this transmission type. Many performance vehicles use this transmission.
When the 700R4 came out in 1982, there was pressure to increase the fuel economy of new vehicles. The transmission was used in rear-wheel drive cars and trucks. Truck transmissions use a slightly thicker case. The biggest feature of the 700R4 was the thirty percent overdrive. Changes and improvements were made over the years the 700R4 was produced (1982 – 1990). Early versions of this transmission had a cooling circuit that used ¼ “pipe fittings, while later versions were changed to an O-ring and pinned flare design.
The 700R4 uses a 4 pin electrical connector and a TV cable. This TV Cable was very sensitive to adjustments and would fail if not adjusted properly. The TV cable is not used on the 4L60-E. The older versions also had a tendency to have seal and gasket leakage. This issue was fixed as improvements were made over the years.
The 700R4 had twenty-seven splines on the input shaft. When this transmission was renamed as the 4L60 in 1990, some small changes had been made, such as increasing the splines on the input shaft to thirty. The name 4L60 stands for 4-speeds, longitudinally placed, and 6000 pounds gross vehicle weight. By 1998 the 4L60-E was released broadly by GM in both 2 and 4 wheel drive vehicles.
In 1993 the biggest change occurred, and the 4L60 changed to the 4L60-E. The hydraulic shifting system was changed over to an electronic system. The transmission’s transmitting core mechanically remained the same, but the clutch/band actuation systems and valve body were now controlled electronically.
The primary feedback sensor was also changed at this time to a Vehicle Speed Sensor, or VSS. This was and improvement and actually a simplification of the transmission design. The 4L60-E also underwent some changes over time. One improvement was the installation of removable bell housing. The tailhousing/adapter pattern was also modified to a rear, six bolt hex pattern.
Either one of these makes a great conversion transmission, and is adaptable for most Jeeps. Many Jeep owners switch to this transmission and benefit from a 25-30% drop in fuel consumption.
The 700R4 and 4L60 transmissions are some of the finest that GM has ever made.