4L80-E Trans

94-97 4L80-E Transmission

Active Components For Each Gear:

Transmission Designations:

Component Description:

Lubrication Flow:

Planetary Gear Sets:

Planetary Gear Sets
Three planetary gear sets are used in this transmission: 'overdrive', 'reaction' and 'output'.

Each gear set comprises a center or sun gear, an annulus or internal gear, and a planetary carrier assembly which contains the smaller planet gears.

Direct drive in a planetary gear set is obtained when any two parts of a gear set rotate in the same direction at the same speed, thus driving the third component at the same speed. The planetary gears in this case act as wedges to drive the entire gear set as one unit and therefore the output speed of the transmission is the same as the input speed from the torque converter.

Conversely, a planetary gear set reverses the direction of power flow when a carrier assembly is held stationary and power is applied to the sun gear thus causing the planetary gears to act as idler gears to drive the internal gear in the opposite direction.

In first, second and third gears, the 'overdrive' roller clutch retains the 'overdrive' sun gear and carrier assembly together, thereby driving the internal gear at the same speed.

In first gear, the 'output' internal gear drives the 'output' carrier planet gears clockwise, which causes the sun gear to rotate anti~lockwise. As the 'output' sun gear and the 'reaction' sun gear are common, the 'reaction' carrier planet gears rotate clockwise. The 'reaction' carrier, being held stationary by the 'LO' roller clutch, then causes the 'reaction' carrier planet gears to drive the 'reaction' internal gear and the output shaft, ie first gear.

Second gear is obtained when the 'output'/ 'reaction' sun gear is held stationary by the intermediate clutch and therefore when the 'output' carrier planet gears are driven clockwise by the rear internal gear, the planet gears rotate clockwise round the stationary sun gear. The 'output' carrier planet gears drive the 'output' carrier assembly and 'output' shaft clockwise, ie second gear.

Third gear is obtained when the direct clutch is applied; the power flow from the 'overdrive' planet gears and the forward clutch housing is then transferred to both the 'sun' gear and the 'output' internal gear. With the power flow through the 'overdrive' planetary gear set being a direct drive, and with both the sun gear and the internal gears of the 'output' planet gear set driving at converter turbine speed, the 'output' planetary gears act as wedges and drive the 'output' carrier assembly and output shaft together, ie direct drive, third gear.

In fourth gear, the 'overdrive' sun gear is held stationary by the fourth clutch being applied, then the 'overdrive' carrier being driven clockwise, the 'overdrive' planetary gears rotate clockwise also on their axes around the stationary sun gear. This causes the planetary gears to drive the 'overdrive' internal gear clockwise and so an 'overdrive' ratio is obtained through the 'overdrive' planetary gear set.

In reverse gear, the rear brake band is applied to hold the 'reaction' carrier stationary while the direct clutch is applied to supply clockwise power flow to the sun gear. Power flow from the 'overdrive' planetary gear set being a direct drive, the sun gear drives the 'reaction' planetary gears anti~lockwise which drives the 'reaction' internal gear ('output' carrier assembly) anti~lockwise ,ie reverse gear.