General Motors 5L40E

Transmission general data

The 5-speed automatic transmission 5L40E was designed in 1999 jointly with the 4-speed 4L40E. It became widely used on RWD vehicles of GM and BMW with engines from 2.0 up to 3.6 liters (340 Nm) since 2000. This transmission was especially preferred by BMW (from BMW 3 (4L40E) to BMW 5 and Х5 (5L40E). Then these transmissions were commonly used across the globe: the USA (BMW, Opel, ...), China and Australia (Saturn, Cadillac etc.) and for Land Rover and Cadillac in the UK. The 5L40E transmission is designed on structural basis of 4L60E tested on American roads and produced on GM plant in Strasbourg, France.

Technical issues and repair guidelines

One of typical problems for the 5L40E during the first years of production is the radiator temperature regulator failure resulting in problems with the torque converter. The torque converter is handed in for repair during the reassembly. Experts assume that the torque converter cannot endure frequent forced switch-on of the clutch lock-up, its friction lining burns faster than other friction elements leading to dirt accumulation in the pump, valve body and solenoids and consequently all other transmission units.

Friction elements of the pack (Direct) (one-sided with internal and external teeth) burn twice as often as the Forward pack. Cover plates of the Direct pack are commonly replaced together with clutches. O.Dr.; Reverse frictions also get burnt quite often.The tight fit of rubber covered pistons is an unpleasant peculiarity of 5L40E repair, caused by features of the rotor type oil pump with its huge pressure potential.The kit of rubber-covered pistons is usually ordered for the overhaul.

PMW solenoids rapidly wear out instead of the valve body channels and plungers.Problems with solenoids which exhausted their resource and dirty valve body lead to insufficient pressure in the line that may result in ATF overheating because of slipping frictions, vibrations caused by uneven wear-out and cranking by bushes.

The kit of bushings is a typical order for repair of the 5L40E, which went through a long-time oil starvation at high speeds. One of the most common problems is the pump stator channel wear-out leading to the oil pressure decrease. The pump stator valve is also replaced quite often.

The valve body primarily suffers because of modes settings, when PWM-solenoids open the channel for ATF not immediately on full cross-section, but step-by-step opening and closing it. Movement acceleration of a hot pulp occurs in the narrowest area because of ATF and dirt. The torque converter transmits dirt to the transmission by means of worn-out clutch of the valve lock-up. Solenoids and the oil pump reach the end of their service life earlier than the valve body. It is a trigger for car owners to change oil and solenoids avoiding the valve body wear-out.

The 5L40E is considered to be a robust and reliable transmission, when preserving it from heavy oil contamination with friction dust, which wears transmission components.