G56 Transmission Specs & Ratios
The Mercedes Benz G56 is a powerful manual 6-speed gearbox used in a variety of HD Ram pickups and mid-size commercial vehicles. There is often confusion about when the G56 was introduced on the Ram platform. The G56 was put into service during the 2005 production year together with the NV5600 and eventually replaced the New Venture unit. Before 2005 the transmission was not a selectable option; the microphones received an NV5600 or G5600 or G56. The G56 aluminum housing is much lighter than the NV5600 and has a higher input torque. There are many reliability problems with the G56 in cases where engine performance is increased by replacement accessories. Enclosures and gears are known for their cracks, mainly due to bending under high loads. The G56 also has a relatively short oversteer ratio, resulting in a slightly higher engine speed at cruising speed. Moreover, the gearbox operates reliably and smoothly at the expected input torque.
Which oil for the Merceded G56?
The choice of lubricant has been the subject of much controversy, with many owners and industry experts argue that using ATF+4 to lubricate the transmission, as recommended by Chrysler, can lead to premature failure. Mercedes-Benz recommends a thicker transmission oil of 75W or 90W in its G56-equipped trucks. The question is whether converting to 75W/90W transmission oil will make a difference, but many owners choose this solution. For model year 2007.5, a tooth was removed from the input shaft, resulting in a translation change for the Cummins 6.7L version. Equipped with 6.7 L applications, the torque was derived to 610 lb-ft for the 2007.5 to 2012 model years and to 660 lb/Ft. For 2013 for the current model years. The Cummins turbo diesel is now available with an automatic transmission up to 900 lb/ft.
What can go wrong with the G-56?
The G56 is an excellent transmission and is lighter than its predecessor NV5600, the G56 is manufactured in Brazil and enjoys a great reputation.
The NV5600 heats up and burns, but the G56 breaks down. They are made for work trucks, they work hard and have to work hard, which is why they are made, but if you have a powerful engine and a heavy load, that energy must go somewhere. If the clutch does not slip and the rear wheels do not slip, the transmission breaks, and that is what we see. It will not burn or wear out; it will just break. In recent years we have regenerated many G56’s, and in all situations, the gearbox or gears are broken. We also saw that the gearboxes broke due to too much torque, so the engine runs the transmission. We have also seen rear supports that have been rotated by the crossbar, but here at High Gear we have solutions.
The manufacturer recommends ATF-4 (4/4) oil, but here at High Gear we use Delvac Mobil 50 and we get excellent results.
We recommend that you fill up to the spill (until it passes the filling opening, about 4 liters) and then pour an additional 2 liters into the hole in the housing (where the housing is located).
We used Delvac Mobil 50 weight oil from the Florida Keys to Toronto with excellent results. Call us if you have any questions.