Cummins Transmission Guide

Transmission Ratios & Info for Cummins Equipped Ram Pickups

The following ratios and information are specific to transmissions available with the Cummins turbodiesel in Ram pickup truck applications only. Specs may differ for applications beyond this scope.

 

Transmission

Type

Manufacturer

Model Years

1st

2nd

3rd

4th

5th

6th

R

A727 TorqueFlite

3 spd auto

Chrysler

1989 - 1991

2.45 : 1

1.45 : 1

1.00 : 1

n/a

n/a

n/a

2.21 : 1

A518 TorqueFlite

4 spd auto

Chrysler

1991.5 -1993

2.45 : 1

1.45 : 1

1.00 : 1

0.69 : 1

n/a

n/a

2.35 : 1

Getrag G360

5 spd manual

Getrag

1989 - 1993

5.53 : 1

3.02 : 1

1.60 : 1

1.00 : 1

0.77 : 1

n/a

5.03 : 1

47RH/47RE*

4 spd auto

Chrysler

1994 - 2002

2.45 : 1

1.45 : 1

1.00 : 1

0.69 : 1

n/a

n/a

2.21 : 1

48RE

4 spd auto

Chrysler

2003 - 2007

2.45 : 1

1.45 : 1

1.00 : 1

0.69 : 1

n/a

n/a

2.21 : 1

NV4500

5 spd manual

New Venture

1994 - 2005

5.61 : 1

3.04 : 1

1.67 : 1

1.00 : 1

0.75 : 1

n/a

5.61/5.04**

NV5600

6 spd manual

New Venture

1998 - 2005

5.63 : 1

3.38 : 1

2.04 : 1

1.39 : 1

1.00 : 1

0.73 : 1

5.63 : 1

68RFE

6 spd auto

Chrysler

2007.5 - current

3.23 : 1

1.84 : 1

1.41 : 1

1.00 : 1

0.82 : 1

0.63 : 1

4.44 : 1

G56

 

6 spd manual

 

Mercedes Benz

 

2005 - 2007

6.29 : 1

3.48 : 1

2.10 : 1

1.38 : 1

1.00 : 1

0.79 : 1

6.29 : 1

2007.5 - current

5.94 : 1

3.28 : 1

1.98 : 1

1.31 : 1

1.00 : 1

0.74 : 1

5.42 : 1

AS69RC***

6 spd auto

Aisin

2013 - current

3.75 : 1

2.00 : 1

1.34 : 1

1.00 : 1

0.77 : 1

0.63 : 1

3.54 : 1

* "RH" model was hydraulically controlled while the later "RE" was controlled electronically
** 1998+ model year NV4500 transmissions carried a taller 5.04 : 1 reverse ratio compared to the earlier versions 5.61 : 1
*** Aisin AS69RC is available exclusively on Ram 3500 models with the High Output (H.O.) 6.7L Cummins

 

Chrysler Automatic Transmission Name Convention

Applicable to 1994+ Chrysler transmissions

Chrysler transmission name convention

Forward gears - the number of forward speeds the transmission has.

Strength designation - Chrysler's strength designation is an arbitrary number representing the transmission's strength on a scale of 1 through 9; the higher the number, the higher the transmission's input capacity. This number is not a direct representation of the transmission's maximum input torque capacity. A strength designation of "8", for example, does not correspond to a max input torque capacity of 800 lb-ft.

Application - all Chrysler transmissions mated to the Cummins turbodiesel will have an "R" in the application designation, which stands for "rear wheel drive".

Control type - An "H" in the control type corresponds to a hydraulically controlled transmission, an "E" for an electronically controlled transmission, and "FE" stands for fully electronic.

 

NV4500 Lugging, 5th Gear Failure

The NV4500 5 speed manual transmission was a popular choice for the 1994 to 2005 Cummins. It's relatively rugged, smooth shifting, and with a clutch upgrade has proved reliable in moderately high performance engines. The gearbox's Achilles heel is the loss of 5th gear, which is caused by the 5th gear retaining lock-nut backing off the threads and rendering it impossible for the operator to select overdrive. Over the years, the cause of this problem has been connected with the act of continuously lugging the transmission in 5th gear as opposed to selecting a lower gear. There are numerous repairs and aftermarket solutions available that prevent the recurrence of this problem, but it can generally be prevented by avoiding low speed, high load operation in 5th gear. This is especially important while towing - rather than allow the engine to lug in overdrive, consider using 4th gear. While the Cummins performs exceptionally well at low engine speeds, you'll put less stress on your transmission by trading higher engine speeds for less load through the drivetrain.