Heavy Duty Transmissions

Reprinted from Gears Magazine March 1998 by

Brain Johnston VP, Rockland Standard Gear, Inc.

The Gertag 360

This 5 -speed, cast-iron transmission appears in Dodge trucks with the 5.9 diesel engine, from 1989 through 1993. This design suffered from being under "spec'd" for the motor it was mounted to, and has the dubious distinction of being the most expensive unit to repair of its ear. An overhaul kit sell for $750, a cluster gear for $1,100, and list price for a new unit is $3,875. Most owner of these vehicles opt for installing an NV4500 in its place after fighting durability problems. This unit features helical gearing, with all forward speeds synchronized and in constant mesh.

The NV4500

This is a 5 speed, cast-iron case, top-loading transmission, used by GM and Dodge in their heavy duty pickups. It's a serious truck transmission that uses some innovative designs. The NV4500 is found behind gas and diesel engines, and is produced in tow and four wheel drive configurations. Using helical gearing with all speed gears in constant mesh and all speeds synchronized, this transmission will handle 450 ft-lbs of torque, and vehicles with a combined gross weight of 19,000 pounds. The 4500 uses a dual cone synchronizer for first and second gears, similar to the familiar, world class T5 design. The 1-2 synchronizer also has a set of spring loaded flyweights in the synchro hub that govern shift speeds, to prevent over-revving the motor on a 2-1 downshift. The 4500 weighs in at 195 pounds dry, and has a lube capacity of 8.5 pints.

The 4500 is a serious truck transmission with a simple, easy to work on design. New Venture has the capability of adding a sixth speed to this design. The ability to have gas and diesel engines geared low enough for serious pulling power and having one or two overdrive gears for fuel efficient cruising is a necessity for today serious truck owners.

Back to NV4500 Conversion page.