NV 4500 Manual Trans

NV4500 Introduction

Fig. 1:

The NV4500 is a five-speed, constant mesh manual transmission. All gear ranges including reverse are synchronized. Fifth gear is an overdrive range with a ratio of 0.75:1. The transmission has a cast iron gear case and aluminum shift cover.
Two versions of the NV4500 are used. A standard duty version is used for 5.2L and 5.9L applications and a heavy duty version for V10 and Cummins diesel applications. Main differences are the larger diameter input shaft, output shaft, and mainshaft fifth gear in the heavy duty model.
The NV4500 is a top loader style transmission. The shift lever is located in a shifter tower which is bolted to the shift cover and operates the shift forks and rails directly. The shift forks and rails are all located within the aluminum cover which is bolted to the top of the gear case.
Tapered roller bearings support the drive gear, mainshaft and countershaft in the gear case. Pilot roller bearings in the drive gear support the forward end of the mainshaft. The mainshaft gears are all supported on caged type roller bearings. Drive gear thrust reaction is controlled by a needle type thrust bearing. The bearing is located at the forward end of the mainshaft.