NV4500 Service Manual with full coverage of Disassembly, Inspection, Exploded Views, Parts Guide, Assembly, Cover Service, Torque King® Installation, Service Notes, Specifications, FAQ, Tech Articles, and more!
|Current Production NV4500 Gear Ratios||Getrag G360 Gear Ratios|
Current Production NV4500 Specifications*:
|Main Case||Cast iron|
|Shift Cover||Aluminum alloy|
|Gear Bearing||Caged roller|
|Main Shaft Pilot||Straight roller|
|Lubricant||SyntorqLT Synthetic 75w85w gear lubricant|
|Shift Pattern||Same as Getrag|
|Support Bearing||Timken tapered roller|
|Input Thrust||Flat thrust bearing assembly|
|Dry Weight||195 pounds|
|Rated Gross Vehicle Weight||HD: 16,000 pounds, LD: 15,000 pounds|
|Rated Gross Combined Weight||HD: 21,000 pounds, LD: 19,000 pounds|
|Torque Rating||HD: 460 lb.-ft. LD: 410 lb.-ft|
|Oil Capacity Transmission Only||4 quarts, but we recommend 4.5 quarts|
|Oil Capacity including TC adapter||5 quarts (when replacing Getrag)|
|PTO||Standard 6 bolt on each side|
|Dodge HD Input Shaft||1 1/4" 10 spline with .750" pilot tip diameter|
|Dodge LD Input Shaft||1 1/8" 10 spline with .750" pilot tip diameter|
|GM Input Shaft||1 1/8" 10 spline with .590" pilot tip diameter|
|Dodge 4x4 Output Shaft||HD: 29 spline, LD: 23 spline|
|Dodge 4x2 Output Shaft||HD: 31 spline, LD: 30 spline|
|GM 4x4 Output Shaft||32 spline|
|Bellhousing Bolt Pattern||top 10.078", bottom 9.738" Height 6.043", 5.600" index|
|Bellhousing Bolt Pattern 1993-95 GM||top 10.078", bottom 10.394" Height 4.685" 5.125" index|
*NV4500HD models are used with Cummins Diesel & V10. NV4500LD models are used for all other applications.
The NV4500 series transmissions have undergone many minor and major design changes since 1992. The minor changes, while important for durability and shifting ease, are not easily identifiable to the layman trying to determine the features of a particular transmission. The following list shows the major changes we have identified. To precisely identify a particular transmission by part number, get the numbers off the build tag on the left PTO cover and the decals on top of the top cover.
"Losing" fifth gear can happen to any stock NV4500, but it is most commonly experienced with 1994-1998 Dodge turbo-diesel trucks used for heavy trailer towing and/or equipped with enhanced horsepower Cummins engines. The problem is less frequent on 1999 and newer Dodge turbo-diesel trucks with the revised factory 5th gear nut. While the nut is often blamed, the part failing is really the factory mainshaft.
For more information on fifth gear failures and cures, go to Tech Article
There can be many causes of this phenomena with the most common being wrong or degraded lubricant. NV4500 series transmissions were specifically designed for use with Castrol Syntorq LT® GL4 rated synthetic gear lubricant. Most other gear lubricants will damage the carbon fiber surfaces on the synchronizer rings.
Another problem related to shifting difficulty is failure of the pilot bearing. The stock pilot bearings used by Dodge and GM are needle bearings. Over time, these bearings have a tendency to run out of lubricant and disintegrate. This allows the front of the input shaft and clutch disc to "float" about. Erratic clutch performance and misalignment of the internal transmission components result. This combination often causes shifting problems.
New and newly rebuilt NV4500 transmissions may shift hard until the synchronizers wear in. At the other end of the spectrum, well used, high mileage transmissions with worn bearings and/or thrustwashers may shift hard or pop out of gear due to excessive mainshaft endplay.
Rebuilt transmissions with brass synchronizer rings often are hard to shift. Sometimes, changing the oil may help, however, in most cases you either have to install genuine New Venture rings or live with it.
A clutch that does not fully disengage will make it hard or impossible to shift the transmission particularly into fist and reverse. Installing a new clutch usually is the trigger for this problem, but the clutch itself is almost never the culprit. A new clutch will require pretty close to the full travel of the clutch pedal to disengage. Sometimes it is a simple as removing an extra floor mat that the pedal bottoms against. Any internal wear in the hydraulic system or external wear in the under dash components, clutch fork, and/or fork pivot ball can cause inadequate disengagement. The solution is to replace or repair the guilty parts.
Castrol Syntorq LT® 75w85w GL-4 rated, low temperature, synthetic gear lubricant is the only factory approved lubricant for NV4500 series transmissions. Some other lubricant manufacturers such as Amsoil may have products that are compatible. However, we have yet to see any other lubricant match the specifications of Syntorq LT®.
Castrol Syntorq LT® is available in quart bottles from Dodge dealers (p/n 4874459) and GM dealers (p/n 12346190). Castrol distributors offer factory sealed 16 gallon drums, plus some repackage the oil in 5 gallon pails.
It is relatively easy to increase the power output of late model Diesel engines. While the NV4500 is a pretty good transmission, it is not capable of taking extreme increases in horsepower on a sustained basis without sacrificing longevity.
The factory torque rating for NV4500HD transmissions is 460 ft/lbs. (About 235 hp). The design does seem to be capable of up to 600 ft/lbs with little loss of durability. However, as the horsepower and torque increases beyond 275hp/600ft-lbs torque, the size of the bearings, synchronizers, gears, and splines are no longer adequate. Rarely does a NV4500 fail catastrophically even at double the factory ratings, but the fact is most grossly overloaded 4500’s will not last even 100,000 miles without a rebuild.
Yes, we can eliminate typical fifth gear failures with our Torque King® mainshaft and gear sets, and yes, we can even supply larger input shafts, but there is no practical way to increase the capacity of the other components. Except for competition pulling, stock input shaft breakage with the NV4500 is extremely rare. Mainshaft breakage is even rarer.
When subjected to repeated overloads, accelerated bearing and synchronizer wear will occur. The NV4500 is a 195 pound transmission designed for stock vehicles up to 1 ton and 19,000 lbs Gross Combined Vehicle Weight. If your engine horsepower or towed loads are typical of medium and heavy duty trucks, you should, as a minimum, consider retrofitting a 6 speed transmission such as the 365 pound NV5600. Better yet, would be to buy a 2 ton truck made to take the power/loads you require.