QU10078 1992-1996 NV4500 Countershaft Cluster Gear

QU10078 One Piece NV4500 Countershaft Assembly for 1992-1996 with 5.61:1 First and Reverse Gear Ratios QU10078 is a quality reproduction part that fits 1992-1996 Dodge and 1995-1996 GM New Venture NV4500 5 Speed Manual Transmissions. Front drive gear has 38 teeth, and the 3rd gear has 30 teeth. This shaft can be identified by the gap between the end of the reverse gear drive teeth and the rear bearing seat. Imported.

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Dan the Gear Man® Tech Notes:
GM N4500
22 Tooth Input Shafts
Specs
Matching Gear Part Numbers
Causes of Gear Tooth Failure
Facts
Special Tools
Matching Parts
Lubricants, Sealants, Threadlockers
Applications
Product Video: Three Types of NV4500 Countershafts

Tech Note 1: GM NV4500
QU10078 is a one piece Countershaft that replaces 1995-1996 OE countershaft QU10044 and 1992-1995 QU10090 Modular Countershaft in 1992-1996 Dodge and 1995-1996 GM NV4500 Transmissions with 5.61:1 1st and reverse gear ratios. It can NOT be used to directly replace QU10090 Modular Countershaft in 1992-1994 GM transmissions with 6.34 1st and reverse gear ratios due to different gear tooth counts. To use QU10078 in a 1992-1994 GM transmission, you MUST also change the input gear, mainshaft 3rd gear, and both 5th gears. To use QU10078 in a 1992-1994 GM NV4500, consult the chart below:

Tech Note 2: 22 Tooth Input Shafts
Six different 22 tooth input shafts match QU10078 Countershaft depending upon the year, make and model.

Tech Note 3: Specs
QU10078 is approximately 15" Long. The length of the 1st and Reverse gear drive teeth is 4.5". The groove at the back of the countershaft for the 5th gear clutch is over 0.100" wide. QU10078 will fit any 1992-1996 NV4500 transmission case. Countershaft End-Play should be set at 0.002"-0.006". The Gear Tooth Count is listed in the chart below:

Tech Note 4: Matching Gear Part Numbers
Matching Mainshaft and Countershaft Gear Part Numbers for QU10078 Countershaft are:

Tech Note 5: Causes of Gear Tooth Failure
Typically, Countershaft gear tooth failures occur from one of three causes: low or improper oil, clutch pilot bearing failures (which cause misalignment of the input shaft), and excessive horsepower/torque (over 275hp/600 Lb-Ft of torque). Broken 3rd gear teeth are almost always caused by exceeding the demonstrated 600 Lb.Ft input strength limit of the NV4500.

There are claims that cryogenically treating NV4500 gears will increase gear strength as much as 30%. Unfortunately, there does not seem to be any peer-reviewed documentary evidence to support those claims. Cryogenically treating gears is primarily a cold-hardening process that changes the molecular structure of steel to decrease wear while retaining or increasing hardness. If properly done, it is probable the cryogenic treatment process does slightly increase the impact and fatigue resistance of NV4500 gears, but not enough to significantly increase the ability of an NV4500 transmission to reliably handle more than 600 Lb.-Ft. of input torque especially considering the maximum factory torque rating of the NV4500HD transmission is only 460 Lb.-Ft..

Tech Note 6: Facts
Early (1992-1996) and Late (1997-2007) NV4500 Countershafts are not interchangeable! When first introduced, the NV4500 Transmission had a dual-plane reverse where the power transfer path from the counter shaft to the mainshaft reverse gear is offset. The front half of the 2-3/4" long reverse idler gear engages the countershaft, while the rear half drives the mainshaft reverse gear. Since there are no teeth on the counter shaft below the mainshaft reverse gear, that gear can be larger diameter and have more teeth (39). The 1992-1996 transmissions have a 6.34:1 reverse for 1992-1994 GM and 5.61:1 reverse for all Dodge and 1996 GM.

Effective with the 1997 model year, New Venture NV4500's use a single-plane reverse where the power transfer path from the countershaft to the mainshaft is inline. The full working width of the narrow, 1-1/2" wide reverse idler gear is inline with both the countershaft gear teeth and mainshaft reverse gear teeth. Since the countershaft drive teeth are now located directly under the mainshaft reverse gear, the mainshaft reverse gear diameter had to be reduced to the point it now has only 35 teeth. Less teeth means less gear reduction. All 1997 model year and newer NV4500 transmissions have a 5.04:1 Reverse.

The difference in the transmission case reverse idler gear pocket and mounting boss for the single and dual plan reverse means the countershaft, mainshaft reverse gear, reverse idler gear, and reverse idler shaft are NOT interchangeable between early and late cases

Tech Note 7: Special Tools
Need Torque Specs or Rebuild procedures? Order my 116 page, full color illustrated TM1003 NV4500 Rebuild Manual.

You will need some special tools to correctly service your NV4500 Transmission. The chart below lists our current NV4500 Special Tools for popular models.

Tech Note 8: Matching Parts
QU10140 Sealing Cap, Main Case Countershaft Front Bearing Bore
QK1102 Lock Ring Kit
QK1110 Thrust Washer Locating Pin Set
QU10141 Countershaft 5th Gear Bearing
QU10142 Timken High Performance Countershaft Front Bearing
QU10143 Timken High Performance Countershaft Front Bearing Cup
QU10144 Timken High Performance Countershaft Rear Bearing
QU10145 Timken High Performance Countershaft Rear Bearing Cup
QA10008 Countershaft Shim Kit
QU10008B Basic Countershaft Shim Kit
QK1010 Complete Small Parts Kit
QU10221 Basic Small Parts Kit
QU10031 OEM New Venture 5th Gear Clutch
QU10202 5th Gear Clutch
QU10304 Countershaft 5th Gear Thrustwasher
QU10033 Reverse Idler Gear
QU90020 NV4500 Manual Transmission Oil
TM1003 NV4500 Shop Manual
VSG1003DVD NV4500 Overhaul Video
QT1802 Countershaft Front Bearing Cup Installer
QT2004 Countershaft Front Bearing Installer
QT2005 Counter Shaft Rear Bearing Installer
QT2006 Countershaft Support
For Gearing, see Tech Notes 1, 3, and 4

Tech Note 9: Lubricants, Sealants, Threadlockers
Early production NV4500 Transmissions used an anaerobic sealant (QU90003) to seal between the main case and input bearing retainer, top cover, and rear housing. Mid-production units used anaerobic sealant just on the input retainer and RTV for everything else. Later production transmissions used black RTV Sealant (QU90006 or QU90005) for everything. Either type of sealant works fine (except the PTO covers ALWAYS should be sealed with RTV), but I prefer RTV for all components. Regardless of which sealant you use, make sure excess sealant does not block the lube access hole at the top of input retainer.

Applications:
Dodge: 1992, 1993, 1994, 1995, 1996
GM: 1995, 1996

Video: 3 Types of NV4500 Countershafts