The Novak Guide to the
Tremec T176, T177 & T178 Transmissions
The Tremec T176 transmission was the optional four-speed transmission found in 1980 to 1986 Jeep CJ models. It is a good transmission when well maintained and has often been adapted to V8 and V6 power.
Rated at medium-duty, the T176 is stronger than its compact size may suggest. The T176 is frequently retained in CJ Jeeps when married to typical GM V6 and V8 power.
The T177 and T178 are the J Series versions of this transmission as supplied with the 258 I6, and they feature significantly longer input shafts and bellhousing spacers to compensate for the deeper bulkheads of the FSJ Jeeps. The gearing differs as well. References to the T176 are largely similar to the other two versions. Failures of the T17x are more common in the Jeep trucks as they had greater weight and duty demands.
For the big-gears crowd, it is popularly replaced with the Ford T18 and Ford NP435 transmissions, since they share a similar bellhousing bolt pattern and compact installations.
The T176 is a top loaded, top shifting transmission. The T176 is fully synchronized in the first through fourth gears. All gears are helically cut.
The T176 transmission case is 10-1/4" long or 12.9" long with the Jeep style adapter, and features a cast aluminum top cover that is retained by six bolts and a main case of cast aluminum.
The Jeep T176 has a 23 spline output shaft for connecting to the transfer case input shaft. The transmission has a 7-1/2" input shaft (stick-out length) with 1-1/8" x 10 splines and a neoprene front bearing retainer assembly. The pilot tip is ~19/32" in diameter.
The T176 features a conventional "H" shift pattern, with reverse being towards the passenger and down. Typical casting numbers found on the T176 main case can be C-2604203 or c-2604206. Top cover casting numbers like C-2604208 are common.
Transfer Case Compatibility
The Jeep T176 was factory-married to the Jeep Dana Spicer Model 300 transfer case. The T177 and T178 transmissions were married to the New Process 208 (208J) transfer cases.
Because of clocking rotation differences, the T176 is not compatible with the NP231 transfer case.
Bellhousing Adaptability
GM
Buick V6, Chevrolet Small Block V6 and V8 conversions to the T176 are done with steady frequency and success.
AMC Jeep
As the T150 was married to the Jeep AMC engines, it is OEM compatible with them using the 6-1/2" deep 1976-1986 bellhousing as found behind AMC I6 and V8 engines.
Ford
The T150 has a front bolt pattern is the symmetrical Ford "butterfly" pattern; roughly 8-1/2" wide by 6-5/16" tall. It is sometimes married to Ford V8 power, as discussed here.
Rebuilding the T176
Hypoid gear oil is sulphurized higher than transmission oil and can be mildly corrosive to the non-ferrous alloys used for synchros, bushings and thrust washers in these transmissions.
An 80W-90, API-GL5 or MT-1 rated fluid is very good. Some claim faster shifts from using a 50W engine oil in their transmission and we do not consider this to be contraindicated unless you operate your vehicle in a very warm environment.
The T176 is not difficult to rebuild. Many shadetree mechanics do very outstanding rebuilds if they have access to a press, snap ring pliers and bearing pullers. Many choose to do a full rebuild during the adaptation process, and our instruction guides feature all the details, diagrams, pics and tricks required to do professional level work.
Summary
The T176 arrived in an era when Jeeps needed a stronger four-speed transmission with some street manners. Though it did not feature a compound first gear like the T18 transmission it replaced, it was still useful when paired with the low gear provided by the Jeep Dana 300. All in all, the T176 is seen favorably by Jeep aficinados.
