The T5 transmission has the honor of having the longest production run than any other American made manual transmission. The transmission was used by numerous automobile manufacturers in nearly a hundred different applications. Jeep too would introduce the T5 to their product line in the early 1980’s. The introduction of a 5 speed transmission into a Jeep was a welcome sight for many; however, for some the strength and dependability still lied in question.
AMC introduced the “T5” five speed transmissions and its 4 speed counterpart the “T4” into the CJ jeeps in 1982. The T5 transmission evolved from Borg Warners lighter duty SR4 transmission that was previously used in both Jeeps and Fords. The T5 introduced tapered roller bearings on the input shafts and output shafts, an improved design over the roller bearing design of the SR4. The transmission was offered behind the AMC 150 (2.5L) Inline 4 cyl. and the AMC 258 Inline 6 cyl (4.2L). The T5 used all helically cut fully synchronized in all gears, with all helically cut gears. The T5 was a top loaded and top shifted transmission. The shifter was located in a removable rear tailhousing section.
The T5 transmission case is 9.25 " long in addition to its 6" tailhousing/shifter assembly for a total overall length of 15.25". The T5 case is cast aluminum as is the top cover. The top cover is retained by eleven bolts to the main case. The transmission typically has a casting # of “13-51” or “13-52”.
The T5 had a 23 spline output shaft connecting it to the Dana 300 transfer case in the CJ models. There was also a small production of 1984 Cherokees with the NP207. The transmission input shaft had a 7-1/2" stick out length from the front of the transmission. The input sh
aft was offered with two different spline count options. Input shafts used with the 258 inline 6 engines had 1-1/8" x 10 splines. The AMC four cylinders had transmissions with a 1” 14 spline input shaft. The pilot tips for both input shafts were .59”.
The T5 transmission was Jeeps first venture into a 5 speed transmission. The T5 does not have a compound low gear but does have all around good gearing ratios of: 1st gear 4.03:1 2nd gear 2.37:1, 3rd Gear 1.50:1 4th Gear 1.00:1 5th Gear .86:1 Reverse 3.76:1
The strength of the T5 has often been debated. It was clearly a better transmission than its predecessor the SR4. It does however have its limits and careful consideration is advised in deciding your best plan of action when contemplating a V8 conversion. Advance Adapters does offer a multi drilled bellhousing to mate a Chevy V8 to the T5. The 712548 bellhousing allows for the retention of the factory clutch pedal configuration. Since we use the same bell housing for Chevy to Ford applications, this bellhousing will also bolt up to popular heavy duty truck transmissions like the Ford T18 and NP435. Customers who choose to use this bellhousing for the T5 have the opportunity to upgrade to other transmissions.
The Borg Warner manufactured SR4 was a four-speed transmission primarily used in 1980 to 1982 Jeep CJ models. The transmission was found behind the 151 Iron Duke 4cyl and the AMC 258 Inline 6. The transmission is considered somewhat light duty, yet the transmission often finds its way behind Chevy V8s do to the Iron Dukes familiar Chevy V8 bolt Pattern. Like many transmissions, the SR4 was not originally designed exclusively for the JEEP. The original SR4 was used in 76-79 mustangs. The SR4 transmission the transmission was commonly referred to as the “RAD” and was ran behind Ford 2.3 4cyl and the Ford 302 V8. The top cover of the SR4 actually even has the Ford Blue Oval Logo stamped on it.(see photo) The SR4 is a top loaded transmission features full synchronization in all forward gear. 1st and 2nd synchros are larger than 3rd and 4th. The SR4 gears are all helically cut. The SR4 consists of an internal single-rail shift linkage. Ball bearings are located on front input shaft and rear main output shaft. The cluster gear consists of a shaft sliding through it and is supported by loose needle bearings.
The SR4 transmission consists of two sections. The aluminum front case is 9-1/4" long. It also features an aluminum top cover retained by eleven bolts. The rear of the SR4 consists of 5.9” rear tailhousing making an overall length 15.25”. The transmission height is 14” and weighs 61lbs. The shifter does not come out of main section of the transmission; rather it is located in the rear tailhousing section of the transmission. The SR4 and JEEP T4 are commonly confused and misidentified as their dimensions are near exact. Both the SR4 and T4 have a unique "S" curve bend on the handle differentiating them from the 45 degree angle of the T176 shifter . Beside overall dimensions, the SR4 can further be identified by casting #'s of “13-32” and “13-40”. The “13-32” were typically found on AMC 258 inline 6 engines while the “13-40” casting # were for Iron Duke four-cylinder Jeeps.
The Jeep SR4 has a 23 spline rear output shaft for mating to the Dana 300 transfer case. The transmission input shaft has a 7-1/2" input shaft stickout with 1-1/8" x 10 splines. The SR4 does not have a compound low gear but does have all around good gearing. The SR4 was available with two different gear options. The gear ratios were differentiated based on the engine mated to the transmission. The gearing options were:
The strength of the SR4 has often been debated. It is usually a one sided debate as the SR4 clearly is not known for handling heavy V8 horsepower. So what explains the high amount of Chevy V8’s behind the SR4? This can easily be explained by the commonality of the Iron Duke Engine bolt pattern. Since the Iron Duke shares the same 90 degree bolt pattern as the Chevy V8, the Chevy V8 will bolt up to the factory Iron Duke bellhousing. The conversion does require the smaller GM flywheel, mini high torque starter, and modifications to the bellhousing. If replacing the 258 inline 6 engines, Advance Adapters does offer a multi drilled bellhousing to mate to the SR4. The 712548 bellhousing allows for the retention of the factory clutch pedal configuration. Since we use the same bell housing for Chevy to Ford applications, customers who choose to use this bellhousing for the SR4 have the opportunity to upgrade to other transmissions. This bellhousing will also bolt up to popular heavy duty truck transmissions like the Ford T18 and NP435. The SR4 was only used for a short 3 year period. The T176, T4 and T5 would eventually replace the SR4 transmission entirely by 1984.