Borg-Warner T18 Transmission
The T18 transmission was designed as a replacement for the already successful T98. The transmission was used by numerous automobile manufacturers including Ford, International Harvester, and Jeep.Although the T98 was Jeeps first granny low transmission, it was the Jeep T18 that reached the American masses.The T18 introduced the idyllic attributes that jeep would be synonymous with: strength, low gearing, and dependability.
Jeep incorporated the T18 into their product line in 1966. The T18 transmission offered some benefits over the T98.Both were excellent transmissions; however, the T98 was more susceptible to wear since the bearings and lubrication system were not as efficient. The T18 also provided twice the bearing support on the cluster shaft than that of the T98.
The cast iron T18 transmission case measures 11.87" in length, 17.45" in height, and weighs approximately 145lbs. The Jeep T18 case has a front pattern that is 8.50" across the top, 2.75" from the top to bottom hole on the driver's side and 4.62" top to bottom on the passenger side of the transmission. Jeep CJ 1977-79 used the Ford butterfly pattern and the input shaft is 7" as the pilot bushing is further inside the crankshaft, with our special pilot bearing AA716156 a Ford shaft can be used, the diameter is the same.
The PTO port is located on the driver's side of the transmission for both Ford and Jeep.
Ford T18's have a front bolt pattern of 8.5" wide x 6.3125" tall, known as a butterfly pattern and is compatible with AMC/Jeep bellhousings that utilized the T150/T176 transmissions as well as T18 Jeep transmissions 77-79 CJ as well as 77 and later full size Jeeps. All Ford T18's are 6.32 to 1 in granny 1st gear. The input gear stick out length is 6.50".
The rear of the Jeep T18 was typically a 1-3/8" x 6 spline output shaft for mounting to the input gear of the Dana 18/20 transfer case. The transmission was connected to the Dana 18/20 via a 1" thick cast iron adapter plate held in place by 6 bolts.
The Ford T18 will require AA adapter 50-7201 to connect to a model 18 or 20 Dana/Spicer transfer case, the Ford case has a 4 bolt pattern, this kit comes with the special pilot bushing AA716156 as well as all pieces required to bolt the T18 to a model 18/20. We offer other adapter kits for all the different transfer cases.
There was also an odd T18 combination used in Jeep trucks.T18 was used in 1980-1982 J-20 pickups where the transmission was mated to a round circular six bolt patterned NP208 transfer case. This version of the T18 utilized a longer 8" tail housing with a 23 spline transmission output shaft.
The T18 was offered with two different shift patterns.The earlier T18s have a reverse up and next to third. Transmissions manufactured after 1978 have reverse down and next to forth gear.The reverse shifter fork was relocated from the drivers' side of the case and into the top cover.The location of the reverse gear lever influences the shape of the transmission case.Earlier transmissions have a significant bulge on the driver side of the case. The later t18 transmissions have a flatter surface on the driver side of the case.
The Jeep T18 was offered with two distinct gear ratio options.These are commonly referred to as the close ratio and the wide ratio. The Granny low close ratio was offered with a 4.02:1 first gear ratio and had overall good gear spread.The close ratio T18 transmissions offer a more road friendly drivability. The wide ratio T18 transmissions offered an impressively low first gear of 6.32:1.This alone makes this transmission desirable and heavily sought after by serious off road enthusiasts.The complete gearing is as follows:
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The gear ratio differences can result in some confusion. The complexity becomes compounded by the variety of transmission input shafts. Jeep used over a dozen different input shaft variations on the T18. When sourcing a transmission from a donor vehicle, the variations in input shafts can cause confusion and frustration. It is very common to see individuals purchase T18 transmissions under the promise of finding a good deal only to find their T18 is unusable for their application. |
We have put together a more detailed technical section on the T18 and T98 conversions. Please review this section for a better explanation on the differences, commonalities, and adaption options for these often misidentified and misunderstood transmissions.
T19:
This transmission looks identical to the Ford T18, and the case length is the same. The 1st gear ratio is 5.11:1 1st; 2nd 3.03:1; 3rd 1.79:1, and 1:1 4th gear ratio. These transmissions were used in Ford pickups 1974-88. The first gear on this transmission is synchronized, which is the biggest advantage over the T18. The adapter kits we manufacture for this transmission require a new main shaft. This shaft looks identical to the Ford T18, except it has a snap ring groove for the 1st gear synchronizer.