AMC and Jeep transmissions

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American Motors Corporation (AMC) and Jeep used a variety of transmissions and transfer cases systems. This article covers all AMC (1954+) and Jeep (1946+) variants thru 1988, as well as legacy designs retained by Chrysler (and several other manufacturers) in later years. This includes:

While AMC had used Chrysler transmissions prior to the buyout, it had never used Chrysler engines. They have, at various times used BOP (Buick, Oldsmobile, Pontiac - GM's "independent" divisions until the 1970s) designed engines. By the end, in 1988, AMC was using only AMC Engines in their vehicles.

Contents

[edit] Early Jeep transmissions

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[edit] Manual

Borg-Warner T84 was used in the military MB & GPW Jeeps.

Borg-Warner T90 Transmission used in Jeeps from 1946 through 1971

[edit] Automatic

[edit] Early AMC transmissions

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[edit] Manual

[edit] Automatic

[edit] Late model transmissions

Transmissions on late model AMC vehicles came with either a 21 spline or 23 spline output shaft.

Transmissions coupled to four-cylinder engines normally use 21 spline output shafts. The 23 spline manual transmission was universal in the Eagle lines and also used later six-cylinder applications.

All Torque-Command automatics used 23 spline output shafts. Early AW4s used 21 and 23 splines.

All transfer cases at the time were available with inputs matching both. As it is far easier to change an input shaft in the transfer case than the output shaft of the transmission, transmission swaps are possible and rather straightforward between the various models and years.

[edit] Manual

  • Borg-Warner T-96 three-speed
  • Borg-Warner T-85 three-speed
  • Borg-Warner T-10 four-speed
  • Borg-Warner T-14 three-speed
  • Borg-Warner HR-1 four-speed synchronized unit used with the 121-4.
  • Borg-Warner SR-4 four-speed synchronized unit used with the AMC 6 cylinder and 304 V8 engines.
  • Borg-Warner T-4 and T-5 four and five speed units used from 1982 onwards.
  • Tremec 150T three-speed
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[edit] Automatic

In 1970, AMC standardized on a variation of the Chrysler developed TorqueFlite transmission they called the Torque-Command.

These transmissions were available in both the Chevy V6 pattern and the AMC late model pattern used on their I6 and V8 engines. The Chevy V6 pattern was used on the AMC 150 I4 and the Iron Duke I4 engines.

[edit] The AW4

The AW4 four speed automatic transmission was selected by AMC for use in the Cherokee (XJ) new inline six-cylinder 4.0 L design. It was manufactured by Aisin-Warner, a member of the Toyota group, in partnership with Borg Warner. It shares many parts with its sister Toyota transmission the Aisin 450-43LE, that is incidentally used in Toyota off-road vehicles.

Gear Ratios for the AW4:

  • 1st: 2.80
  • 2nd: 1.53
  • 3rd: 1.00
  • 4th: .75

The AW4 is also used behind the 2.5 L (150 in³) AMC Straight-4 engine. It has a removable bell housing with a cutout for the crank position sensor. The earlier Jeep AW4 has a 21 spline output shaft. In the 1991 the AW4 was changed to a 23 spline output shaft. (Concurrent with the H.O. engine.)

The AW4 used its own control computer from 1987-1996.

  • 1987-1990 Jeep Cherokee (XJ)
  • 1991-1993.5 Jeep Cherokee (XJ) 4.0 L
  • 1987-1990 Jeep Comanche 2.5 L
  • 1987-1992 Jeep Comanche 4.0 L
  • 1993-1993.5 Jeep Grand Cherokee 4.0 L

[edit] A604 derived/Ultradrive

Four gears, torque rating of 2, Rear wheel drive, Limited Electronics. 42RLE

  • 1st: 2.80
  • 2nd: 1.55
  • 3rd: 1.00
  • 4th: .69

[edit] Jeep and Eagle transfer cases

The transfer case is an auxiliary transmission that connects the front and rear axles. It also commonly provides a selectable secondary gear reduction.

The AMC Eagle used three New Process transfer cases, models 119, 129, and 128.

Jeep Transfer Cases (see below for New Process transfer cases)
Case Offset Spline Ratio Bolt Pattern Years Used
Dana 18 Both Right 6 (10) 1.98:1, 2.42:1, 2.46:1 "Texas" -> 1971
Dana 20 Front Right 6 (10) 2.03:1 "Texas" 1963-1979
Dana 300 Front Right 23 2.62:1 "Round"
(New Process)		 1980-1986
Borg-Warner 13-39 Both Right 10 2.57:1 TH 400 ~1970-1979

[edit] Dana

Spicer/Dana

The Dana 18 has an offset rear output. The Dana 20 can be identified by the center rear output, cast iron tail housing, and deep oil pan. Both the Dana 18 and Dana 20 use the "Texas" bolt pattern with five bolts holding on the transfer case. The Dana 300 uses a round bolt pattern with 23 spline input, an aluminum tail housing, and a nearly flat oil pan.

[edit] 18

This is a gear driven transfer case

There are five variations:

  1. 27 tooth drive gear, 3/4" intermediate shaft and 1.98:1 low
  2. 26 tooth input gear, 3/4" intermediate shaft and 2.42:1 low
  3. 26 tooth input gear, 1-1/8" intermediate shaft and 2.42:1 low
  4. 26 tooth input gear, 1-1/4" intermediate shaft and 2.42:1 low range
  5. 29 tooth input gear, 1-1/4" intermediate shaft and 2.46:1 low, 4" input hole, Dana 20 case

The big hole input is about 4-inches in diameter and the normal input is about 3-inches in diameter.

All Dana 18 cases are cast iron.

The normal input Dana 18s are interchangeable, but the input gear must match the transfer case. The big hole Dana 18 is transmission interchangeable with the Dana 20. All Dana 20 and Dana 18 input gears are 6 spline except ones used with the 10 spline version of the T-14 transmission.

All Dana 18s and Dana 20s use the 5-bolt "Texas" bolt pattern.

All Dana 18s have front and rear outputs offset to the passenger side. Most vehicles built with a Dana 18 have a rear axle that is offset to the right side to accommodate this. Most other transfer cases used in Jeeps have a centered rear output that lines up with the input shaft. The Dana 18 always has gears turning, which makes it noisier then some other transfer cases when in 2wd.

There is also a PTO attachment on the case that can be used to drive equipment that accepts PTO input.

[edit] Warn Overdrive

Developed by Warn Industries, the Dana 18 overdrive unit is now produced by Advance Adapters Inc under the name, Saturn Overdrive.

A unique feature of the Dana 18 is the overdrive that attaches in the PTO port in the back of the system. There is an adapter that allows use of both the overdrive and the PTO attachment, but it is no longer produced.

This overdrive unit has several versions. Differences include whether the shifter attaches to the front or rear of the unit. (See [1]). Its .75:1 overdrive ratio is available in any gear.

[edit] 20

This is a heavy duty gear driven transfer case with a 26 tooth input gear. Like the 18, it is an all cast iron unit. The output for the front driveshaft is on the passenger side and the rear output is in line with the input.

Low range is 2.03:1.

The Dana 20 is generally compatible with the big hole Dana 18. One exception is the version used with the Turbo 400 in full-size Jeep trucks, which used a different spline number on the input gear.

[edit] 300

This is a heavy duty gear driven transfer case with a 23 spline input shaft. The case is cast iron and the tail housing is aluminum. The ID C300-15 is stamped on the case. The output for the front driveshaft is on the passenger side and the rear output in line with the input. Low range is 2.62:1.

The bolt pattern and spline count are the same as many New Process transfer cases, but NP cases have the front output on the driver's side instead of the passenger side. Some fabrication may be necessary on the transfer case or the adapter to clock the transfer case when interchanging since one bolt in the pattern is offset so the transfer case can only attach one way.

One common modification is to add oil paddles to the main shaft to prevent oil starvation of the rear bearing.

The Dana 300 was used in CJs from 1980 to 1986. The 1980 factory original came with a shorter tail housing and a longer rear driveshaft to match. The 300 should fit behind all Torque-Command transmissions.

[edit] Borg Warner 13-39

The Borg-Warner 13-39 transfer case was part of the first system that AMC marketed as Quadra-Trac. It was the first Jeep transfer case to be made of aluminum and to be chain-driven. It may have the casting number 13-39. The output for the front driveshaft and the rear driveshaft is on the passenger side.

A low range of 2.57:1 is an optional unit that bolts to the back of the transfer case.

This was the optional (in lieu of the Dana Model 20) full-time chain drive transfer case that was found behind the AMC TH400 automatic between 1973 and 1979. It was only used with an AMC version of the GM TH-400 automatic transmission with a special long 10 spline output. It is not bolt compatible with any other Jeep transmission.

This unique transfer case had an integrated limited-slip differential that splits power between the front and rear driveshafts. There is a vacuum operated differential lock (the vacuum switch is usually located in the glove compartment) available for use in both high and low range.

There is a Mile Marker 16% overdrive gear and chain set available for the Quadra-Trac that affects high and low range and converts the transfer case to part time operation.

The basic version of the QuadraTrac is the BW 13-05. This transfer case did not have a low range, the optional low range of 2.57 was a bolt-on planetary reduction unit. This unit as an assembly was designated as the BW 13-39.

[edit] New Process/New Venture

In general, cases are identified by a three-digit code. The first digit (1 or 2) determines the number of gear ranges. The second number is a series number that reflects design, and provides a vague idea as to torque handling. If the second number is a one there is no 2wd option, if it is a two there is a two wheel drive option. The third number can be read for differential type: One for locked (no differential), two for open, three for electric locked, four and five for an asymmetrical torque split planetary gear and gear drive, six for an electronic clutch pack, seven for a hydraulic clutch pack (excepting the odd 207), and nine for a viscous coupler.

For example: The 128 and 228 are nearly the same, except for the low range as indicated by the leading 2.

A locked differential allows no difference in speed between the average of the front axle and the rear axle. A viscous differential uses silicone fluid and slotted plates in a method similar to a limited-slip rear end, and provides for some front-rear axle variation. An open differential is the same as in an axle; if one wheel loses traction it spins while the rest stop moving.

These are chain-driven transfer cases and use a 21 spline input with four-cylinder engines and a 23 spline input with six-cylinder and V8 engines. All Eagle applications use 23 spline inputs. The output for the front driveshaft is on the left or driver's side. New versions of the NP231 and NP242 are referred to as NVG or NV, which stands for New Venture Gear.

Jeep/Eagle Transfer Cases -- New Process
119 128 129 147 207 208 219 228 229 231 241 OR 242 247 249
Full-Time High Yes Yes Yes Yes No No Yes Yes Yes No No Yes Yes Yes
High Lock No No No xx Yes Yes Yes No No Yes Yes Yes No No
Low Range No No No No 2.61:1 2.62:1 Yes Yes Yes 2.72:1 4.0:1 2.72:1 2.72:1 2.72:1
2wd No Yes Yes No Yes Yes No Yes Yes Yes Yes Yes No No
Differential Viscous Open Viscous Gyro-Clutch Locked xx Viscous Open Viscous Locked Locked Open Gyro-Clutch Viscous [2]

[edit] Atlas

The Atlas transfer case is an aftermarket, gear driven, fully synchronized unit. It is available in low range ratios of 2.0:1, 3.0:1, 3.8:1, 4.3:1, 5.0:1 & 6.0:1. The Atlas transfer case is manufactured and sold by Advance Adapters, to replace most stock Jeep transfer cases. See [3]

[edit] Overdrives and Underdrives

[edit] AMC

Borg Warner OD was available from early 1960 to 1969.

Laycock-DeNormanville OD was available from 1974 through 1976 for inline six with 150-T and V8 torque tube cars with the T-89.

The Borg-Warner overdrive case is 11-3/4 inches long (less torque tube adapter, if required). This includes the 1-1/2 inch thick adapter.

A complete T-96 with OD is 18-3/4 inches long from front of case to end of tailshaft housing. The OD unit is the same for all.

[edit] Jeep

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[edit] Transmission to Transfer Case Adapters and Clocking

Transmissions end with a splined tailshaft, more commonly called an output shaft. When one or more auxiliary units are bolted to the main transmission, these are called adapters or tailhousings. All factory applications with a 4wd transfer case require an adapter and many upgrade transmissions that would otherwise be incompatible can be adapted to Jeep transfer cases.

Clocking refers to the angle at which the transfer case is angled off of the horizontal plane. Stock Jeep angles for the Dana 300 (1980-1986) are usually 23° and stock Eagle and Jeep/New Process angles are usually 13°. There are many reasons why a person may want to change this angle, ground clearance and front driveshaft clearance being chief among them. Some aftermarket adapters feature flanges with multiple clocking options; an example being Novak adapters.

[edit] Bell housings

The bell housing bolt pattern for the old 196 is the same as the modern 1964 through 1971 199 and 232, but the 196 had different dowel pin sizes.

When AMC dropped the Gen-1 V8 engines in 1966, the bell housing changed. All later V8 bell housings are the same. The bell housing for six cylinder engines changed in 1972 when AMC went from Borg-Warner to Chrysler transmissions to match the V8. The flywheel also changed from 153 teeth (a common Chevy size) to 164 teeth (a common Ford size).

The Iron Duke I4 has some dispute over transmission bolt pattern between the Small Six and the BOP. The later AMC I4 had a Chevrolet Small Six bolt pattern, and this was retained for the life of the engine. AMC often used lighter duty transmissions with these engines.

Engine family Bell housing style Flywheel/Flexplate
GEN-1 V-8 Engines AMC Gen 1 V-8 xx
Early AMC I-6 AMC Gen 1 I-6 153 teeth
Wilys 230 I-6 xx xx
GEN-2 and 3 V-8s AMC Late Model 164 teeth
Modern AMC I-6 AMC Late Model 164 teeth
Buick 232 V6 BOP V-8 153 teeth
Iron Duke Chevrolet V-6/V-8 xx
AMC 150 I-4 Chevrolet V-6 xx

[edit] Applications

See List of AMC Transmission Applications

[edit] See also

Companies

Parts

[edit] External links