Jeep TH400 Technical Information
Peanut Butter
Full Time Jeeper
- Posts
- 2,591
- Thanks
- 13
- Location
- Boerne, Texas
- Vehicle(s)
- 1979 Jeep CJ7 TH400 Automatic 258 I6 Quadratrac Amc 20 rear & Dana 30 front, 32 x 11.5 x 15 tires. Currently a Complete Custom Rebuild in progress.
Also I own a 2001 Jeep Cherokee, White, all stock with 4.0L. automatic, and police package. Best part of that is it came with leather seats! This package also has the NP242 Transfer Case, 8.25 rear end, and trailer towing package.
This Jeep TH400 Technical Information thread is based on information that I have gathered after discovering that my own TH400 
was not a Chevy housing but a BOP Housing from a Cadillac.
The Turbo Hydromatic 400 automatic transmission was found in Jeep CJs from 1976 to 1979. It was only in the CJ7 due to it's length. :down: It was also found in the full size Jeep SJs from 1967 to 1979. There are two different housings made for the TH400 found in Jeeps. One is referred to as the AMC Jeep Housing and the other is the GM Housing. Within the GM Housing there are three different bolt patterns that correspond to different GM makes. Here they are:
The first is the Chevy Bolt Pattern
The second is the Buick, Olds, Pontiac, and Cadillac bolt pattern commonly referred to as the BOP.
The third pattern is a combination of the other two, known as the Dual Bolt Pattern.
Here is a picture of the Jeep Housing. It can be easily identified by the numerous bolt holes.
There are two other ways to identify which TH400 you have. If it is still there and still readable, you should find a small plate riveted to the passenger side of the transmission. :booze: This tag will have a design in different colors that was printed on it. There will also be a set of stamped numbers incase the printing is worn off. The stamped numbers on the plate are coded. Fist is the year it was built. In my example 1976. The next two digits are two letter codes for the make and model of the vehicle it was made for. In my example J stands for Jeep, but I'm not sure of what model the M stands for. Here is my example:
Here are some of the other codes. A complete list can be found in many TH400 repair books.
B - Buick; A - Cadillac; P - Pontiac; O - Olds; C - Chevy; MA - AM General Military Truck; N - Checker; Z - Jaguar; K & J - Jeep; and R - Rolls Royce
The second way to identify the type of TH400 is the serial number which is usually located on the drivers side bottom flange. The first three digits indicate the plant it was made in, the year, and the month. I don't have this chart but you might find it on the internet by doing a search. The picture below shows the stamped serial number:
The TH400 is a three speed transmission. It has the following gear ratios:
1ST - 2:48 2ND - 1:48 and 3RD - 1
All Jeeps came with a steering column shifter that incorporated a solid linkage. There are however many different after market shifters such as the solid linkage Lokar (Lokar: Automatic Transmission Shifters) to the cable B&M (B&M HOME B&M) or the custom cable JB Custom Fabrication Shifter (JB Custom Fabrication). You can even create a hybrid system by using the OEM Column Shifter and a Lokar cable (Lokar: Column Cable Shift Linkage).
No mater what type of TH400 you might have, you can be sure you are in good hands with a heavy duty transmission. Many of the TH400 were found in Chevy trucks, both 2wd and 4wd. The TH400 can handle lots of power and torque. It was used on big block 454 & 396 Chevys, but was also found on the AMC I6. This transmission with for the most part all mechanical shifting is still used on many different type of vehicles. The newer 4L80 and 4L60 are based off of this TH400. With a book and a video, a person with some good mechanical skills can rebuild this transmission at home, making it one of the most desired transmissions in 4wd wheeling. Hope this information is helpful to you all. :driving: Thanks, Rod
was not a Chevy housing but a BOP Housing from a Cadillac. The Turbo Hydromatic 400 automatic transmission was found in Jeep CJs from 1976 to 1979. It was only in the CJ7 due to it's length. :down: It was also found in the full size Jeep SJs from 1967 to 1979. There are two different housings made for the TH400 found in Jeeps. One is referred to as the AMC Jeep Housing and the other is the GM Housing. Within the GM Housing there are three different bolt patterns that correspond to different GM makes. Here they are:
The first is the Chevy Bolt Pattern
The second is the Buick, Olds, Pontiac, and Cadillac bolt pattern commonly referred to as the BOP.
The third pattern is a combination of the other two, known as the Dual Bolt Pattern.
Here is a picture of the Jeep Housing. It can be easily identified by the numerous bolt holes.
There are two other ways to identify which TH400 you have. If it is still there and still readable, you should find a small plate riveted to the passenger side of the transmission. :booze: This tag will have a design in different colors that was printed on it. There will also be a set of stamped numbers incase the printing is worn off. The stamped numbers on the plate are coded. Fist is the year it was built. In my example 1976. The next two digits are two letter codes for the make and model of the vehicle it was made for. In my example J stands for Jeep, but I'm not sure of what model the M stands for. Here is my example:
Here are some of the other codes. A complete list can be found in many TH400 repair books.
B - Buick; A - Cadillac; P - Pontiac; O - Olds; C - Chevy; MA - AM General Military Truck; N - Checker; Z - Jaguar; K & J - Jeep; and R - Rolls Royce
The second way to identify the type of TH400 is the serial number which is usually located on the drivers side bottom flange. The first three digits indicate the plant it was made in, the year, and the month. I don't have this chart but you might find it on the internet by doing a search. The picture below shows the stamped serial number:
The TH400 is a three speed transmission. It has the following gear ratios:
1ST - 2:48 2ND - 1:48 and 3RD - 1
All Jeeps came with a steering column shifter that incorporated a solid linkage. There are however many different after market shifters such as the solid linkage Lokar (Lokar: Automatic Transmission Shifters) to the cable B&M (B&M HOME B&M) or the custom cable JB Custom Fabrication Shifter (JB Custom Fabrication). You can even create a hybrid system by using the OEM Column Shifter and a Lokar cable (Lokar: Column Cable Shift Linkage).
No mater what type of TH400 you might have, you can be sure you are in good hands with a heavy duty transmission. Many of the TH400 were found in Chevy trucks, both 2wd and 4wd. The TH400 can handle lots of power and torque.
It was used on big block 454 & 396 Chevys, but was also found on the AMC I6. This transmission with for the most part all mechanical shifting is still used on many different type of vehicles. The newer 4L80 and 4L60 are based off of this TH400. With a book and a video, a person with some good mechanical skills can rebuild this transmission at home, making it one of the most desired transmissions in 4wd wheeling. Hope this information is helpful to you all. :driving: Thanks, Rod
Rod
