Bob's Resource Website (2007)

(Transmission Info)

Automatic transmission housings are typically aluminum castings. Aluminum housings are lightweight and are designed to allow for quick heat dissipation. The torque converter and transmission housings are normally cast as a single unit; however, in some designs the torque converter housing is a separate casting.

By bolting the torque converter housing to the transmission housing, engineers can use the same transmission with different sized torque converters to meet the specific needs of particular types of vehicles. Also, at the rear of some transmission housings is a bolted-on extension housing.

This allows for the use of housings of different lengths; therefore, the transmission can be used on vehicles with different wheelbases.

Transaxle housings are typically comprised of two or three separate castings bolted together. One of these castings is the torque converter housing. Since FWD vehicles do not use a drive shaft to convey power to a drive axle, transaxles are not fitted with an extension housing. Although they serve many of the same purposes as a transmission, transaxle housings are considerably different in appearance from a transmission housing.

Transmission housings are cast to secure and accommodate key components of the transmission. For example, linear keyways are cut into the inside diameter of the housing. These keyways are designed to hold a multiple-disc clutch assembly in position in the housing. Some transmission housings have round structures projecting from the side. These are the cylinders of the servo assemblies in which pistons, springs, and seals are fitted to operate the bands of the transmission. On some transaxles, these projections house the governor assembly and are sealed with a removable cover.

The transmission's fluid dipstick and filler tube are used to check the level of ATF and add ATF to the transmission. This tube is normally located at the front of a transaxle housing and the right front of a transmission housing.

Some housings have band adjusting screws located on the opposite side of the housing from the servo assemblies. These screws are adjusted to compensate for band wear. The band adjusting screws can have square or hex heads and are locked in place with a jam nut.

These pages and programming contained therin are © 1996 - , Bob Johnstone and may not be reproduced without the permission of rfjohnstone at cox.net (Bob Johnstone) All Rights Reserved.
Some technical opinions are my own from experience, other informational data is from online sources with credits when available and while care has been taken to be as accurate as possible, it is offered only as a guide and caution should be exercised in the application of it.