The valve body is the control center or brain of the automatic transmission. It contains a maze of channels and passages that direct hydraulic fluid to the various valves which then activate the appropriate clutch pack or band servo to smoothly shift to the appropriate gear for each driving situation. Each of the many valves in the valve body has a specific purpose and is named for that function. For example the 2-3 shift valve activates the 2nd gear to 3rd gear up-shift or the 3-2 shift timing valve which determines when a down shift should occur.
The most important valve is questionable, since every valve is vitally important. The one that gives you direct control over the transmission is the manual valve. The manual valve is directly connected to the gear shift handle and covers and uncovers various passages depending on what position the gear shift is placed in. When you place the gear shift in Drive, for instance, the manual valve directs fluid to the clutch pack(s) that activates 1st gear. it also sets up to monitor vehicle speed and throttle position so that it can determine the optimal time and the force for the 1 – 2 shift.
The other valve, should your valve body have it is the T.V. valve, and the governor. These components apply to non computerized transmissions such as the T-700R4 Chevrolet transmission and many other transmissions.
On computer controlled transmissions, you will also have electrical solenoids that are mounted in the valve body to direct fluid to the appropriate clutch packs or bands under computer control to more precisely control shift points. and, a manual lever position switch too.
Simply put, the valve body makes all of the shifting decisions for your transmission. Different inputs from various switches and sensors provide the valve body with the necessary information for the transmission to do it’s job properly. Got a question about a valve body, or a comment? Ask it right here in the comment area of GotTransmissions.com Blog..