Even though some later units also provided reference signals to the ECM, shifts were still controlled by reference from the governor and TV cable. Earlier 4L60 units also used a wiring harness routed through pressure switches to control TCC operation. The 4L60E transmissions will not use a governor or a TV cable. Shift changes and torque converter clutch (TCC) operation is completely controlled electronically. Note that this unit uses several switches in the valve body. Here is a view of a typical wiring harness for a 4L60E transmission with the oil pan removed. The TCC solenoid was incorporated into the transmission’s oil pump. The TCC was controlled to lock and unlock in a variety of situations, to avoid overloading the engine and to maximize vehicle performance in any gear and vehicle speed. This concept had already been used for several years in TH350 transmissions with good success. Adding a clutch to the torque converter transfers all engine power directly to the transmission and onto the differential. The 700- R4 transmissions also incorporated a lock-up torque converter to cease all torque multiplication once the TCC (torque converter clutch) was applied. Some consider the drop from 3.06 to 1.61 a bit steep, but in actual use it is barely noticeable. The second-gear ratio was improved to 1.61:1, and third gear remained at 1:1. Moving up to the 3.06 first-gear ratio increased off-idle performance of the vehicles it was installed in considerably. The 700-R4 transmissions received a drastically improved first-gear ratio compared to existing transmissions, most specifically the TH200, TH350, and TH400 (2.74, 2.52, and 2.48, respectively). You can copy and paste this link to share: SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in.

For a comprehensive guide on this entire subject you can visit this link: This Tech Tip is From the Full Book, GM AUTOMATIC OVERDRIVE TRANSMISSION BUILDER’S AND SWAPPER’S GUIDE. The actual end result was dismal overall vehicle performance. The aim was to minimize pollutants that exited the tailpipes. Before attempting to integrate an overdrive transmission into their vehicles, the past decade or so had been spent by manufacturers reducing engine displacements and lowering numerical axle ratios to slow the engines down considerably. At the time, emissions standards were tightening and General Motors was hard-pressed to increase fuel economy across the board for their production vehicles. The 700-R4 transmission first came into production in the early 1980s.

History of the 700r4 transmission