Volume III, Issue 10, Page 31


Electronic transmission controllers for overdrive automatics

As the market has become privy to many more variations of electronically controlled automatics, it was only natural for hot rodders to step in and enhance the processes for increased efficiency, better performance and “feel,” all without sacrificing an ounce of reliability. Here are six such companies that provide similar services, all of them engineered with experience in high-tech industries (read aerospace as well as OE), the best equipment, the latest technology, and by the propulsion of years of hot-rod savvy.



You know the frustration. That last bit of control and calibration eludes you like a greased pig. If you only had a pluck-your-magic-twanger box to give your stuff a sliver more information or confirmation that’ll make it run smoother and more effectively than the next guy’s.

Apply the GMCOPO Automatic Transmission Control Box (ATCB) to a 4L60E transmission and then lock it in Second gear to prevent up- or downshifting during the test. Locking the transmission in a single gear allows for a more consistent measurement of engine torque and at a lower engine speed.

The ATCB is a multi-tasking device able to apply the torque converter clutch which facilitates calibration of ignition timing and A/F ratios over a broader range of engine speeds and throttle openings. It means that you can also determine torque output below the stall speed of the converter and quickly evaluate a variety of shift and converter lock-up points. Simply, the ATCB affords the ability to choose the gear as well as the moment the torque converter is applied for any GM electronic four-speed automatic, including front-wheel drive cars.

As a kit, the ATCB includes the control box (with torque converter control) and gear selector, a 6-foot power cord that plugs into the cigarette lighter, two 12-foot control harnesses: one for the 4T40E transaxle and 4L80/85E and the other for the 4T65E transaxle and 4L60/65/70E transmissions. A foam-padded carrying case holds it all. Adjunct to the electronically controlled transmissions, the ATCB can also be adapted to lock up the converter clutch of the TH125C, 200C, 2004R, 3T40, 350C, and 700R4/4L60 transmissions.

GMCOPO Factory Engineered Performance
248 275-5828
Auburn Hills, MI 48321

The first test was made “free range.” Without the ATCB to monitor rpm and hold the transmission in Second gear, you can see how very erratic the torque curve and engine speed plots become. Click on the graphs for large versions. Essentially, the ATCB is a tuning tool that keeps the transmission from messing up the tuning process by hunting for gears on the upshift and downshift cycles. Look at the graph: the keyword here is smooth. It also allows the operator to make quick evaluations (e.g., reprogramming shift points, etc.) either on the street or at the dragstrip, thus eliminating the need to re-flash the CPU.