To any hot rodder, a hard-running small-block with deep rearend gears blasting through the quarter-mile at over 7,000 rpm sounds great. But driving that same hot cruiser down the freeway at anything over 3,000 rpm gets old fast. To be able to blast low e.t.'s and effortlessly cruise the freeway, many hot rodders have discovered the benefits of overdrive automatics. But because electronic-overdrive transmissions are designed for computer-age vehicles, the dilemma becomes how to activate a lockup converter in a noncomputer musclecar.
The good news is that with a few hours of work and some know-how, that late-model automatic with its lockup converter can put your vehicle's performance into overdrive.
Recently, we spent the morning with Gene Christensen from Auto-Rite Trans-missions to learn just what is involved in wiring a TH700-R4's lockup converter into a noncomputer car. What we're doing here is using a Hobbs pressure switch to complete an electrical circuit that activates a solenoid in the transmission to apply the torque converter lockup when the transmission shifts into overdrive. To be able to demonstrate the steps easily, we used a transmission on a bench, but the procedure can be done with the transmission in the vehicle. Here's what we found.