One of the key things you have to decide when you order the E-Rod package from GMPP is what transmission you’d like have: manual or automatic. Will it be direct connection or torque multiplication? Gearbox or slushbox? Three pedals or two?
Here’s the star of the show: the GMPP 4L70E ($3,049, street price). The gear ratios are still the standard pack found in the 700-R4 and 4L-series at 3.06, 1.62, 1.00, and 0.70. The 4L70E also gets several key upgrades targeted at hot rodders: • Rated up to 480 hp • Includes friction-reducing components that send more power to the axle • Thirteen-vane pump with a heat-treated stator support • Five-pinion input and reaction carriers • Heat-treated sun shell • Heavy-duty low roller clutch assembly • Upgraded 3-4 clutch pack and a high-energy 2-4 band • Needle bearing assemblies replace conventional thrust washers to reduce power loss and heat buildup
It’s a true moment of decision, since the calibration in GMPP’s E-Rod ECU is slightly different depending on the trans chosen, and must be matched correctly as part of the emissions compliance of the package. It’s a tailored solution. For the EcoNova project, the answer was an obvious one: automatic. Comfortable cruising is the priority, but also we didn’t feel like enduring the hassle of tracking down, restoring, and swapping in the necessary pedal assembly. Plus, with GM Performance Parts’ latest line of SuperMatic transmissions, you’re really not giving up much more than a left-leg workout.
The SuperMatic designation is the retrofit kit name for GM’s 4L-series of transmissions, which all trace their roots back to the original 700-R4 introduced in 1982, and redubbed the 4L60 in 1990. The electronic shift-controlled version of the 4L60 (the 4L60E) arrived in cars in 1994, and it’s been evolving ever since with the 4L65E, and the latest and greatest, the 4L70E. The big 4L80E (derived loosely from the venerable Turbo 400) also has its own SuperMatic kit for those making big torque or horsepower.
For our purposes, the highly refined and strengthened 4L70E SuperMatic made the most sense. Not only is it significantly lighter than the 4L80E and rated to handle much more power than we’ll be making, it’s also roughly the same dimensions as the 700-R4, which we already know fits perfectly in the EcoNova’s trans tunnel. That means getting it in is also similar to the familiar 700-R4 swap, since the 4L70E is based on the same architecture. Nevertheless, there’s a bit more to getting it into a vintage machine, since this trans is fully electronic.
In this case that’s actually much more of a benefit than a hassle since there’s no throttle valve (TV) cable to deal with, which is great considering the E-Rod’s required electronic throttle body has no provisions for attachment. Rather than a complication, we’d call it an elegant simplification. But the benefits go much beyond that; those electronic actuators and solenoids that manage the valvebody and actuation system for the clutches and bands offer far more control over the transmission’s final performance. We’ll delve into that more down the road, for now let’s just get it installed!
