As promised in Part II, we will tackle the cooling and electronics aspects of the GM Performance Parts (GMPP) 4L85-E SuperMatic trans swap in this article. First, here's a brief review.
Part I (Feb. '10) of this series covered the history and development of GM's four-speed overdrive transmissions and introduced GMPP's latest unit, the 4L85-E SuperMatic, which shares its forward gear ratios of 2.48:1, 1.48:1, and 1:1 with the vintage Turbo 400, but adds an Overdrive gear of 0.75:1, electronic control, and a much higher torque capacity over the 4L80-E and 4L85-E that came before it. With a torque capacity of 685 lb-ft, the SuperMatic will live behind many a high-torque Pontiac buildup
In Part II we highlighted the mechanical aspects of swapping the transmission and the included lockup converter (approximately 1,800-2,000-rpm stall speed) into a '74 SD T/A in place of the factory Turbo 400. We also addressed frequently asked questions regarding a swap such as this
In this installment, we discuss the installation of the cooling lines and cooler, the required GMPP transmission control unit (TCU), and ancillary components to make the trans function properly. Next issue, we will discuss tuning the trans via a laptop using GMPP's software
The installation and tuning of the transmission took place at Classic Restorations in Pine Island, New York. The business' owner and HPP contributor, Melvin Benzaquen, also owns the SD T/A. Classic Restorations Technician Scott Hand performed the swap.
Features You Can Control
How much control does the transmission control unit provide the owner?
Wide Open Throttle (WOT) Minimum Shift Time: Set the time delay from the shift signal to the actual shift by the trans.
Part Throttle Shift Time: Set the time delay from the shift signal to the actual shift by the trans.
Minimum TPS % for WOT: Determine the throttle position the TCU recognizes as WOT to make the shift timing rpm controlled.
Maximum TPS % for Idle: Determine the TPS threshold between idle and part throttle.
Downshift Hysteresis MPH: Set the difference in the upshift (acceleration) to downshift (deceleration) mph at part throttle.
Reverse LP Kick %: Determine the percent of additional line pressure added when shifting into Reverse.
Econ/Perf LP Kick %: Determine the percent of additional line pressure added when the TCU is in Performance mode.
WOT Parameters: Dial in upshift rpm for each gear. Set the mph for forced downshift for each gear.
TCC Lockup Parameters: Change several variables of torque converter lockup functions.
Minimum MPH for TCC Lockup: Dial in the mph limit under which you do not want the converter to lockup.
TCC Lockup Rate: Dial in the feel of the converter lockup by adjusting the time it takes to complete the function. The more time (bigger number) the softer the
apply will be.
Converter Lockup Delay: Eliminates converter hunting by allowing a settable time value between apply and release.
Engine Braking Parameters: Set the maximum mph at which the trans will make a forced manual downshift.
Slapstick Parameters: Can work with an electronic, manually controllable shifter.
Force Motor Tables: Adjust shift feel for each gear via line pressure curve settings.
The TCU also has dashboard overviews to help monitor vehicle sensors and has data logging capability.
If the idea of dialing in all of these parameters intimidates you, then don't do it. The transmission is delivered to you with default settings that allow you to drive the car normally without reprogramming anything. However, if you want to dial in each aspect of the transmission's operations to your liking, you can.
B&M's Hi-Tek Cooling System...
B&M's Hi-Tek Cooling System is a plate-fin oil-to-air cooler with its own draw-through fan. A bi-metal temperature switch turns the fan on at 176-degrees (+ or - 5.4 degrees) and turns it off at 140-degrees (+ or - 5.4 degrees). Since the cooler has its own fan, it can be mounted in different locations. However, the fan has to be at least 6 inches from an exhaust source and 2 inches from the closed hood, the wheelwell or the firewall, or 1 inch from the radiator fan. Rubber isolation mounts are recommended, and the unit should not be mounted to an area that will see lots of flex when the car is driving or it may crack the cooler and cause leaks.
Here are the electrical connections...
Here are the electrical connections for the fan. It's very important to verify correct polarity when wiring the fan or it will turn in the opposite direction and diminish cooling efficiency greatly. A 15-amp inline fuse was employed per the diagram.
This is a test fitting. Scott...
This is a test fitting. Scott was able to fit the unit ahead of the A/C condenser, as there was no room behind the radiator. He will remove the unit and reorient it so the thermal switch is at the bottom, instead of the top, to eliminate possible cavitation of the fluid, which would result in false temp readings. He will also install rubber spacers at the attachment points to provide a 1/4- to 1/2-inch air gap from the mounting surface, and also to further isolate the unit from vibrations. Even though this mounting point seems counterintuitive, since the fan is a draw-through design, B&M says it should still work well. Other possible mounting points, according to B&M, are under the car, above the fenderwell, and on the firewall.
The hoses were routed along...
The hoses were routed along the pan rail toward the back of the engine. Small brackets were fabricated to keep the hoses in place. (Each one will be fitted with rubber grommets to protect the hoses).
To transport hot trans fluid...
To transport hot trans fluid to the cooler and deliver cool fluid back, pre-bent hard lines pirated from a Chevy truck cooler with 1/2-inch NPT fittings at the forward end to attach to the braided hoses and quick-disconnect fittings at the trans end to mate with Dorman quick-disconnect trans line connectors were installed.
All fitting threads had anti-seize...
All fitting threads had anti-seize compound applied. The Dorman fittings were torqued to 28 ft-lb.