This is a great article. If you are building a hot rod from scratch or you are taking your muscle car
to a modern level you will find some good information in this piece. I toyed with the idea of putting a modern manual 5 speed trans in my 70 Mustang, but I opted for a rebuild Shelby 4 speed manual. (Check out all 3 parts.)
Derided as “slushboxes” in the days when hot rodding was young, automatic transmissions have long since closed the performance gap and won the respect of (at least some of) the most dedicated lead foots. Today, even the fuel-economy advantages of the old-standard stick shift are more memory than reality, as the shiftless set has drawn even with, or pulled slightly ahead of, the shifters. Backing up these advances is a great deal of detailed engineering, especially of the electronic variety.
But a lot of it’s simply due to more gears—a wider range of ratios, allowing for relaxed, low-rpm cruising with peak torque still available on demand. About 10 years ago, a four-speed automatic with a lockup converter was the hot ticket to optimize performance with economy. Now the OEMs are building five-, six- and seven-speed automatics—and hot rodders want them, too.
Not that the shift-for-yourself crowd has been caught napping—six gears are now the required minimum in any respectable OEM performance car, and that’s left three-pedal rodders craving more ratios, too.
More Is Better
“Enthusiasts in every segment of the hot rod and muscle car markets are removing traditional three-speed gearboxes and replacing them with modern four-, five- and six-speed transmissions,” said Stanley Poff, who heads product and sales for TCI Automotive in Ashland, Mississippi. “As they experience modern overdrive automatics in their daily drivers, they become more inclined to want the same driving experience in their hot rods.”
TCI’s new 6x Six-Speed can be adapted to most GM small-block, big-block or LS engines; Ford small and big blocks; and Chrysler small blocks, big blocks and late-model Hemis.
“We build it in a modified GM 4L80E case that’s been machined to accept modular bellhousings, and we keep all of the Reid Racing bellhousings in stock,” Poff said. “We can put together a complete package for all of those applications, including the transmission, bellhousing, EZ-TCU electronic control, cooler, shifter (conventional and/or paddle-type), TCI transmission fluid and a dipstick.”
TCI currently offers the 6x in two models, rated for 850 and 1,000 horsepower, respectively. Models for 1,250 and 1,500 horsepower are in the works, according to Poff.
The market has also responded well to the company’s EZ-TCU, he said.
“It allows you to retrofit a modern electronically controlled automatic transmission, such as our 6x, or the GM 4L60E, 4L65E, 4L70E, 4L80E or 4L85E, to a carbureted engine, or an engine with a self-tuning EFI system such as the FAST EZ-EFI,” Poff said.
TCI worked with FAST to develop the EZ-TCU.
“It follows the FAST model of being extremely user-friendly and easy to install even by people who lack either tuning or electronics experience,” Poff said. “We sell a lot of EZ-TCU units to people who want to put a crate engine and electronic transmission in a classic street rod or muscle car.”
Pete Nichols, sales manager for Hughes Performance in Phoenix, pointed to the classic muscle car market, where “more and more people are building these cars with significantly higher-than-stock levels of horsepower and torque,” he said. “That requires a premium, high-strength aftermarket torque converter and transmission assembly.”
To meet these demands, Hughes now builds all of its GM 700R-4, 200-4R and Ford AOD transmissions with the upgraded, constant-pressure valve bodies.
“These valve bodies contribute to improved shift quality and more consistent shift timing, while reducing the possibility of premature transmission failure due to a broken or incorrectly adjusted throttle-valve (TV) cable,” Nichols explained. “The new design also eliminates a lot of the complexity and hassle associated with the TV system on these transmissions, so retrofitting them into older cars is easier than before.”
Hughes has also introduced a custom bellhousing system that allows builders to bolt the popular GM 4L80E behind a wide variety of GM, Ford and Chrysler engines without using an adapter. The company offers custom 4L80E options for applications producing 500–1,500-plus flywheel horsepower, and for virtually any popular V-8 engine.
Nichols emphasized the need to properly flush the transmission cooler and cooler lines before installing a new torque converter.
“Debris gets easily trapped in the old cooler and then it gets flushed out during the initial run-in period, inevitably working its way into the valve body, governor, etc.,” he said, adding that getting a new cooler is the best way to prevent debris-related failures.
Part 2 coming up.