TCI Torque Command 904 Transmission - Inside The Aftermarket 904

A major weak link in the 727/904 is the overrunning clutch, also referred to as the sprag. When the transmission is in Low gear, the rear clutch pack is engaged causing the front planetary gears to turn clockwise. This turns the sun gear counterclockwise along with the rear planetary cage, which is splined to the rear drum that is held stationary by the one-way overrunning clutch. When you come out of a burnout in First gear and the tires hook, the shock rips the overrunning clutch out of the transmission case and it's destroyed. Our trans has a new overrunning clutch, and TCI rightly assumes we are going to do burnouts in Second or High gear to keep this from happening. There are bolt-in sprags that can also help, but it is better to either shift out of First in the water or start in Second or your case will look like this one.

The TCI trans comes with a mild shift kit that is capable of healthy 1-2 barks and the ability to shift into manual Low. It also allows you to cruise around in Drive and let the trans do the work. The TorqueFlite uses a throttle-valve circuit to regulate main-line oil pressure in relation to the engine load and speed. For this you need to connect the kick-down lever to the carb, or the transmission will shift soft with low pressure at high rpm and burn your clutches, likely on the first pass. Wedging the throttle valve to the WOT position won't allow the transmission to shift without a full-throttle pass. And you really can't do that on the street that often, can you?

Galante also adds a heavy-duty kick-down apply linkage. In some cases, the stock linkage will flex, reducing the pressure on the clutch drum and reducing your fun. But that's only the tip of the iceberg. If you want to spend a few thousand dollars for a transmission to go behind your 1,000 hp, you can buy virtually every component of the 727/904 in aluminum for weight savings with a few steel tidbits for strength.

Aftermarket transmissions have improved geroter front oil pumps for cooling and longevity. On the left is the 727, on the right is the 904.