And since the Turbo 400 does not rely on computer controls, it was adapted to a wide range of configurations. Roller clutches are very strong, but lack the total surface area of engagement found with sprag-type clutches. When excess charge pressure is generated into the torque converter it can then be physically thrust forward from that high fluid pressure. Roller clutches are used in many General Motors transmissions. Since the torque converter spins at engine crankshaft speed, the outer housing is always rotating when the engine is in operation. This provides a positive stop for the compressed clutch pack when the apply piston forces the steels and frictions tightly together.
Valve Body The valve body is basically the brain of the transmission. From left to right, top to bottom are: valve body, output shaft, pump stator, planetary gear sets, rear band, pump body and gears, direct drum, direct clutch pack, forward drum and input shaft, forward clutch hub, direct clutch hub, direct clutch pack, intermediate pressure plate, intermediate clutch pack. The other race is smooth, and rotates easily in one direction. Inside of these automatic transmissions, are torque converters, oil pumps, clutch packs, bands and servos, accumulators, planetary gears, sprag and roller clutches, as well as bushings, thrust washers, governors, and modulators. Flyweights and springs are used and calibrated to provide the appropriate signal to the valve body for controlling gear changes. It can be difficult to get a good grip on it; the outer snap ring and clutch and steel plates can be removed if needed left. Pressurized oil is routed behind the piston, causing it to move and apply force to the clutch pack.
Many aftermarket shift kits recommend, and even supply, components to eliminate accumulators and their function. A special thanks to Pete Nichols and all the staff at Hughes Performance, who made this informative trip through the construction of their Turbo 400 possible. The valve body routes fluid flow to the correct transmission components to provide constant vehicle motion through gear changes, while effectively transferring engine power to the rear wheels. As far as the automatic transmission is concerned, these efforts save great expense. The stator assembly is splined directly to the stationary input splines on the front of the transmission. A spring cage, held in place with a snap ring, is used to move the piston away from the clutch pack when the fluid pressure is removed from behind the piston. The diameter of the piston and the tension of the spring behind it are precisely tuned to allow the component to engage without creating an overly hard or firm shift.
Remove Valve Body and Governor Filter Step 1: Remove Oil Filter Remove the special bolt that holds the oil filter in place. The torque converter is used to provide the driving force for the transmission. Written by Cliff Ruggles and Posted with Permission of CarTechBooks. This can be a dangerous practice. Step 2: Remove Manual Shaft Remove manual shaft from the case Step 3: Remove Manual Shaft Seal Important! It is quite common to find thick and thin steel plates in the same drum, or the thin plates may be used to add frictions, thus creating more space.
In some cases they are completely worn out, which allows the planetary pinions to ride directly against the steel backing washers. While these transmissions are respected for their durability and versatility, there always comes a point where the old transmission shows signs of wear. Low-vacuum situations, which require heavy-throttle or full-throttle application such as when passing another vehicle , provide a lowvacuum signal to the transmission via the vacuum modulator. Some accumulators also have a portion of the applying transmission fluid routed in behind them to assist the spring in slowing the movement of the piston. This basic arrangement of parts is used for all automatic transmission clutch packs.
A great deal of common sense must be applied here; if the parts seem excessively loose, compare the planetary gearset to a new one. This allows the assembly to rotate freely in one direction. These are also in mesh with an outer gear or carrier. From there, the billet steel intermediate shaft, made of a proprietary material, is installed. Plus factory and aftermarket upgrades, parts interchange advice, and a transmission identification guide. The basic arrangement of the components varies, but the end result of these components working together is the same: They are designed to efficiently and effectively use engine power to propel the vehicle over a wide variety of operating conditions.
I'm not sure if mine was just a misprint or if there is a problem with this edition in general. This not only makes them very strong, but they also distribute their load over a greater surface area. We modify the center support to dual feed the direct frictions with fluid which exponentially increases the holding ability of the direct clutch pack. Time saving tips are part of every buildup. A spring cage is used to keep the apply piston away from the clutch pack. At low speeds, or at nearly idle engine speed, there is enough distance between the two fans to allow one to turn without moving the other. The clutch pack must overcome spring pressure.
The oil leaving the oil pump must overcome spring pressure to maintain flow to the rest of the unit. The valve body is tied in hydraulically to the governor on transmissions that are not computer controlled. Put it in a safe place until reassembly of the unit. Time saving tips are part of every buildup. As well, a torque converter feed balance circuit, an additional fluid passage, is added to create a balance in the converter fluid feed circuit. The Turbo 400 pan is longer than it is wide.
The Hughes team installs the output shaft into the back of the planetary output carrier, also retained by a snap ring. I laid each part out very carefully in a long line across the workbench, while paying very careful attention to which direction it had been in. Most units use either 3- or 4-pinion planetary gearsets with helical-cut gear teeth. Planetary gearsets are used in automatic transmissions to provide various gear ratios. The Turbo 400 was the automatic tranny of choice for its durability and simplicity, not to mention versatility since it could handle whatever you threw at it; family car, hot rod, race car, dragster, off-road truck or any vehicle needing a durable and reliable automatic transmission.
Next are the forward, direct, and intermediate clutch packs — a combination of red racing forward and direct clutch packs and High Energy frictions intermediate clutch packs. The internals of the torque converter allow the vehicle to stop and the engine to continue to operate without having to disengage a clutch. When overhauling this transmission, there are a couple of areas that need special attention. United States Army Drill Sergeant J. The High Energy frictions are likewise exceptionally durable and provide a cushion as they apply, resulting in less shock to the intermediate sprag.