Stall converter on trans am

Fluid couplings were introduced by Chrysler in , GM in and Ford in They provided relatively good efficiency when coupled, but they generally did not provide the desired standing start acceleration. The GM 4-speed Hydra-Matic solved this problem by incorporating a very low first gear 3. The first modern GM automatic was released in as the Turbo Hydromatic, and it incorporated a three-element torque converter, three forward gears and overrunning clutches that allowed the next higher gear to pick up the load from the preceding gear.

This eliminated shift timing problems that plagued some of the competing transmissions which had to come out of a lower gear before applying power through the next higher gear.

The entire line of current GM transmissions has descended from the TH What is the difference between a fluid coupling and a torque converter, and how do they actually transfer power? We have seen depictions of power flow through a fluid coupling as tow ordinary household cooling fans facing each other. One fan is powered up, and the air it blows causes the non-powered fan to turn. The fluid coupling does operate similarly to the fan example, except that automatic transmission fluid ATF is the medium used to transfer power.

The ATF for the fluid coupling and torque converters is furnished by the automatic transmission gear type oil pump.

Both halves of a fluid coupling are constructed identically with flat-type vanes. Refer to illustration No. It's from Page 9, '56 Hydro Shop Manual. The torque converter incorporates one major change from the fluid coupling: a third element the stator is designed into the unit. The stator consists of a finned element that fits between the driving member impeller and the driven member turbine , and it is mounted via a one way clutch to the turbine.

In addition, the vanes of the impeller and turbine are curved, and are oriented differently in the two units. The curved vane construction allows the ATF to change directions rather gradually as it passes between the impeller and the turbine.

This gradual change of direction imparts more force to the turbine as the oil strikes it. See illustration No. Upon engine startup, the transmission oil pump pressurizes the converter with ATF.

The impeller "throws" the ATF into bucket-like receptacles of the turbine and generates some pressure on the turbine in the same direction as the impeller is turning.

After striking the turbine, the ATF us deflected back toward the impeller. As the engine speed increases, additional ATF velocity develops due to impeller action, and without a stator installed, the ATF would be reflected back from the turbine to the impeller in a direction that impedes the impeller operation. With a stator installed, the stator vanes redirect the returning ATF so that it strikes the impeller elements in the correct direction.

This energy, added to the original energy transferred from the impeller to the turbine, is what causes the "torque multiplication" in a converter at low rpms. In a typical stock converter it is about a multiplication factor. As the rpm increases, the angle of the returning oil from the turbine changes and, at some point, the stator fins begin to impede the flow of ATF.

The one-way roller clutch in the stator allows the stator to begin to turn on the shaft so as not to affect the ATF flow. At that point, the converter is said to be "coupled," and the converter now operates at an approximate ratio. The stock TH torque converter multiples torque at low rpm so that a moderate-ratio first gear 2.

The torque converter multiplication and the 2. Second gear is ratio and Third is direct drive , so the steps between each gear are relatively small, which provides efficient and smooth shifts. Some torque multiplication also occurs in second and third gears at lower rpm. This rpm point is called the stall rpm, and it's determined by two factors: the power torque that the engine can deliver at that rpm and the converter slippage.

If a inch engine can stall a given converter to rpm, a engine would stall the same converter several hundred rpm higher due to the increase torque of the at What about the load the converter sees? If the typical vehicle described above with either a or is driven normally, it will move out briskly from a stop with minimum converter slippage.

However, if a lb. This exercise illustrates that converters are sensitive to both power and the load imposed upon them. The stall rpm does not change with load because the drive train is locked when the stall rpm is determined. However, the converter coupling is sensitive to load.

Thus, there can be no accurate description of the stall rpm and relative slippage of a converter unless both the low rpm engine torque and the load vehicle weight are known. Converter Stall RPM: The engine rpm that a given engine will reach at full throttle with the drive train locked.

Converter Flash RPM: The engine rpm that a given engine will reach at full throttle at the point the vehicle begins to move with no brake application. Converter Coupling Efficiency: The relative amount of slippage after the converter is "coupled. The physical size of stock converters will generally affect the coupling efficiency; the larger-diameter converts usually slip less than the smaller units.

However, modifications to the converter's internal design can change both the stall speed and the coupling efficiency, regardless of size. Also, the angles and shapes of the fins in the impeller, turbine and stator will have a major effect on both the coupling action and the stall speed of the converter. In the earlier days of converters and hot rodding, the hot tip was to install a smaller converter in place of the stock unit. This allowed the engine to reach a higher rpm before the converter began to transfer enough power to move the vehicle.

While this did provide some advantages of low-speed acceleration, it also caused excessive slippage at higher speeds. The slippage destroyed top speed and gas mileage, and also generated a large amount of heat in the ATF. Worldwide Shipping International options available. Secure Payments Your order is safe with us. Rating Required Select Rating 1 star worst 2 stars 3 stars average 4 stars 5 stars best.

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Add to Cart. Functional Lock-up Quick view Add to Cart. Features dual bolt pattern to fit any non LS flexplate. This torque converter is available in stall speeds ranging from to as much as rpm and features an anti balloon hub, furnace brazed cover tig reinforced fins, Torrington bearings and a lock-up clutch that has an even greater apply area than the full sized MM unit it replaces. This converter weighs over 10 lbs less than the stock converter which means less weight on the crank and a quicker revving engine.

Like all Phoenix Transmission converters, this unit is built to order for the perfect stall speed match for your application, and is computer balanced.

This is a great choice for a cammed up LS engine in a lightweight car that needs a higher stall speed for no creep at idle but still needs good street manners.

The clutch is oversized and has more surface area than the stock MM converter. This is our strongest Torque converter for the 4L80E transmission and is available in stall speeds up to rpm and applications up to HP. This converter features a billet 1 piece front cover with pilots for GM V-8 engines as well as LS1 style engines. We use a special clutch design that not only has a greater clutch surface area than any other single piston 4L80E converter but will also work with GM ec3 programming.

Other features include, full furnace brazing of all internal fins on both the cover and stator, heavy duty sprag and race, full Torrington bearings throughout, hardened hub, hardened turbine spline, anti ballooning plate, fully computer balanced. If you need a high stall converter for the 4L80E then this one can take the punishment! Features furnace brazed cover, fully tig reinforced turbine, dual Torrington stator bearings, hardened sprag race and heavy duty sprag, Anti balloon plate and hardened drive hub.

Like all of our Torque Max converters this is built per order and is fully balanced to 0 grams. Available in stall speeds ranging from rpm to rpm. These can be built with or without an internal clutch. Features furnace brazed cover, fully tig reinforced turbine, dual Torrington stator bearings, hardened sprag race and heavy duty sprag, anti-balloon plate and hardened drive hub. Also available for MM LS-1 applications. Comments from Tom! It was the fastest class the track allowed at this event.