Torque Converter: Notes

WARNING: This page is about a different car, the 2015 Jaguar XF, 2014 Jaguar XF, and 2013 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.

The 8HP70 transmission is fitted with a twin torsional damper torque converter. The damper enables a more direct engine connection for highly efficient power transmission when starting and shifting. The inner spring set is connected directly to the transmission, the outer spring set responds to torque from the engine via the lock-up clutch. When the lock-up clutch is applied, the hydro-dynamic circuit is bypassed and torque is transferred directly to the transmission input shaft. In comparison to conventional torque converters, the twin torsional damper applies the lock-up clutch earlier, therefore improving driving comfort at low engine speeds and increasing fuel efficiency by enabling the engine to be operated at lower RPM levels.

When the converter lock-up clutch is not applied, torque is transferred hydro-dynamically. Power from the engine is transmitted via the pump and turbine to the transmission input shaft. When the converter lock-up clutch is applied, the hydro-dynamic circuit is bypassed, torque is transferred directly via the lock-up clutch and the twin spring sets. The turbine inertia is coupled between the two spring sets which improves disengagement, helps reduce wear on the transmission and improve noise insulation.

The torque converter is the coupling element between the engine and the transmission and is located in the torque converter housing, on the engine side of the transmission. The driven power from the engine crankshaft is transmitted hydraulically and mechanically through the torque converter to the transmission. The torque converter is connected to the engine by a flex plate attached to the rear of the crankshaft.

The torque converter comprises a twin torsional damper. an impeller, a stator and a turbine. The torque converter is a sealed unit with all components located between the converter housing cover and the impeller. The two components are welded together to form a sealed, fluid filled housing. With the impeller brazed to the converter housing cover, the impeller is therefore driven at engine crankshaft speed.

The converter housing drive plate has four threaded bosses, which provide for attachment of the engine flex plate. The threaded bosses also provide for location of special tools which are required to remove the torque converter from the torque converter housing.