SPECIFICATIONS
| CAUTION | Use only Shell M1375.4 Automatic transmission fluid. Use of any other fluids may result in a transmission malfunction or failure. |
| Description | Intervals |
|---|---|
| Normal maintenance | Filled for life. |
| Severe duty maintenance | Change the fluid at 48, 000 km (30, 000 miles) intervals. |
Note. Lubricants, Fluids, Sealers and Adhesives
| Description | Specification |
|---|---|
| Transmission fluid | Shell M1375.4 |
| Sealant | WSS-M4G323-A6 |
| Metal surface cleaner | WSW-M5B392-A |
| High temperature grease | Molecote FB180 |
Note. General Specifications
| Vehicle | Engine | Approximate Liters | Refill capacity approximate dry capacity, includes cooler and tubes. Check the level at normal operating temperature. DO NOT OVERFILL. If it is necessary to add or change fluid, use only fluid which has been certified by the supplier as meeting the Jaguar Cars Ltd specification shown. U.S. Quarts |
|---|---|---|---|
| XJ | All vehicles | 10.0 | 10.57 |
Note. Torque Specifications
| Description | Nm |
|---|---|
| Transmission retaining bolts | 48 |
| Transmission mount retaining bolts | 51 |
| Transmission fluid fill plug | A |
| Transmission control module (TCM) and main control valve body retaining bolts | 8 |
| Output shaft flange retaining nut | 60 |
| Torque converter retaining bolts | 62 |
| Transmission fluid cooler tube retaining bolt | 22 |
| Transmission fluid drain plug | 8 |
| Transmission fluid pan, gasket and filter retaining bolts | 8 |
| A = refer to the procedure for correct torque sequence |
TORQUE CONVERTER
| Item Number | Description |
|---|---|
| 1 | Impeller |
| 2 | Turbine |
| 3 | Stator |
| 4 | Freewheel clutch |
| 5 | Torque converter hub |
| 6 | Stator shaft |
| 7 | Turbine shaft |
| 8 | Drive plate |
| 9 | Journal - Drive plate/crankshaft location |
| 10 | Torque converter cover |
| 11 | Lock-up clutch piston |
| 12 | Lock-up clutch plate |
The torque converter is the coupling element between the engine and the transmission and is located in the bell 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 drive plate attached to the rear of the crankshaft.
The torque converter comprises 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 welded to the converter housing cover, the impeller is therefore driven at engine crankshaft speed.
The converter housing cover has four threaded bosses, which provide for attachment of the engine drive plate. The threaded bosses also provide for location of special tools which are required to remove the torque converter from the bell housing.
Impeller
Fluid Flow
| Item Number | Description |
|---|---|
| 1 | Turbine |
| 2 | Stator |
| 3 | Impeller |
When the engine is running the rotating impeller acts as a centrifugal pump, picking up fluid at its center and discharging it at high velocity through the blades on its outer rim. The design and shape of the blades and the curve of the impeller body cause the fluid to rotate in a clockwise direction as it leaves the impeller. This rotation improves the efficiency of the fluid as it contacts the outer row of blades on the turbine.
The centrifugal force of the fluid leaving the blades of the impeller is passed to the curved inner surface of the turbine via the tip of the blades. The velocity and clockwise rotation of the fluid causes the turbine to rotate.
Turbine
The turbine is similar in design to the impeller with a continuous row of blades. Fluid from the impeller enters the turbine through the tip of the blades and is directed around the curved body of the turbine to the root of the blades. The curved surface redirects the fluid back in the opposite direction to which it entered the turbine, effectively increasing the turning force applied to the turbine from the impeller. This principle is known as torque multiplication.
When engine speed increases, turbine speed also increases. The fluid leaving the inner row of the turbine blades is rotated in a counter-clockwise direction due to the curve of the turbine and the shape of the blades. The fluid is now flowing in the opposite direction to the engine rotation and therefore the impeller. If the fluid was allowed to hit the impeller in this condition, it would have the effect of applying a brake to the impeller, eliminating the torque multiplication effect. To prevent this, the stator is located between the impeller and the turbine.
Stator
The stator is located on the splined transmission input shaft via a freewheel clutch. The stator comprises a number of blades which are aligned in an opposite direction to those of the impeller and turbine. The main function of the stator is to redirect the returning fluid from the turbine, changing its direction to that of the impeller.
The redirected fluid from the stator is directed at the inner row of blades of the impeller, assisting the engine in turning the impeller. This sequence increases the force of the fluid emitted from the impeller and thereby increases the torque multiplication effect of the torque converter.
Stator Functions
| Item Number | Description |
|---|---|
| 1 | Blades |
| 2 | Stator held - fluid flow redirected |
| 3 | Stator rotates freely |
| 4 | Roller |
| 5 | Converter at coupling speed |
| 6 | Fluid flow from turbine |
| 7 | Converter multiplying |
| 8 | Fluid flow from impeller |
| 9 | Drive from engine |
| 10 | Impeller |
| 11 | Stator |
| 12 | Turbine |
| 13 | Output to transmission |
Fluid emitted from the impeller acts on the turbine. If the turbine is rotating at a slower speed than the fluid from the impeller, the fluid will be deflected by the turbine blades in the path 'A' . The fluid is directed at and deflected by the stator blades from path 'B' to path 'C' . This ensures that the fluid is directed back to the pump in the optimum direction. In this condition the sprag clutch is engaged and the force of the fluid on the stator blades assists the engine in rotating the impeller.
As the rotational speed of the engine and therefore the turbine increases, the direction of the fluid leaving the turbine changes to path 'D' . The fluid is now directed from the turbine to the opposite side of the stator blades, rotating the stator in the opposite direction. To prevent the stator from resisting the smooth flow of the fluid from the turbine, the sprag clutch releases, allowing the stator to rotate freely on its shaft.
When the stator becomes inactive, the torque converter no longer multiplies the engine torque. When the torque converter reaches this operational condition it ceases to multiply the engine torque and acts solely as a fluid coupling, with the impeller and the turbine rotating at approximately the same speed.
The stator uses a sprag type, one way, freewheel clutch. When the stator is rotated in a clockwise direction the sprags twist and are wedged between the inner and outer races. In this condition the sprags transfer the rotation of the outer race to the inner race which rotates at the same speed.
One Way Free Wheel Clutch - Typical
| Item Number | Description |
|---|---|
| 1 | Sprags |
| 2 | Inner race |
| 3 | Outer race |
| 4 | Sprag and cage assembly |
| 5 | Sprag outer race |
| 6 | Sprag inner race |
| 7 | Retaining ring |
The free wheel clutch can perform three functions; hold the stator stationary, drive the stator and free wheel allowing the stator to rotate without a drive output. The free wheel clutch used in the ZF 6HP28 transmission is of the sprag type and comprises an inner and outer race and a sprag and cage assembly. The inner and outer races are pressed into their related components with which they rotate. The sprag and cage assembly is located between the inner and outer races.
The sprags are located in a cage which is a spring which holds the sprags in the 'wedge' direction and maintains them in contact with the inner and outer races.
Referring to the illustration, the sprags are designed so that the dimension 'B' is larger than the distance between the inner and outer race bearing surfaces. When the outer race rotates in a clockwise direction, the sprags twist and the edges across the dimension 'B' wedge between the races, providing a positive drive through each sprag to the inner race. The dimension 'A' is smaller than the distance between the inner and outer race bearing surfaces. When the outer race rotates in an anti-clockwise direction, the dimension 'A' is too small to allow the sprags to wedge between the races, allowing the outer race to rotate freely.
On the illustration shown, when the outer race is rotated in a clockwise direction, the sprags twist and are 'wedged' between the inner and outer races. The sprags then transfer the rotation of the outer race to the inner race, which rotates at the same speed.
Lock-Up Clutch Mechanism
The torque converter clutch (TCC) is hydraulically controlled by an EPRS, which is controlled by the transmission control module (TCM). This allows the torque converter to have three states of operation as follows
- Fully engaged
- Controlled slip variable engagement
- Fully disengaged.
The torque converter clutch (TCC) is controlled by two hydraulic spool valves located in the valve block. These valves are actuated by pilot pressure supplied via a solenoid valve which is also located in the valve block. The solenoid valve is operated by pulse width modulation (PWM) signals from the transmission control module (TCM) to give full, partial or no lock-up of the torque converter.
| Item Number | Description |
|---|---|
| A | Unlocked condition |
| B | Locked condition |
| 1 | Clutch plate |
| 2 | Clutch piston |
| 3 | Torque converter body |
| 4 | Turbine |
| 5 | Impeller |
| 6 | Stator |
| 7 | Piston chamber |
| 8 | Turbine chamber |
The lock-up clutch is a hydro-mechanical device which eliminates torque converter slip, improving fuel consumption. The engagement and disengagement is controlled by the transmission control module (TCM) to allow a certain amount of controlled 'slip'. This allows a small difference in the rotational speeds of the impeller and the turbine which results in improved shift quality. The lock-up clutch comprises a piston and a clutch friction plate.
In the unlocked condition, the oil pressure supplied to the piston chamber and the turbine chamber is equal. Pressurized fluid flows through a drilling in the turbine shaft and through the piston chamber to the turbine chamber. In this condition the clutch plate is held away from the torque converter body and torque converter slip is permitted.
In the locked condition, the torque converter clutch (TCC) spool valves are actuated by the EPRS. The fluid flow in the unlocked condition is reversed and the piston chamber is vented. Pressurized fluid is directed into the turbine chamber and is applied to the clutch piston. The piston moves with the pressure and pushes the clutch plate against the torque converter body. As the pressure increases, the friction between the clutch plate and the body increases, finally resulting in full lock-up of the clutch plate with the body. In this condition there is direct mechanical drive from the engine crankshaft to the transmission planetary gear train.