The test consists of determining the critical engine speed at full throttle and shift lever positions "D" And "R". This test tests the operation of the torque converter stator freewheel and the holding capacity of the transmission and low and reverse brake clutches.
Warning. During this test, make sure that no one is in front of or behind the vehicle.
1. Check the fluid level in the gearbox. Fluid must be at normal operating temperature (80-90°C). Engine coolant should also be at normal operating temperature (80-90°C).
2. Install chocks under both rear wheels.
3. Attach a tachometer to the engine.
4. Fully apply the parking and service brakes.
5. Start the engine.
6. With the shift lever in position "D", fully depress the accelerator pedal to fix the maximum engine speed. Do not hold the throttle wide open for longer than is necessary to obtain maximum engine speed, and never for more than 5 seconds at a time. If more than one test is required, run the engine for about 2 minutes in neutral at about 1000 rpm to cool the transmission fluid between tests.
- Critical speed during testing - 2300-2700 rpm
7. Set the shift lever to the position "R" and test as described above.
Critical speed is above normal when the lever is in position "D"
If the critical speed is above normal, there is slippage in the rear clutch or overrunning transmission clutch. In this case, carry out a hydraulic test to determine the cause of slippage.
Critical speed is above normal when the lever is in position "R"
If the parking critical speed is above normal, there is slippage in the transmission front clutch or low and reverse brake. In this case, carry out a hydraulic test to determine the cause of slippage.
Critical speed below normal at positions "D" And "R"
If the critical speed is below normal, it can be assumed that the engine power is insufficient or the torque converter is malfunctioning. Check for misfiring in the engine, correct ignition timing, valve clearances, etc. If everything is in order in the engine, the torque converter is faulty.