Pic. 13.26. Clutches and brakes for automatic transmission
Warning. No one should stand in front of or behind the vehicle while testing.
1. Before testing, check the levels of all operating fluids and, if necessary, bring them to normal levels.
- The transmission fluid level should be near the HOT mark on the gauge.
- The transmission fluid temperature should be between 70-80°C.
- Coolant temperature 80-100°C.
2. Place chocks under the rear wheels.
3. Apply the parking brake and depress the brake pedal.
4. Start the engine.
5. Move the selector lever to position D. Press the brake pedal with your left foot, and gently press the accelerator pedal with your right foot. When the engine speed no longer increases, read the tachometer and release the accelerator pedal.
Warning
- (1) To avoid damage to the gearbox, test for 8 seconds.
- (2) If it is necessary to carry out more than one test with the engine running, move the selector lever to position N and leave it to operate at a speed of 1000 rpm-1 until the transmission fluid cools down.
Engine speed when testing the combined operation of the automatic transmission and the engine on a stationary vehicle (stall test): 2200-2700 min-1
6. In the same way, test in position R of the selector lever.
Engine speed when testing the combined operation of the automatic transmission and the engine on a stationary vehicle (stall test): 2200-2700 min-1
Analysis of test results
1. Engine speed is above specification in selector lever positions D and R.
- Low pressure in the pipeline.
- Brake slip in low gear and reverse gear.
2. Engine speed is above specification only in selector lever position D.
- Underdrive clutch slip.
3. The engine speed is above specification only in the R position of the selector lever.
- Reverse clutch slip.
4. Engine speed is below specification in D and R positions of the selector lever.
- Torque converter damage.
- Insufficient engine power