When Servicing Full-Time 4WD Vehicles
WHEN SERVICING FULL-TIME 4WD VEHICLESa. BEFORE BEGINNING TEST
NOTE: Tester with a function of 2-wheel load setting (2-wheel power absorption type) cannot be used; such as a 2-wheel chassis dynamometer, and a combined tool of a 2-wheel chassis dynamometer, a speedometer tester and a brake tester.
b. BRAKING FORCE TEST (Vehicle speed: 0.5 km/h or 0.3 mph)
When performing measurement with a low-speed type brake tester, observe the following instructions.
1. Position the wheels to be tested (front or rear) on the rollers.
2. Set another wheels free by free rollers or safety stands.
3. Shift the transmission shift lever into the "N" range.
4. Fasten the vehicle with lock chains.
5. Idle the engine, and perform measurement by driving the tester rollers.
NOTE:
- Tester with a function of load measurement cannot be used.
- High-speed type brake tester cannot be used.
c. SPEEDOMETER TEST OR OTHER TESTS (Using speedometer or chassis dynamometer) When performing test, use the method shown.
1. Place the front wheels onto the rollers.
2. Set the rear wheels free with free rollers or safety stands.
3. Fasten the vehicle with lock chains.
4. Start the engine, and then measure the vehicle speed by increasing the speed gradually in the "D" range.
5. After the measurement completion, decrease the vehicle speed with brake gradually, and then stop the vehicle.
NOTE:
- Inspection should be performed in the front wheels.
- Do not start, accelerate or decelerate the vehicle suddenly.
- Maximum vehicle speed must be below 60 km/h or 37 mph (when using a free roller, it must be below 50 km/h or 31 mph).
- Driving time for the test should be within 1 minute.
HINT: Only the tests of No.3 and No.4, shown in the table, can have a high-speed test or heavy load test.
NOTE:
- Confirm that the vehicle is securely immobilized.
- Never operate the clutch or brakes, and never drive the wheels or decelerate suddenly.
- Be sure to strictly follow the above procedure for the test, because functions of 4WD system might fail, parts of driving system might malfunction, or the vehicle might unexpectedly jump out.
d. ON-VEHICLE WHEEL BALANCING MEASUREMENT
When doing on-vehicle wheel balancing measurement on a full-time 4WD vehicle, to prevent the wheels from rotating at different speeds in different directions from each other (which could damage the center differential), always be sure to observe the following precautions:
1. Jack up all the 4 wheels with a 2-post-type lift.
All the 4 wheels should be jacked up, clearing the ground completely.
2. Fasten the vehicle by setting 2 pick-up stands in the bottom of the suspension arm's tip of the front wheels or rear wheels to be measured.
3. Support the vehicle with safety stands so that the vehicle will not lean in the vehicle's front/rear direction.
4. Release the parking brake.
5. Check that no dragging force exists by turning each wheel by hand.
6. Set the wheel balancers.
7. Measurement should be performed by using both of the engine drive and wheel balancer roller drive.
NOTE:
- Start the engine, and then increase the vehicle speed gradually in the "D" range.
- Do not accelerate or decelerate suddenly.
- Deceleration should be performed by brake gradually.
- Take special care so that the vehicle will not move.
- Measurement should be performed quickly.