Drivelines

DESCRIPTION
Driveline angularity is the angular relationship between the engine crankshaft, the driveshaft and the rear axle pinion. Factors determining driveline angularity include ride height (rear spring) and engine mounts.

An incorrect driveline (pinion) angle can often be detected by the driving condition when vibration occurs.
- A vibration during coasting from 72 to 56 km/h (45 to 35 mph) is often caused by a high pinion angle.
- A vibration during acceleration, again around 56 to 72 km/h (35 to 45 mph), may indicate a lower-than-specified pinion angle. Refer to the following procedure to check driveline angle.

NOTE: Driveline angles are given in relation to a 0-degree longitudinal (fore-aft) unibody frame rail angle and are specified for individual components.

PROCEDURE
1. Raise the vehicle on a drive-on type hoist or back onto a front-end alignment rack. Bounce the vehicle to normalize the suspension. This ensures that the suspension components are in the normal-load condition.





2. Measure the ride height. The vehicle must be in the curb height (empty) condition. Find the recorded ride height in the Rear Driveline Angles charts. The specified driveline angles correspond to the measured ride height.
3. Driveline angles are measured with Pinion Angle Level Gauge T68P-4602-A or with an adjustable bubble (spirit level) protractor. The protractor is used when the tool kit is not available or when the angles to be measured are more than 12 degrees. All angles should be read within 1/2 degree with the tool or protractor held plumb on a clean, flat surface.





4. Place the vee magnet of Pinion Angle Level Gauge T68P-4602-A on the bottom of the vehicle frame as shown and calibrate the tool to a zero bubble reading. This gives the O-degree frame angle. Average the readings from both sides to obtain a more accurate reading.





5. Check the engine angle by rotating the driveshaft until one transmission slip-yoke ear is parallel to the floor. Remove the retaining snap ring, if so equipped, from the yoke. Install the pinion angle level gauge and record the angle reading. If the angle reading differs from the specified angle by 1 degree or more, neutralize the engine and transmission mounts. With the engine angle at specifications, check the driveshaft and pinion angles. Reinstall the snap ring.





6. To check the driveshaft angle, rotate the driveshaft so one driveshaft yoke ear is parallel to the floor. Remove the retaining snap ring, if so equipped, from the yoke. Install the magnetic pinion angle level gauge on the U-Joint bearing cup and record the angle reading. Reinstall the snap ring. Check the pinion angle and if either or both readings are not to specification, adjust as necessary.





7. To check the pinion angle, rotate the driveshaft so that one ear of the rear axle yoke is parallel to the floor. Install the Pinion Angle Level Gauge and record the reading. If the reading is not to specifications, adjust as necessary.








8. To check driveline angle with adjustable bubble (spirit level) protractor, follow Steps 1 and 2 to normalize suspension and measure ride height. Place the protractor on the bottom of the vehicle frame directly below the front driver/passenger seat. This gives the 0-degree frame angle. Take and average the readings from both sides to obtain a more accurate reading.

NOTE: When using a bubble (spirit level) protractor, the angles are read from the 0-degree frame angle. The 90-degree mark on the protractor is read as the 0-degree frame angle. For example, when the protractor is placed vertically on the component and the protractor reads 85 degrees, the component angle is actually +/-5 degrees.

9. To check the engine angle, rotate the driveshaft until one transmission slip-yoke ear is parallel to the floor. Place the protractor so it is flush against the slip-yoke ear.

NOTE: If slip-yoke ears are not machined, rest the protractor against bottom of starter motor.





10. Make sure the protractor is not resting against any portion of the driveshaft. Record the angle reading. If the engine angle reading differs from the specified angle by 1 degree or more, proceed to Engine Angle Adjustments and normalize the engine and transmission mounts. With the engine angle at specifications, check the driveshaft and pinion angles.
11. To check the driveshaft angle, place the protractor on any portion of the driveshaft tube so the plane surface of the protractor is flush against the bottom surface of the tube and parallel to the floor.





12. Record the reading. Subtract frame angle to get driveshaft angle. Check the pinion angle and if both or either reading is not to specifications, adjust as necessary.





13. To check the pinion angle, place the protractor in a vertical position so it is flush against two axle housing cover retaining bolts. Rotate the protractor bubble indicator so the 90-degree marks align with the indexing marks. Read the protractor and calculate angle. For example, if the protractor indicates a reading of 85 degrees, the pinion angle reading is +/-5 degrees. Record the reading. If the reading is not to specification, adjust as necessary.
14. Road test to verify resolution of condition. If driveline angle correction and driveline runout/balance procedures do not eliminate the vibration condition, the differential ring gear and pinion should be checked for backlash variation.





15 Remove the axle housing cover. Measure ring gear backlash on 30 consecutive ring gear teeth using Dial indicator with Bracketry TOOL-4201-C or equivalent and note the variation between the high and low readings. If over 0.10 mm (0.004 inch), replace the differential ring gear and pinion.