Using P 258 Mandrel
Explanation of AdjustmentAdjustment of the ring gear and pinion is important for quiet operation of the rear axle assembly. For this reason the pinion shaft and ring gear are already matched as a pair during production. They are checked on testing machines for correct contact pattern and low noise level in both directions of rotation. When the ring gear and pinion is tested, it is set according to the design dimension "R". Dimension "R" is the distance from the face of the pinion to the ring gear center line. The pinion is then moved in or out of mesh until the quietest operation is determined. The deviation from the design dimension (the in or out movement of the pinion) is called "r" and is etched on the face of the pinion. While making this test, the ring gear backlash is kept within a tolerance of 0.12 - 0.18 mm. The ring gear and pinion shaft is designed in such a way that the deviation "r" must always be added to the design dimension "R".
Earlier pinion assemblies had either a plus (+) or a minus (-) etched in front of the deviation "r" whereas on the newer pinion assemblies, the letter "N" precedes the deviation "r" on the pinion shaft.
Ring gear and pinion shaft sets are also stamped with a matching set number and should always be replaced as a complete set.
R - Design Dimension (66.30 mm)
r - Deviation from design dimension, shown in 1/100 mm
1 - Deviation r
2 - Matching set number
3 - Backlash
Adjusting Pinion Shaft
- By adding the design dimension "R" and the deviation "r" you get the adjusting dimension "E". Dimension "E" is the distance from the ring gear center line to the face of the pinion at which the ring and pinion set has been found to operate best.
Example:
The pinion shaft face end shows the deviation "r" to be 0.02 mm.
R = Design dimension 66.30mm
r = Deviation + 0.02mm
___________
E = Adjusting dimension = 66.32mm
- After finding the "Adjusting dimension E", attach input and pinion shafts, without shims, to final drive housing with clamping plates.
CAUTION: Tighten flange nut on input shaft to correct torque before making any measurements.
- Install plate P 260 a.
- Assemble 5th speed gears with synchro hub and shifting sleeve.
- Engage 5th gear. Block input shaft with holder P 37a and torque flange nut.
^ Torque to: 250 Nm (184 ft lb)
- Place mandrel P 258 on gauge block P 258a.
- Attach dial gauge to mandrel with a 1 mm preload.
- Install mandrel P 258, with tapered roller bearings, in the differential housing so that there is an axial preload of approx. 0.1 mm when the side cover is installed. The mandrel should not have axial play during the measurement. Play can be eliminated by using differential shims.
CAUTION: Make sure the dial indicator sensor does not point into the center bore of the pinion shaft.
- Rotate the mandrel carefully until the sensor forms a right angle with the face of the pinion. At this point the dial indicator will show the highest reading. A notch on the end of the mandrel shows the position of the dial indicator sensor.
- Record the reading.
- Note the following when reading the dial indicator:
^ The distance from the center line of the mandrel to its resting base is shown on the side of the mandrel.
^ The distance from the measuring surface of the gauge block to its support surface is indicated on the side of the gauge block.
- By adding the mandrel and gauge block dimensions the "actual adjusting dimension" is obtained.
Example:
Mandrel dimension 54.015 mm
Gauge block dimension + 12.595 mm
______________
Actual adjusting dimension = 66.610 mm
- If the pointer reads to the right (clockwise). the distance is smaller than the "actual adjusting dimension" (66.61 mm). Therefore subtract the dial indicator reading from the "actual adjusting dimension" to determine the distance from ring gear center to face of pinion.
Example:
Actual adjusting dimension 66.61 mm
Dial indicator reading - 0.39 mm
_____________
Distance from ring gear
center to face of pinion = 66.22 mm
Dimension "E"
(from the first example) 66.32 mm
Distance from ring gear
center to face of pinion + 66.22 mm
_____________
Shim thickness = (0.10 mm)
- The pinion shaft must therefore be moved away from the ring gear center by 0.10 mm.
- This can be achieved by inserting a 0.10 mm thick shim. (End numbers from 3 or more should be rounded off to 5, and from 7 or more to 10).
- Should the dial indicator read clockwise, the deviation when added to the "actual adjusting dimension" (mandrel dim. + gauge block dim.) should not exceed 0.03 mm.
- Shims are available in the following thicknesses: 0.10, 0.15, and 0.20 mm. Total thickness of shims must not exceed 0.50 mm.
- Adjusting dimension "E" should be rechecked after shims have been installed.
- A deviation of 0.03 mm is permissible.
- It is not necessary to check the gear tooth contact pattern.
Measuring Total Spacer Thickness for Ring Gear
- Make sure that side bearing outer races are fully seated in the housing and side cover.
- Install a 3.5 mm spacer (S1) on the ring gear side beneath the side bearing.
- Install a 3.0 mm spacer (S2) on the opposite side beneath the other bearing.
- Install differential with side bearings in housing and install side cover without 0-ring and without oil seal. Do not tighten.
- Lightly tighten the side cover using two nuts opposite each other. This preloads the side bearings.
- Check the gap between the cover and housing with a feeler gauge. The nominal value for the side bearing preload is 0.30 to 0.40 mm.
- If the nominal value of 0.30 to 0.40 mm is not reached, replace the (S1) spacer (ring gear side) with an appropriate spacer.
Example:
Feeler gauge measurement 0.65 mm
Nominal value for side
bearing preload (0.40 mm) - 0.40 mm
____________
Spacer thickness required = 0.25 mm
- The installed spacer S1 (3.5 mm) must therefore be replaced with one 0.25 mm thinner, that is, it should be 3.25 mm thick.
- Tighten side cover to correct torque.
- Place washer from special tool P 357 on the U-axle flange. Install the axle flange. Slightly tighten the expansion bolt.
CAUTION: When measuring differential drag, the pinion shaft must be disengaged and the axle flange oil seal must be removed from the side cover to prevent additional drag.
- Measure drag of the assembled differential with a torque wrench. The following values must be obtained to ensure proper side bearing preload.
^ SKF bearings = 300 to 420 Ncm (26 37 in. lb)
^ FAG bearings = 350 to 650 Ncm (30 - 56 in. lb)
- If the differential drag is not within tolerance, replace the spacer washer.
- Remove differential. Then pull off both side bearings.
CAUTION: Do not interchange spacer washers after removal.
- Measure the thickness of both spacers with a micrometer. Add these measurements to obtain the total thickness of the spacers for ring gear adjustment.
NOTE: In order to check backlash correctly (a subsequent procedure). the spacer S1 should be 0.1 mm (0.004 in.) thinner than one half of the sum of spacers S1 and S2. The spacer S2 should be 0.1 mm (0.004 in.) thicker than one half of the sum of spacers S1 and S2.
Example:
Total thickness of spacers (S1 + S2) = 6.25 mm
6.25 mm x 0.5 = 3.125 mm
3.125 mm - 0.10 mm = 3.025 (Thickness of spacer S1)
6.25 mm x 0.5 = 3.125 mm
3.125 + 0.10 mm = 3.225 (Thickness of spacer S2)
- Spacers are available in increments of 0.10 mm from 2.4 to 3.7 mm.
- A shim, 0.25 mm thick, permits adjustments to the nearest 0.05 mm. The rounded off spacer thickness should not differ from the calculated spacer thickness.
Example:
Calculated spacer thickness:
S1 + S2 = 3.025 + 3.225 = 6.25 mm
Rounded off spacer thickness:
S1 + S2 = 3.0 + 3.25 = 6.25 mm
- Before measuring, remove any burr that may be on the edges of the spacer.
- Measure the thickness of the two spacers with a micrometer at four different points; the thickness tolerance is 0.02 mm (0.008 in.).
ADJUSTING RING GEAR BACKLASH
- Install gear cluster with shims determined at time of pinion shaft adjustment.
CAUTION: Make sure pinion shaft flange nut is tightened to correct torque before making any adjustments.
^ Torque to: 250 Nm (184 ft lb)
- Install differential with side bearings and correct shims (S1 and S2).
- Install side cover with oil seal. Apply light coat of oil to seal.
CAUTION: When tightening the nuts. take care that a certain amount of side clearance exists. Make sure the pinion shaft does not jam.
- Tighten side cover bolts to correct torque.
^ Torque to: 24 Nm (17.7 ft lb)
- Block pinion shaft with holder P 259a.
- Place washer from special tool P 357 onto the axle flange. Attach dial indicator with sensor P 259b. Bolt dial indicator holder over the axle flange with the 10 x 110 mm bolt. The dial indicator should have a slight preload.
- Move dial indicator holder back and forth. Read backlash on dial indicator.
- Turn ring gear about 90° and measure backlash again. The readings must not vary by more than 0.05 mm.
CAUTION: The accurate backlash is marked on the ring gear.Backlash tolerance: 0.12 to 0.18 mm.
- Spacers S1 and S2 can be replaced with special tools P 263 and P 264b until proper backlash is attained. Be sure that the total spacer thickness is not changed.