Using Universal Gauge VW-385
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
1 - Deviation "r" in 1/100 mm
2 - Mating number
- Determine adjustment value E from known design value R = 66.30 mm by adding deviation "r" which is shown on pinion face.
Example:
The pinion face shows deviation "r" to be N 10
R = Design value 66.30 mm
r = Deviation + 0.10 mm
_____________
E = Adjustment value = 66.40 mm
- Assemble gear cluster without selector forks or adjustment shims.
- Tighten preload plate nuts to specified torque.
^ Torque to: 24 Nm (17.7 ft lb)
NOTE: The collar nut on the pinion shaft must be tightened to specified torque prior to measuring.
- Fasten gear housing with 2 nuts.
- Install free gear of 5th speed together with spider. Block pinion shaft with clamp P 37a. Engage 4th speed and tighten collar nut to specified torque.
^ Torque to: 250 Nm (184 ft lb)
- Make sure that outer races of bevel roller bearings are firmly seated in gear housing and housing side cover.
- Move adjustable collar on setting gage VW 385/1 to dimension "a".
a = 52 mm
1 = VW 385/1 Setting gage shaft
2 = VW 385/4 Gage block
3 = VW 385/14 Gage contact plunger
4 = VW 385/53 Gage contact extension
5 = VW 385/52 Master plate
6 = --- Dial indicator
- Slide gage blocks VW 385/4 onto the setting gage shaft and screw contact plunger VW 335/14, together with the contact extension VW 385/53 (14 mm), into place.
NOTE: Turn adjustable collar back to stop.
- Place master plate VW 385/52 (R = 66.3O mm) in position and adjust dial indicator (3 mm range) to 0 under a 1 mm preload (small pointer on 1, long pointer on 0).
- Remove master plate and place setting gage in gear housing, making sure that the dial indicator extension is oriented towards the setting pad.
- Insert housing side cover (without O-ring) and tighten nuts to specified torque.
^ Torque to: 24 Nm (17.7 ft lb)
CAUTION: Never use a hammer when installing the housing side cover. This may cause the magnetically attached setting pad to fall off the pinion. Bring side cover into proper place only by evenly tightening the retaining nuts.
- Using the spindle, pull the second gage block so far outwards that the setting gauge shaft can still be barely turned.
- Carefully turn setting gage until the gauge contact extension is positioned perpendicular to the pinion shaft face. In this instance, the indicator shows the highest reading which is to be noted.
- Observe the following points when reading the dial indicator:
^ The design value R = 66.30 mm was set by means of the master plate VW 385/52.
^ If the value indicated on the gage deviates clockwise from the set design value (R = 66.30 mm), then the dimension is smaller than 66.30 mm, that is, the amount of deviation from 0 must be subtracted from the value of 66.30 mm.
Example:
The small pointer on the indicator is between 1 and 2, and the long pointer shows 0.29 mm.
Adjusted design value
(master plate VW 385/52) 66.30 mm
Measured value - 0.29 mm
____________
Distance to pinion shaft face = 66.01 mm
Adjustment value (example) 66.40 mm
Distance to pinion shaft face - 66.01 mm
____________
Shim thickness = 0.39 mm
- This means that the pinion shaft must be moved away from the ring gear center by 0.39 mm.
- This is accomplished by installing two 0.20 mm thick shims (end values of 3 or more should be rounded off to 5, and from 7 on to 10).
- Recheck adjustment value E (shown as 66.40 mm in the example) upon installation of shims; a deviation of ± 0.03 mm is permissible.
- A tooth contact pattern test need not be performed.
NOTE: If the shims were selected in proper thickness, the dial indicator must show the value of deviation "r" (shown in the example as 0.10 mm) within a tolerance of ± 0.03 mm during the recheck.