Ring Gear, Adjusting
Drive Pinion and Ring Gear Adjusting
• General notes:
• Careful adjustment of the drive pinion and ring gear is important for the service life and smooth running of the final drive. For this reason, the drive pinion and ring gear are matched together during manufacture, and checked to ensure a good mesh pattern and quiet running in both directions of rotation. The position of quietest running is found by moving the drive pinion in an axial direction and at the same time lifting the ring gear out of the zero-play mesh position by the amount necessary to maintain the backlash within the specified tolerance.
• The object of the adjustment is to reproduce the setting for quietest possible running, as obtained on the test machine in production.
• The deviation "r", which is related to the master gauge " Ro" is measured for the final drive sets supplied as replacement parts and marked on the outer circumference of the ring gear. The final drive set (drive pinion and ring gear) must only be replaced together as a matched pair.
• Observe the general repair instructions for taper roller bearings and shims.
• Maximum care and cleanliness are essential for achieving good results when performing repairs and taking measurements.
Ring Gear, Adjusting
Adjusting Differential
Special tools, testers and auxiliary items required
• Magnetic plate 50 mm dia. (VW385/17)
• Dial gauge holder (VW387)
• Measuring lever (VW388)
• Adjustment tool for ring gear (VW521)
• Torque wrench (VAG1331)
It is necessary to readjust the ring gear when:
Final drive housing, cover for final drive, taper roller bearing for differential, differential housing or drive pinion are replaced.
Adjustment overview, refer to => [ Adjustment Overview ].
• Differential taper roller bearings are low friction bearings. Therefore the frictional torque only has a limited use as a check. Correct adjustment is only possible by determining the total shim thickness "S total".
• Do not oil new taper roller bearings for frictional torque measurement. The bearings have already been treated with special oil by the manufacturer.
Adjustment Shims S1 and S2, Determining Total Shim Thickness S Total
(Setting preload of taper roller bearing for differential)
• Drive pinion is removed!
• If only the taper roller bearings for the differential are being replaced, the ring gear can be removed from the differential housing. The pinion shaft does not need to be removed.
- Pry out seals for flange shaft using a suitable lever.
- Remove outer races of differential taper roller bearings and remove shims. Refer to => [ Differential ] Differential.
- Drive outer race/taper roller bearing for left differential (housing side) with shim "S2*" of thickness 1.00 mm into housing. Refer to => [ Differential ] Differential.
• For measurement purposes a shim "S2" with a thickness of 0.04 in is initially inserted. It is referred to as "S2*" in the following. After determining the backlash "S2*" will be replaced by the correct "S2".
- Drive outer race/taper roller bearing for right differential (cover side) without shim in onto stop. Refer to => [ Differential ] Differential.
- Insert differential into housing. The ring gear is positioned on the right side (cover side).
- Install cover and tighten bolts to 25 Nm.
- Install special tools (VW521/4) and ( 521/8) onto housing side in differential housing.
- Turn cover side of differential housing upward.
- Turn differential 8 turns in both directions so that the taper roller bearings settle.
- Place measuring plate (VW385/17) onto differential.
- Install measuring tools.
A - Dial indicator extension approximately 30 mm long
B - M8 x 45 bolt
- Position dial indicator extension in middle of measuring plate (VW385/17).
- Set dial indicator (3 mm measuring range) to "0" with 2 mm preload.
- Lift differential without turning; read off play on dial indicator and write it down.
• Measurement in following example: 0.50 mm
- If you want to repeat the measurement differential 8 turns in both directions so that the taper roller bearings settle.
Determining S Total
Shim S1, Determining Thickness
• The preliminary adjustment shim "S1*" will be replaced with the final shim "S1" after determining the backlash.
• The total shim thickness "S total" remains the same.
- Define shim(s) as precisely as possible based on the table.
Measuring Frictional Torque
• Pinion shaft removed
• Differential installed with shims "S1*" and "S2* "
- Install torque gauge 0 to 600 Nm - A - onto differential.
- Read off friction torque.
Frictional torque specified values:
* With at least 50 km service
• Differential taper roller bearings are low friction bearings. Therefore the frictional torque only has a limited use as a check. Correct adjustment is only possible by determining the total shim thickness "S total".
• Do not oil new taper roller bearings for frictional torque measurement. The bearings have already been treated with special oil by the manufacturer.
• If the final drive set is being readjusted, the adjustment of the pinion shaft should be performed now, and the adjustment should be checked => [ Drive Pinion, Adjusting ].
Adjusting Backlash
• Drive pinion with shim "S3" installed
• Differential with shims "S1*" + "S2*" installed
- Insert differential into final housing mount cover and tighten all bolts to 25 Nm.
- Turn differential 5 turns in both directions so that the taper roller bearings settle.
- Install measuring tools.
- Use dial indicator extension (VW382/10) (6 mm flat).
- Set measuring lever (VW388) to dimension " a" = 60 mm.
- Measure play between teeth flanks (backlash) as follows:
- Turn ring gear until it makes contact with a tooth flank (end of backlash travel).
- Preload dial indicator to 1 mm and set to zero.
- Turn ring gear back until lying against an opposite tooth flank (backlash).
- Read off backlash and note value.
- Turn ring gear through 90° and repeat measurements a further 3 times.
Backlash, Determining Average
• Result: The average backlash is 1.16 divided by 4 = 0.29 mm
• If the individual measurements differ by more than 0.06 mm from each other, the installation of the ring gear or the final drive set itself is not correct. Check installation; replace final drive set, if necessary.
Shim S2, Determining Thickness
- Determine shim(s) as accurately as possible from table.
Shim Table
* Using the shim tolerance variations it is possible to find the exact shim thickness required, insert two shims if necessary.
Shim S1, Determining Thickness
- Determine shim(s) as accurately as possible from table.
Shim Table
* Using the shim tolerance variations it is possible to find the exact shim thickness required, insert two shims if necessary.
Performing Measurement Check
• Drive pinion with shim "S3" installed
• Differential with shims "S1" (cover side) + "S2 "(housing side) installed
- Turn differential 5 turns in both directions so that the taper roller bearings settle.
- Measure backlash four times on circumference.
• Specification: 0.12 to 0.22 mm
• If the backlash is beyond the tolerance, the adjustments must be repeated. The total shim thickness "S total" must not be changed.
• The individual measurements must not differ by more than 0.06 mm from each other.