Ring Gear, Adjusting
Ring gear, adjusting
Special tools and workshop equipment required:
(Adjusting differential)
^ VW 385/17 Magnetic plate 50 mm dia.
^ VW 387 Dial gauge holder
^ VW 388 Measuring lever
^ VW 521 Adjustment tool for ring gear
^ V.A.G 1331 Torque wrench
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.
Note:
^ 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 "Stotal".
^ Do not oil new taper roller bearings for frictional torque measurement. The bearings have already been treated with special oil by the manufacturer.
Determining total shim thickness "Stotal" for shims "S1" + "S2"
(Setting preload of taper roller bearing for differential)
^ Drive pinion is removed!
Note: 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
- Drive outer race/taper roller bearing for left differential (housing side) with shim "S2" of thickness 1.00 mm into housing.
Note: 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.
- 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 VW 521/4 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 VW 385/17 onto differential.
- Install measuring tools.
A - Dial indicator extension approximately 30 mm long
B - Hex bolt M8 x 45
- Position dial indicator extension in middle of measuring plate VW 385/17.
- 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.
Determine "Stotal" (S1 + S2)
Determining thickness of shim "S1"
Note:
^ The preliminary adjustment shim "S1"will be replaced with the final shim "S1" after determining the backlash.
^ The total shim thickness "Stotal" remains the same.
- Define shim(s) as precisely as possible based on the table.
Measuring frictional torque (check)
^ Pinion shaft removed
^ Differential installed with shims "S1" and "S2"
- Install torque gauge 0 to 600 Ncm -A- onto differential.
- Read off friction torque.
Frictional torque specified values:
Note:
^ 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 "Stotal".
^ 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 re-adjusted, the adjustment of the pinion shaft should be performed now, and the adjustment should be checked.
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 VW 382/10 (6 mm flat).
- Set measuring lever VW 388 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.
Determining average backlash
^ Result: The average backlash is 1.16 divided by 4 = 0.29 mm
Note: If the individual measurements differ by more than 0. 06 mm from each other, the installation of the ling gear or the final drive set itself is not correct. Check installation, replace final drive set, if necessary.
Determining thickness of shim "S2"
- Determine shim(s) as accurately as possible from table.
The following shims are available for "S2"
Determining thickness of shim "S1"
- Determine shim(s) as accurately as possible from table.
The following shims are available for "S1"
Check measurement
^ 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
Note:
^ If the backlash is beyond the tolerance, the adjustments must be repeated. The total shim thickness "Stotal" must not be changed.
^ The individual measurements must not differ by more than 0.06 mm from each other.