Ring Gear, Adjusting
Ring gear, adjusting
(Adjusting differential)
Repairs after which the ring gear has to be adjusted, Refer to Differential, Assembly, Adjustments
Note:
^ Differential tapered roller bearings are low friction bearings. Therefore the friction torque only has a limited use as a check. Correct adjustment is only possible by determining the total shim thickness "Stotal."
^ Do not additionally oil new tapered roller bearings for friction torque measurement. The bearings have already been treated with a special oil by the manufacturer.
Determining total shim thickness "Stotal" for shims "S1" + "S2"
(Setting preload of tapered roller bearing for differential)
Drive pinion removed or ring gear dismantled from differential housing
- Pull out drive flange oil seal with lever.
- Remove differential tapered roller bearing outer races and take out shims, Refer to Differential, Assembly, Service and Repair.
Press outer race of left tapered roller bearing for differential (housing side) with shim "S2" into housing
Refer to Differential Service and Repair, See Fig. 2,. To perform measurement use a shim "S2*" with a thickness of 1.00 mm (one 0.80 mm shim and one 0.20 mm shim).
Note: For measurement purposes a shim "S2" of 1.0 mm is initially inserted which will be designated "S2*" in the following. After determining the backlash "S2*" will be replaced by the correct "S2.."
- Press in outer race of right tapered roller bearing for differential (final drive cover side) without shims
, Refer to Differential, Assembly, Service and Repair, See Fig. 8, (install as far as the stop).
- Insert differential into housing. Ring gear is positioned on right side (cover side).
- Fit 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 5 turns in both directions to settle tapered roller bearing.
- Place measuring plate VW 385/17 onto differential.
- Fit measuring tools.
A- Dial gauge extension approximately 30 mm long
B - Hex bolt M8 45
- Place D.T.I. extension on center of measuring plate VW 385/17.
- Set dial gauge (3 mm measuring range) to "0" with 2 mm preload.
- Lift differential without turning; read play on dial gauge and note.
Measurement in following example: 0.50 mm
Note: If the measurement has to be repeated, the differential must again be turned 5 turns in each direction to settle the tapered roller bearing.
Formula: Stotal = S2*" + measurement + bearing preload
Example: Inserted shim(s) "S2*" 1.00 mm
+ Measured value 0.50 mm
+ Bearing preload (constant) 0.30 mm
, Refer to Total shim thickness Stotal for shims "S1" + "S2" 1.80 mm
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 unchanged.
Formula: S1 , = Stotal - S2
Example: Total shim thickness Stotal for shims "S1" + "S2" 1.80 mm
- Inserted shim(s) "S2*" 1 .00 mm
= Thickness of shim "S1*" 0.80 mm
- Determine shim(s) as accurately as possible from table, Refer to Differential Assembly, Adjustments.
Measuring friction torque (check)
Drive pinion removed
Differential fitted with shims "S1*" and "S2*"
- Fit torque gauge 0-600 Ncm -A- onto differential.
- Read friction torque.
Friction torque specifications:
1) run at least 50 km (30 miles)
Note:
^ Differential tapered roller bearings are low bearings. Therefore the friction torque only has a limited use as a check. Correct adjustment is only possible by determining the total shim thickness Stotal.
^ Do not additionally oil new tapered roller bearings for friction torque measurement. The bearings have already been treated with a special oil by the manufacturer.
^ If the final drive set (drive pinion and ring gear) is being re-adjusted, the adjustment of the drive pinion should be performed now, and the adjustment checked, Refer to Differential Assembly, Adjustment
Adjusting backlash
(Positioning ring gear in final drive housing)
Drive pinion with shim "S3" installed
Differential with shims "S1*" + "S2*" installed
- Insert differential in final drive housing, install cover and tighten all bolts to 25 Nm.
- Turn differential 5 turns in both directions to settle tapered roller bearings.
- Assemble measuring equipment.
Use dial gauge extension VW 382/10 (6 mm flat).
- Set measuring lever VW 388 to dimension "a" , = 60 mm.
- Determine play between teeth flanks as follows:
- Turn ring gear until it makes contact with a tooth flank (end of backlash travel).
- Set dial gauge to "0" with 1 mm preload.
- Turn ring gear back until lying against an opposite tooth flank (backlash).
- Read backlash and note value.
- Turn ring gear through 90° and repeat measurements a further 3 times.
Note: 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.
Determining average backlash
Example:
1st measurement 0.28 mm
+ 2nd measurement 0.30 mm
+ 3rd measurement 0.30 mm
+ 4th measurement 0.28 mm
, Refer to Sum of measured values 1.16 mm
Result: The average backlash is 1.16 + 4, = 0.29 mm
Determining thickness of shim "S2"
Formula:
"S2" ,= "S2*" - backlash lift
Example:
Inserted shim "S2*" 1.00 mm
Average backlash 0.29 mm
+ Lift (constant) 0.15 mm
, Refer to Thickness of shim "S2" 0.86 mm
- Determine shim(s) as accurately as possible from table.
Refer to Parts Supplier
The following shims are available for "S2"
1) Using the shim tolerance variations it is possible to find the exact shim thickness required, insert two shims if necessary.
Determining thickness of shim "S1"
Formula:
S1 = Stotal - S2
Example:
Total shim thickness "Slogan" for 1.80 mm "S1" + "S2"
-Thickness of shim "S2" 0.86 mm
=Thickness of shim "S1" 0.94 mm
Determine shim(s) as accurately as possible from table. Part numbers
Refer to Parts Supplier
The following shims are available for "S1"
1) Using the shim tolerance variations it is possible to find the exact shim thickness required, insert two shims if necessary.
Performing check measurement
Drive pinion with shim "S3" installed
Differential with shims "S1" + "S2" installed
- Turn differential 5 turns in both directions so that tapered roller bearings settle.
- Measure backlash four times on circumference.
^ Specifications: 0.12 - 0.22 mm
Note:
^ If the backlash lies outside the tolerances, the adjustments must be repeated, but the total shim thickness "Stotal" must remain unchanged.
^ The individual measurements must not differ by more than 0.06 mm from each other.