Ring Gear, Adjusting
Ring gear, adjusting
(Adjusting differential)
Special tools and equipment
^ VW 295 Drift
^ VW 382 Special socket and measuring tools
^ VW 385 Universal measuring tool
^ VW 387 Universal dial gauge holder
^ VW 388 Test lever
^ VW 402 Thrust plate
^ VW 459 Installation and removal tool
^ VW 521 Adjustment tool for ring gear
^ 30-205 Thrust plate
^ 30-505 Fitting mandrel
^ 3062 Thrust disc
^ Torque gauge 0 to 600 Ncm
^ Dial gauge
^ Dial gauge extension
It is necessary to readjust the ring gear when:
Transmission housing, cover for final drive, taper roller bearing outer race for differential, final drive housing or final drive set are replaced.
Adjustment overview
Determine total shim thickness "Stotal" (S1 plus S2)
(Setting preload of taper roller bearing for differential)
^ Drive pinion is removed.
- Pull out flanged shaft seal with VW 681.
- Remove outer races of differential taper roller bearings and remove shims.
- Drive outer race for taper roller bearing with shim S2 into transmission housing. For measurement purposes use a 1.20 mm thick S2* shim (2 shims of 0.60 mm).
Note: For measurement purposes a shim S2 with a thickness of 1.20 mm is inserted provisionally. It is referred to as S2* in the following. After determining the backlash, S2* is replaced by the final shim S2.
- Press taper roller bearing outer race without shim into cover for differential.
- Insert differential into housing without speedometer trigger wheel.
The side of the ring gear is positioned on the right side (cover side).
- Install cover and tighten bolts to 25 Nm.
- Turn transmission so that cover for differential faces up.
- 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.
- Position dial gauge extension in middle of measuring plate VW 385/17.
- Set dial gauge (3 mm measuring range) to zero with 2 mm preload.
A - Dial gauge extension 30 mm
- Move differential up and down with special tool VW 521 (direction of arrow).
- Read off play from dial gauge
Example:
0.62 mm
"Stotal" = S2* + reading obtained + pre load
Example:
Determining thickness of shim S1*
Notes:
^ After determining the backlash, provisional shim S1* is replaced by the final shim S1.
^ The total shim thickness "Stotal" remains the same.
S1* = Stotal - S2*
Example:
Note: Allocate shims using spare part catalog.
Adjusting backlash
Drive pinion inserted with S3 and S4
- Differential with ring gear: S1* is installed in the cover side, S2* in the transmission housing.
- Install final drive cover and tighten bolts to 25 Nm.
- Turn differential several times in both directions so that the taper roller bearings settle.
- Install measuring tools.
- Use dial gauge extension VW 382/10 (6 mm flat).
Set measuring lever VW 388 to dimension "a" = 79 mm.
- Turn ring gear to stop. Set dial gauge to zero, turn back ring gear and read off backlash. Note value.
- After turning ring gear through a further 90°, repeat measuring process a further 3 times. Add up the four measured values and calculate average backlash
Calculating average backlash
Example:
Center backlash = 1.96 mm: 4 = 0.49 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. Recheck the installation, and if necessary replace ring gear and pinion.
Determining shim thickness S2
(opposite ring gear)
S2* = Inserted shim(s)
- Average backlash
+ Lift (constant)
Lift = 0.15 mm
Example
Available shims for S2
Part numbers:
go to Parts catalog
- Different tolerances make it possible to obtain exact shim thickness required.
Determining adjustment shim thickness S,
(Ring gear side)
S1 = S total - S2
Example:
Available shims for S1
Part numbers:
go to Parts Catalog
- Different tolerances make it possible to obtain exact shim thickness required.
Install determined shims, S1 on the ring gear side, S2 opposite ring gear, use 2 shims if necessary.
Performing check measurement
Measuring backlash
- It must be 0.12 to 0.22 mm.