Ring Gear, Adjusting
RING GEAR, ADJUSTING
(Adjusting differential)
Special tools and equipment
^ VW385/17 Magnetic plate
^ VW387 Dial gauge holder
^ VW388 Measuring lever
^ VW521 Adjusting device
It is necessary to readjust the ring gear when the final drive housing, final drive cover, differential tapered roller bearings, differential housing or the pinion and ring gear are replaced.
Adjustment overview. Testing and Inspection
Calculating total shim thickness S_total (S1 plus S2).
(Adjusting tapered roller bearings for the differential)
^ Pinion removed!
Note: To replace the tapered roller bearings for the differential, only the ring gear needs to be removed from the differential housing. The pinion does not need to be removed.
- Pry out drive flange seal using assembly lever.
- Remove differential tapered roller bearing outer race and remove shims. Service and Repair
- Press small tapered roller bearing outer race together with 1.00 mm thick shim up to stop in housing (S2 side). Service and Repair
- Install differential in housing.
Ring gear is positioned on cover side
- Install cover and tighten bolts to 25 Nm (18 ft. lbs.).
- Attach special tool to transmission housing side on differential housing.
- Turn final drive such that cover side is upward.
- Turn differential 8 turns in both directions, so that tapered roller bearings settle.
- Install measuring tools.
- Place VW385/17 magnetic plate on differential.
A - Dial indicator extension 30 mm
- Install bolt -B- (M8 x 45).
- Place dial indicator extension on center of VW385/17 magnetic plate.
- Set dial indicator (3 mm measuring range) to zero with 2 mm preload.
- Move differential up and down (direction of arrow) without turning.
- Read off play from dial indicator.
Example
Play from dial indicator = 0.50 mm
Calculating "S_total" (S1 + S2)
"Total" = Dial indicator reading + preload
- If it is necessary to repeat measuring sequence, turn differential 8 turns in both directions, so that tapered roller bearings settle.
The specified bearing preload is obtained by adding a constant preload figure (0.30 mm)to the reading obtained (0.50 mm) and the thickness of the shim installed (1.00 mm).
Example
- Install calculated total shim thickness (1.80 mm in example) behind tapered roller bearing outer race in transmission housing (S2 side).
Determining shim S1 thickness
Shim S1 installation position: same side as the ring gear
Note: The temporary shim "S" will be changed for the correct shim "S1" after determining the backlash.
Example
Different tolerances make it possible to select exact thickness of shim(s) required.
- Install correct shim S1 on ring gear side, and S2 opposite of ring gear, if necessary install 2 shims.
Adjusting backlash
^ Pinion installed with S3
^ Differential: Total (S1 + S2) installed in transmission housing
- Install final drive cover and tighten bolts to 25 Nm (18 ft. lbs.).
- Turn differential several times in both directions so that tapered roller bearings settle.
- Install measuring tools.
Use VW382/10 extension pin (6 mm flat) for dial indicator.
- Set VW388 measuring lever to 60 mm (dimension -a-).
- Turn ring gear to stop. Set dial indicator to zero with 1 mm preload,turn ring gear back and read off backlash. Note reading.
- Repeat measurement three times, turning ring gear through 90° each time. Add four results and calculate average backlash.
Calculating average backlash
Example
Average backlash = 1.20 mm . 4= 0.30 mm.
If the individual measurements differ by more than 0.06 mm this means that the ring gear is not correctly installed or that the ring gear and pinion themselves are defective. Recheck the installation, and if necessary replace ring gear and pinion.
Determining shim S2 thickness
Shim S2 installation position: opposite the ring gear
S2 = Installed shim
- average backlash
+ Lift (constant value)
Lift = 0.15 mm
Example
Different tolerances make it possible to select exact thickness of the shim(s) required.
Table of shims
Determining shim S1 thickness
(Ring gear side)
Example
Table of shims
Different tolerances make it possible to select exact thickness of the shim(s) required.
- Replace temporary S1 shim with final So shim after determining backlash.
- Install correct shim S1 on ring gear side, and shim S2 opposite of ring gear, if necessary install 2 shims.
Carrying out check measurement
- Measure backlash four times around circumference.
^ Backlash must be: 0.12 - 0.22 mm
If the individual measurements differ by more than 0.06 mm this means that the ring gear is not correctly installed or that the ring gear and pinion themselves are defective.
Recheck the installation, and if necessary replace the ring gear and pinion.