Drive Pinion, Adjusting
Drive pinion, adjusting
(Adjusting drive pinion and hollow wheel)
Special tools and equipment
^ VW 385 Universal measuring tool
^ VW 387 Universal dial gauge holder
^ VW 402 Thrust plate
^ VW 407 Thrust tool
^ VW 771 Multi-purpose tool
^ 3062 Thrust disc
^ 3114/2 Straightening tool
^ 3116 Spring pin
^ Torque gauge 0 to 600 Ncm
^ Dial gauge
^ Dial gauge extension 6.5 mm
^ Dial gauge extension 30 mm
Re-adjustment of the drive pinion according to the following instructions is only necessary if the final drive set, taper roller bearing for drive pinion and transmission housing are being replaced. Go to Adjustment overview.
Determine total shim thickness "Stotal"(S3 plus S4)
(Setting preload of taper roller bearing for drive pinion).
^ Differential is removed.
- Clamp drive pinion in vice using vice clamps -A-.
- Insert taper rollers with grease, assemble drive pinion and hollow shaft.
- Rotate hollow shaft against drive pinion 5 turns in both directions to settle taper roller bearing.
- Preload drive pinion/hollow shaft to 10 Nm, hold hollow shaft tight for this step.
- Install large taper roller bearing outer race into transmission housing without shim
- Press small taper roller bearing outer race together with a 1.00 mm thick provisional shim S4* fully into bearing plate.
Note: For measurement purposes a shim S4 with a thickness of 1.00 mm is inserted provisionally. It is referred to as S4* in the following. After determining measurement "e", S4* is replaced by the final shim S4.
- Insert completely assembled pinion shaft in transmission housing.
- Install bearing plate with dowel sleeves and tighten bolts to tightening torque.
- Rotate drive pinion and hollow shaft 8 turns in both directions prior to each measurement in order to settle taper roller bearing.
- Install measuring tools.
- Use 30 mm dial gauge extension
- 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.
- Move drive pinion upward and downward without turning; read off play on dial gauge and note. (Example: 0.90 mm)
^ Before each measuring procedure the drive pinion must be turned together with the hollow shaft in order to avoid obtaining a false reading.
The specified bearing pre-load is obtained by adding a constant pre-load value (0.15 mm) to reading obtained (0.90 mm) and thickness of shim S4* (1.0 mm).
Stotal = S4* + reading obtained + pre-load
Example:
Determining thickness of provisional shim S3*
Provisional shim S3* = S total - S4*
Example:
- Removing outer race for large taper roller bearing Inserting provisional shim S3* into transmission housing and re-installing outer race.
- Insert completely assembled pinion shaft in transmission housing again.
- Install bearing plate with dowel sleeves and tighten to 25 Nm.
- Rotate drive pinion and hollow shaft 8 turns in both directions prior to each measurement to settle taper roller bearing.
Determining measurement "e"
- Set universal mandrel VW 385/1 setting ring to dimension a 65 mm.
- Adjust moveable setting ring to measure b = 55 mm.
- Arrange universal mandrel as illustrated. Dial gauge extension VW 385/15 = 9.3 mm.
- Set master gauge VW 385/30 to RO = 59.65 mm and install onto mandrel.
- Set dial gauge (3 mm measuring range) to zero with 2 mm preload.
- Place end measuring plate VW 385/17 onto drive pinion head.
- Remove master gauge and insert measuring mandrel in the housing. Centering disc VVV385/3 faces toward cover for final drive.
- Install final drive cover and tighten 4 bolts to 25 Nm.
- Using sliding setting ring to pull 2nd centering disc VW 385/2 outward until mandrel can still just be turned by hand.
- Measure dimension "e".
Turn mandrel until the dial gauge extension touches the final measuring plate on pinion shaft head, then measure maximum deflection (return point). The measured value is dimension "e".
Example:
0.16 mm (red scale)
- Turn mandrel until the dial gauge point touches the end measuring plate on drive pinion head, then measure maximum deflection (return point).
Measurement in following example: "e" = 0.16 mm (in red scale on dial)
Determining thickness of shim S3
S3 = S3* + r + e
("e" in black scale)
S3 = S3* + r + e
("e" in red scale)
Notes:
^ 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.
^ If dial gauge reading is in red scale, subtract dimension "e".
^ If dial gauge reading is in black scale, add dimension "e".
Example:
Note: Allocate shims using spare part catalog.
Available shims for S3
Part numbers:
go to Parts catalog
- Different tolerances make it possible to obtain exact shim thickness required.
Determining thickness of shim S4
S4 = S total - S3
Example:
Note: Allocate shims using spare part catalog.
Available shims for S4
Part numbers:
go to Parts catalog
- Different tolerances make it possible to obtain exact shim thickness required.
Carry out check measurement - checking dimension "r"
- Install pinion shaft with measured shims S3 and S4 and turn several times in both directions.
Insert universal mandrel and measure dimension "r".
If the correct shims have been selected the D. T. I. must now indicate the mark dimension r (reading anti-clockwise on red scale) within a tolerance of ± 0.04 mm.
Measuring frictional torque (check)
Note: Taper roller bearings for drive pinion/hollow shaft 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,
- Install new taper roller bearings in delivery condition and do not oil additionally.
- Measuring frictional torque
With torque gauge -A-, 0 to 600 Ncm, standard commercially available
New bearings
80 to 150 Ncm
Used bearings 1)
30 to 60 Ncm
1) with at least 50 km service