Determining total shim thickness "Stotal" for shims "S1" plus "S2"

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(adjustment of pre-load of taper roller bearings for differential)

Pinion shaft removed

Remove flange shaft oil seals
Remove tapered roller bearing outer races for differential and take out shims → Differential, disassembling and assembling .

Fig 1: Driving Outer Race For Tapered Roller Bearing With Shim Into Transmission Housing

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Drive outer race for tapered roller bearing (right-side) with shim "S₂ " into transmission housing. For measurement purposes use a 1.30 mm thick "S₂ *" shim (or 2 shims of 0.65 mm).

NOTE:

For measurement purposes a 1.30mm thick shim "S₂ " is inserted provisionally. This is referred to in the following as "S₂ *". "S₂ *" is exchanged with the final shim "S₂ " after determining backlash.

Fig 2: Pressing Tapered Roller Bearing Outer Race (Left-Side) Into Cover For Final Drive

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Press tapered roller bearing outer race (left-side) without shim "S₁ " into cover for final drive.
Install differential in transmission housing. The ring gear is positioned on the left-hand side (same side as cover for final drive).
Install cover for final drive with 4 bolts (20 Nm).
Turn transmission so that cover for final drive points upward.

Turn differential 5 turns in both directions so that the tapered roller bearings settle.
Place measuring plate VW385/17 on differential.

Fig 3: Installing Magnetic Plate 50Mm Dia. VW 385/17 And Dial Gauge

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Set up measuring tool using 30 mm extension.
Set dial gauge (3 mm measuring range) - A - to "0" with 2mm preload.

NOTE:

Tip of dial gauge must be located at center of differential.

Raise differential without turning, read clearance off dial gauge and write down.

Measurement in following example: 0.62 mm

Fig 4: Special Tools VW521/4 And VW521/12 Secured On Right Of Differential

Courtesy of VOLKSWAGEN UNITED STATES, INC.

NOTE:

Secure special tools VW521/4 and VW521/12 on right of differential (transmission side) to lift differential.
If the measurement has to be repeated, the differential must again first be turned 5 turns in each direction to settle the tapered roller bearings.

Formula: "S_total " = "S₂ *" + measured value + bearing preload

Example:
	Inserted shim(s) "S₂ *"	1.30 mm
+	Measured value	0.62 mm
+	Bearing preload (constant value)	0.25 mm
=	Total shim thickness "S_total " for "S₁ " plus "S₂ "	2.17 mm

Determining thickness of shim "S₁ *"

NOTE:

Provisional shim "S₁ *" is replaced with final shim "S₁ " after determining backlash.
Total shim thickness "S_total " remains unchanged.

Formula: "S₁ *" = "S_total " - "S₂ *"

Example:
	Total shim thickness "S_total " for "S₁ " plus "S₂ "	2.17 mm
-	Inserted shim(s) "S₂ *"	1.30 mm
=	Thickness of shim "S₁ *"	0.87 mm