Table of contents: Principle of regulation ↓ Determining the value of the… ↓
Principle of regulation
The distance between the differential axis and the end of the drive gear determines the location of the contact patch in the engagement of the main gear gears. When installing the secondary shaft in the gearbox, this distance affects the degree of wear and noise of the main gear gears. Therefore, it must be adjusted with particular care using a special tool.
The initial value for adjustment is the calculated value of the distance between the differential axis and the end face of the drive gear (dimension "Ro", see diagram), adjusted by the correction "r", determined during the manufacture of the drive gear. The adjustment consists of placing the adjusting ring S3 of the required thickness under the outer ring of the secondary shaft rear bearing to shift the drive gear in the gearbox housing.
Diagram of installation of measuring instruments for calculating the distance between the end of the drive gear and the differential axis: 1 - measuring mandrel VW 385/1; 2 - measuring mandrel VW 385/2; 3 - indicator rod VW 385/13; 4 - VW 385/16 indicator extension; 5 - support mandrel of the indicator leg VW 385/33
Determining the value of the correction "r"
Note. This measurement is taken if the driven gear of the main transmission does not have the correction marking "g" in hundredths of a millimeter from the nominal position of the driving gear, and also if there has been a replacement of parts that directly affect the position of the driving gear of the main transmission: the rear double-row tapered roller bearing of the secondary shaft, the crankcase or rear cover of the gearbox, the bearing of the 1st gear gear.
Remove the rear gearbox cover.
Install a special adjusting washer VW 381/11 and secure it strictly at a right angle relative to the secondary shaft, tightening two M8x50 bolts by hand.
Tighten the bolts to 20 Nm using a torque wrench.
The pinion gear, after tightening the bolts, takes the position it occupied when the rear cover of the gearbox was installed. This operation must be carried out very carefully every time the distance between the end of the pinion gear and the differential axle is adjusted.
Remove the differential.
Install the VW 385 measuring mandrel into the clutch housing (calibrated to a preload of 2 mm) to "zero" using the VW 385-3G indicator.
Determine the calculated value of the dimension "r", which is the deviation from the dimension "Ro".
When replacing parts, select the thickness of the adjusting ring to achieve the maximum possible accuracy in maintaining the obtained dimension "r".
Adjustment and measurement of the distance between the end of the drive gear and the differential axis and the lateral clearance in the engagement of the main transmission gears: 1 - secondary shaft rear tapered roller bearing; 2 - differential bearing; 3 - clutch housing; Ro - calculated distance between the end of the drive gear and the differential axis; g - correction to the calculated distance between the end of the drive gear and the differential axis (applied to driven gears supplied as spare parts); S1, S2 - differential bearing preload adjusting rings; S3 - adjusting ring for the distance between the end of the drive gear and the differential axis