Distance between the end face of the main gear pinion and the differential axle (Audi 100 C3)

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 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 adjusting the adjusting ring S of the required thickness to the outer ring of the rear bearing of the secondary shaft in the gearbox housing.

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 "r" 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 200 Ncm using a torque wrench.

The pinion gear, after tightening the bolts, assumes 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 (calibrated to a preload of 2 mm) to "zero" using the VW 385-30 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".

Selecting the secondary shaft rear bearing adjusting ring

If the final drive is to be used again, press the outer race of the rear bearing together with the old adjusting ring into the gearbox housing. If parts have been replaced, install the outer race of the bearing without the adjusting ring.



Install the secondary shaft and press on the second inner race of the rear bearing, as well as the 5th gear.

Attach the gearbox housing to the clutch housing using a new gasket.

Tighten the secondary shaft rear end nut to a torque of 10.0 kgf·m.

Install the special secondary shaft preload adjusting washer VW 381/11 as described in the previous paragraph.

Install the VW 385 measuring mandrel (calibrated to a preload of 2 mm) to "zero" using the VW 385-30 indicator, measure the value "g" and compare it with the calculated value "r" if the main gear was replaced, or with the value marked on the driven gear if the main gear was replaced. If the obtained value "r" is less than the calculated one, then the adjusting ring S3 of greater thickness should be installed, and vice versa. The difference between the obtained and calculated values "r" shows how much the thickness of the adjusting ring S3 should be reduced or increased.

Remove the measuring instrument kit and install the selected adjusting ring S3 under the outer ring of the secondary shaft rear bearing.

Install the secondary shaft.

Preloading differential bearings and adjusting the lateral clearance between the teeth of the main gear gears

These operations are carried out as described for the CP type 014 II, see section "Four-speed gearbox".