Secondary shaft axial displacement measurement scheme for determining the total thickness "Sob" of bearing adjustment rings
Press the outer races without adjusting rings of the tapered roller bearings into the sockets of the crankcase and the rear cover of the gearbox.
Install the fully assembled secondary shaft into the gearbox housing, attach the rear housing cover and tighten its mounting bolts to a torque of 2.5 kgf·m.
Attach the VW 387 stand with the indicator with an extension of about 30 mm as shown in the diagram.
Place the indicator leg on the support mandrel with a preload of 1 mm, and fix the indicator in this position, setting its arrow to zero.
Raise and lower the secondary shaft several times and determine the amount of axial movement on the indicator scale, which is, for example, 1.30 mm.
Warning: Do not rotate the secondary shaft when measuring the clearance, as this will cause the bearings to self-align and the indicator will give incorrect readings.
Calculate the total thickness "Sob" of the bearing adjustment rings using the formula:
So6 = measured clearance + bearing preload.
The value of the secondary shaft bearing preload is constant and equal to 0.30 mm. Thus
So6 = 1.30 + 0.30 = 1.60 mm.
Lubricate the bearings with gearbox oil and measure the torque resistance with a special dynamometer. It should be within 200-400 N·cm for new bearings; for worn bearings 30-60 N·cm.