Disassembly and assembly of the primary shaft (Audi 100 C3)

Disassembly

Remove the 4th gear retaining ring.

Remove the thrust washer and the fourth gear with the needle bearing.

Place the primary shaft with the 3rd gear pinion on a press and press off the 3rd gear pinion, the synchronizer sliding sleeve and the hub with the synchronizer locking rings.



Check the wear of the synchronizer locking wheels. To do this, press the locking rings against the gear synchronizer cones and use a feeler gauge to measure the axial clearance between the end of the locking ring and the end of the gear synchronizer ring gear, which should be at least 0.5 mm. If the clearance is smaller, replace the synchronizer locking rings.





Press the inner race of the rear bearing using a press.

Assembly

Connect the sliding sleeve to the synchronizer hub of the third and fourth gears, directing the beveled edge of the internal splines of the hub towards the third gear pinion, and the installation groove on the outer rim of the hub towards the fourth gear pinion (see photo).

Slide the sliding sleeve onto the synchronizer locking rings, aligning the cracker grooves on the rings and the hub. Install the crackers and springs by arranging the spring connectors at 120°. The curved ends of the springs must be inserted into the cracker recesses.

Install the 3rd gear pinion together with the needle bearing.

Press the synchronizer of III and IV gears onto the shaft.

Install the 4th gear pinion together with the needle bearing.

Measure the axial runout of the fourth gear pinion and install the appropriate thrust washer so that the clearance is within 0.10-0.40 mm.



Install the rear bearing inner race using a drift.