Husqvarna TC 450 Workshop Manual page 225

FRONT SUSPENSION
Assemble the dust seal on the outer tube.
Make sure there is no play between the dust seal and the outer tube.
Reassembly of the cartridge unit.
Tighten the nut until it stops on the inner push rod.
Make sure that the length of the thread of the inner push rod is at least 15mm
(0.6in.).
Fill the cartridge with the specific oil.
Eliminate any air inside the cylinder by moving the piston rod up and down, slowly.
I.33
Part. N. 8000 H1344 (10-2009)