Adjusting track density by changing PES algorithm when servo writing a disk drive from spiral tracks

A method of writing product servo sectors to a disk of a disk drive to define a plurality of data tracks, the disk drive comprising control circuitry and a head disk assembly (HDA) comprising the disk, an actuator arm, a head coupled to a distal end of the actuator arm, and a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk, the disk comprising a plurality of spiral tracks, the method comprising the steps of:

• (a) using the head internal to the disk drive to read the spiral tracks to generate a read signal;
• (b) processing the read signal to synchronize a servo write clock;
• (c) processing the read signal to generate a position error signal (PES) according to a PES algorithm, the position error signal used to maintain the head internal to the disk drive along a first servo track;
• (d) using the head internal to the disk drive and the servo write clock to write product servo sectors along the first servo track;
• (e) adjusting the PES algorithm to seek the head to a second servo track;
• and
• (f) using the head internal to the disk drive and the servo write clock to write product servo sectors along the second servo track.