HiSpec Rotor measurements

Diameter and Radius

The diameter, or disc size is the measurement across the face of the disc.

The radius is the measurement from the centre of the disc to the outside.




Overall thickness

This is the distance between the front and back faces of the rotor.




Flange inner diameter

This is the size of the hole through the middle of the disc, on the rear side.




Centre Bore

This is the size of the hole through the middle of the entire disc.




Pad swept area

This is the depth of the disc face which can touch the pad.




Flange thickness

This can be measured by the depth of the bell mounting holes.




PCD

This is the distance between opposite holes where the rotor bolts to the bell.




Step

This measurement is how deep the bolt face of the rotor sits, compared to the front face of the disc.

If the bolt face sits higher, it is a positive step. If the bolt face sits recessed, it is a negative step.

Negative step Positive step