The Wilwood 160-8399 is a left-hand (L/H) GT 72 curved-vane slotted brake rotor, with a 14.00 inch diameter and 1.25 inch width. It is cast from Wilwood's Spec-37 iron, a proprietary alloy the manufacturer developed to hold up under extreme heat. Its curved vanes and GT asymmetrical slot pattern are built to move air through the rotor and to shed heat and debris. That matters on a track car that goes from fast laps to hard stops and back again, where a cheaper rotor can distort or crack. Buyers choosing between this and lower-cost slotted rotors are paying for the heat-tolerant alloy and the tight machining tolerances. Every Spec 37 rotor is precision machined to less than .001 run-out, flatness, and parallelism.
Before ordering, confirm the hub fit. The manufacturer's data lists a 12-on-8.75 inch bolt circle, a 8.25 inch lug ID (registration diameter), and a 10.00 inch far-side inside diameter, so check these against your hub and hat. Owners on user forums typically pair a 14-inch rotor like this with a big-brake caliper, so verify caliper bracket and wheel clearance before buying. Search terms that match this part include "Wilwood GT 72 curved vane 14 inch L/H rotor," "Spec-37 iron slotted brake rotor," "12 on 8.75 14x1.25 rotor," and "left hand directional vane track brake rotor."
