The Wilwood SRP48 SPC-37-LH-BLK-Drill is a left-hand, drilled-and-slotted vented rotor from Wilwood's SRP Drilled Performance line, with a 13.06 in diameter and 1.25 in width. The manufacturer lists it as Spec-37 Iron with 48 CV vane count and a black electro-coat finish. Its 12 x 8.75 in bolt circle is the reason to shop this part for a heavy-duty Wilwood brake upgrade.
The directional cross-drill and face-slot pattern is the main reason to pay for this rotor over a plain stock disc. Wilwood states that the venting and cleaning action of the holes and slots helps limit pad glaze, and that the grooves inhibit irregular pad compound build-up on the rotor faces. The removed material also contributes to lower rotating and unsprung suspension weight. Owners researching 12.30 lb SRP48 left-hand replacements or a 12 on 8.75 drilled rotor upgrade will want to confirm fitment against their caliper and hub before ordering.
Wilwood's manufacturer data lists this rotor as not bedded, so it should be bedded before aggressive use, following Wilwood's steps of a series of light decelerations to gradually build some heat in the brakes. Wilwood also offers factory dyno-bedded pads and rotors. Search terms: Wilwood SRP48 LH drilled rotor, 160-7799-BK, Spec-37 iron 48 vane, 13.06 x 1.25 12 on 8.75 rotor.
No. The manufacturer lists this rotor as not bedded. Wilwood sells factory dyno-bedded pads and rotors as a separate option, and its published bedding procedure is intended for a race track or other safe location.
Owners on user forums report that Wilwood calipers often need to be held vertical when bled, and that removing one bolt may not be enough to achieve that on large rotors.
This is a hat-mounted, two-piece rotor, so installation means removing the wheel, caliper, and pads, then mounting the rotor to its hat. Per Wilwood's hub-mount install sheets for other rotor kits, the hub face should be free of nicks and burrs, and the hat must seat flush against the hub or excessive runout can result. Wilwood's sheets for similar hat assemblies call for red threadlock on the rotor bolts, with optional safety wire, and owners on user forums report bolts backing out when threadlock is not rated for hot brake temperatures. Confirm torque values with the manufacturer, since the sheets vary by application. Wilwood's install sheets also note that the wheel track can change with aftermarket brakes and that at least 0.080 in of clearance should remain between the wheel and caliper. Wilwood recommends that installation be done by people experienced with disc brake systems, and brakes should be tested after installation and bled with a catch bottle.
