The Wilwood 120-9703-SI is a four-piston, forged billet aluminum DynaPro Lug Mount caliper. The manufacturer presents it as the newer generation of the long-running Dynalite series, and the body is stress-flow forged from premium grade billet. The four pistons are stainless steel, and the piston area is 3.00 square inches. This SI model is side-inlet and uses the Quick-E-Clip pad retention system, so you get a race-oriented caliper with a stock-style pad-changing approach.
Choose this over a stock caliper or a cheaper Dynalite-style unit for the bridge structure. The manufacturer states that center bridge bolts are included with all side inlet "SI" models, which helps resist separation under high load. Every DynaPro also carries Wilwood exclusive SRS bridge plates that reduce bridge wear from pad gouging. Fitment is universal, with a 5.25-inch mount center and compatibility with 13.06-inch rotor diameter and 0.81-inch rotor thickness. Confirm your bracket and rotor before ordering.
The manufacturer lists the DynaPro Lug Mount as a universal fit, so compatibility depends on your bracket's 5.25-inch mount pattern and a rotor measuring 13.06 inches by 0.81 inches.
Per the manufacturer, center bridge bolts come with side inlet SI models, and they are available as an upgrade on the other configurations.
Bleed the system from the top bleed screws only, and make sure the bottom screws are tight, as the manufacturer's DynaPro instructions describe. Wrap PTFE tape on the 1/8-27 NPT inlet threads. Owners on user forums say the bridge bolts can make pad changes fiddly, since you must line them up with the far-side threads, and they note that caliper centering over the rotor affects judder. Bed in the pads afterward using the manufacturer's procedure. Because this is safety-critical brake work, a person with brake experience should perform the install.
