Talking about safety can be boring. That is, until you really need it. Safety is not glamorous, it’s not about building more power or speed, and it rarely makes great headlines. However, safety is a vital aspect of four-wheeling. If you’ve ever been in a big hurry to stop on the road or trail, or hanging by the friction between your tires and the rock you’re on top of, all of a sudden your brakes become the most interesting thing in the world. So, looking for ways to improve braking performance is always on our minds.
We recently came across the Superlite 4R Big Brake Front Brake Kit from Wilwood Engineering (PN 140-12576) designed for 1990-to-2006 Jeep Wranglers. This upgrade/swap kit can go a long way in improving braking performance. As a matter of fact, it raises the bar with highlights such as Wilwood’s 12.19-inch vented rotor and forged Superlite 4R 12.19-inch-diameter vented rotor. The kit is complete with brake pads, superbly detailed instructions, and all the necessary hardware. Replacement brake hose should be ordered specifically for your Jeep’s lift height and other suspension modifications, so check with the Wilwood customer service crew for the best choices for your application.
Wilwood’s Superlite 4R Big Brake Front Brake Kit for the 1990 to 2006 Jeep Wrangler requires a conversion to the 1987-1989 YJ knuckle, but it delivers a 12.19-inch-diameter vented rotor and four-piston forged caliper for improved braking performance. It was easy to install, and the big rotor and custom colored caliper look great behind open-style wheels.
The only pieces the kit does not come with are the 1987-1989 Jeep YJ knuckles (also referred to spindles in some literature) that must be used to replace the 1990-to-2006 Wrangler knuckles in order to use this Wilwood front disc brake upgrade kit. Surprisingly, the YJ knuckles for this Jeep TJ swap were found easily on eBay for less than $100. They just needed a good cleaning and a coat of black spray paint to look fresh from the factory. This Wilwood brake upgrade will also require a 16-inch (or larger) wheel, and in some cases a 16 may have clearance issues depending on style and construction. You can find a “Wheel Clearance Diagram” on the Wilwood Engineering website that provides all the product dimensions; it recommends maintaining a minimum 0.080-inch clearance between the wheel and caliper in all areas.
This particular Jeep TJ has a 3.25-inch lift with green coils (as well as a number of other green accents), so the owner ordered up green calipers; however, a full spectrum of caliper colors are available when ordering the Wilwood Superlite 4R Big Brake Front Brake Kit. We’ve hit the highlights here so you know exactly what to expect.
To begin the process of upgrading this Jeep Wrangler TJ with the Wilwood Superlite 4R Big Brake Front Brake Kit with hat and 12.19-inch vented rotor, the factory knuckles (passenger side seen) must be removed and replaced with ’87-to-’89 Jeep YJ knuckles. These are not as hard as you may think to find. Ours were acquired through eBay and were less than $100 for the pair.
The factory knuckle from our 2003 Wrangler TJ (right) has integral caliper sliders that would have to be cut off to fit the Wilwood bracket and complete brake kit, but doing so doesn’t really solve the problem because then there is not enough material left on the knuckle to support the caliper bracket. However, the two beefy bosses on the ’87-to-’89 factory Jeep YJ knuckle (left) can easily accept and support the Wilwood caliper mount and caliper.
We bolted up the replacement knuckle to proper torque specs and made sure the knuckle freely turned. The upper and lower front ball joints had been replaced with new units just prior to this brake upgrade, and the new knuckle fit up perfectly.
Although all parts removed from the front axle, including shafts, hubs, and dust shields, will be reused with the new knuckles, the dust shields must be modified so they don’t interfere with the new Wilwood calipers. Kit instructions are precise and detailed with measurements and methods for cutting the shields down to size. It’s best to do this off the vehicle, and we followed that good advice.
With the axleshaft cleaned, greased, and reinserted into the axletube, the newly cut-down dust shield was replaced. In its modified form it must be reused to act as a spacer between the new knuckle and the hub, and even in its cut-down form it continues to provide some protection from dirt.
A fresh coating of grease was applied to the shaft and hub splines, and then the factory hub was reinstalled. Factory Jeep TJ torque specs were adhered to on the three bolts that secure the hub to the spindle, from behind as well as the gland nut on the tip of the axleshaft, then the grease cap and cotter pin were set.
Our next step was to install the Wilwood caliper bracket. It’s placed between the knuckle’s caliper-bracket bosses and the axle hub, and then bolted into place from the inner side. Two 0.033-inch shims are used on each bolt between bracket and knuckle, and the two bolts are temporarily tightened. More or fewer shims may be added/removed later for final adjustment of the caliper position side to side on the disc.
Once installed, the new caliper bracket provides a substantial platform for the Wilwood Superlite 4R 12.19-inch brake caliper to mount up to.
Now it was time to assemble the new disc and hat. The Wilwood Superlite 4R 12.19-inch vented disc is oriented to the brake hat as seen, with disc flanges down and brake hat flange up.
The Wilwood vented disc and the brake hat were attached to each other using the kit-supplied bolts in an alternating sequence, with a drop of red Loctite 271 on the treads of each bolt. The bolts were tightened to 25 lb-ft.
Before the new Wilwood rotor and hat can be installed, the rotor registration adapter must be slid onto the register on the axle hub. Make sure the smaller outer diameter end of the rotor registration ring is pointing outward (toward hat) when put in place.
Then, the newly assembled Wilwood rotor and brake hat were placed on the axle hub, and the hat’s holes slid over the hub’s wheel studs. Three of the five lug nuts were tightened enough to secure the rotor and hat assembly to the hub firmly for initial caliper installation. Be sure the rotor hat flange sits flush against the axle hub flange or excessive rotor runout can result.
The caliper-mounting studs were lubricated with lightweight oil, and then two 0.035-inch shims per bolt were placed on the studs. The caliper mounts to these studs, and the shims are used to adjust the caliper position height from the disc.
We then slid the Wilwood caliper over the disc and onto the caliper-mounting studs. The kit-supplied hardware was used to tighten the caliper firmly to its mounting studs so we could check alignment between the caliper and disc.
With the caliper temporarily in place, we checked the rotor and caliper alignment. The photo on left shows how our caliper looked like prior to adjustment; it’s not anywhere near centered on the rotor. The photo on right shows the caliper (with brake pads temporarily installed to check fitment) better centered on the caliper, after we removed a shim (between the caliper bracket and the knuckle) from each of the two bracket bolts before replacing the caliper. We also checked rotor depth to make sure the pads and rotors were properly aligned. Wilwood suggests leaving a 0.032-inch thickness of the radial mount pad exposed above the outer edge of the rotor. It helps avoid rotor edge grooving, and the rotors will expand when heated up to meet the radial height of the pads.
Now that the position of the caliper had been adjusted and it was properly centered and at the proper height on the rotor, the caliper was removed so the bracket bolts could be taken out one at a time and reinstalled with a drop of red Loctite 271 on their threads. The bracket bolts were then tightened to 47 lb-ft.
All lined up the way it’s supposed to be, and with all the appropriate shims in place, the caliper was remounted on the bracket’s caliper studs. Once the brake pads were reinserted, we locked it down with 30 lb-ft of torque on the caliper locknuts.
Next, we secured the brake pads by installing the center bridge pad retainer tube. It spans the opening in the top of the caliper with a bolt running through it and the locknut.
The Wilwood caliper inlet fitting was a 1/8-27 NPT; we chose a 90 to better keep the brake lines closer to the back of the wheel and make it easier to route up high and out of harm’s way. High-quality stainless steel brake hose is available through Wilwood, and it’s best to contact them with the details of your specific vehicle to select the right length and fitment.
All the parts, including a replacement frame mount, needed to hook up the new stainless braided brake hose to the OE brake lines are included in Wilwood kit. We finished in a matter of minutes and then tapped in the locking tabs to secure the connection to the frame mount. We found the 18-inch brake hose to be just right for this vehicle, as it had a mild 3.25-inch lift.
It’s all buttoned up, bled, and ready for the wheel and tire to go back on. The Wilwood Superlite 4R 12.19-inch Big Brake Front Brake Kit was easy to install. We showed you the passenger side, which took about two hours, and even though the driver-side knuckle is different, the brake kit installation is identical.