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Jeep JK Stopping Power Upgrade

Posted in How To: Suspension Brakes on January 3, 2017
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Stopping is important. I'm not talking about stopping to smell the roses, though that's important too. I'm talking about stopping your Jeep on the highway or trail. Most of the excitement of Jeeping is all about going—going to new places, going over that rock, or over that sand hill. To do those things safely, though, a Jeep’s brake system needs operate effectively too. Upgrades make Jeeps heavier and their braking less efficient—good thing there is an upgrade for that too.

TeraFlex has been around the Jeep world for many years. It designs and manufactures suspension kits and all sorts of Jeep accessories. The TeraFlex Big Brake upgrade kit is what we’re talking about here, and it’s a relatively easy bolt-on kit that requires zero cutting or welding. There are multiple options for front brakes from TeraFlex. Its Performance Big Rotor kits come with and without slotted brakes and relocate the factory caliper farther away from the center of the hub. The company’s full-blown Big Brake kit includes new calipers, brackets, and larger rotors. The kit’s 13.3-inch front rotors seem to dwarf the 11.9-inch factory rotors. The calipers in the Big Brake kit are built to TeraFlex specifications, and each caliper uses dual 56mm pistons for a more evenly distributed clamping force, using composite-resin semi-metallic pads. The calipers are so big that a 17-inch or larger wheel is required.

Always layout your parts before you start any project. This gives you a chance to make sure you aren’t missing anything. Additionally, make sure to read the instructions.

Out back, the TeraFlex Big Rotor kit moves the existing caliper farther away from the center of the hub—a move that improves braking effectiveness. The kit also includes a 13 1/2-inch rotor and new caliper brackets. Slotted rotors are also available for the rear kits. These also require a minimum wheel size of 17 inches.

In addition to the rotor and caliper kits, TeraFlex offers a brake master cylinder with an oversized bore. The higher flow is required for ’07-’11 JKs and pushes 14 percent more pressure to the much bigger front calipers. If you are using the Big Rotor kits and keeping all your factory calipers, this is not needed. On our subject Jeep, an ’08 JK Wrangler, we are installing the bigger calipers, therefore the new master cylinder is required.

We performed multiple 60-0 mph brake tests before and after the approximately four-hour installation. Keep in mind that each Jeep is a little different. Tire sizes, vehicle weight, and driver are all significant variables. The JK Unlimited we used had 35-inch Goodyear MT/R tires, a hardtop, front and rear bumpers, side bars, and is loaded with gear almost all the time. The average distance taken from three stops after the new brake system was installed and the pads were “bedded” was 34.8 feet shorter (roughly 26 percent) than the stops prior to installation.

If your JK is a ’07-’11, begin the installation/swap with the master cylinder. This will help with the bleeding process later on. To avoid making a mess, we used a vacuum bleeder to suction out as much of the old brake fluid as possible. Later, we used this bleeder to bleed the system through all four calipers.
The fluid level sensor was disconnected, and then the master cylinder was unbolted from the brake booster but not removed. With the master still on the studs of the booster, we disconnected the hard lines. Using a line wrench will help to avoid damaging the nut. We then pulled the master away from the booster, making sure the O-ring didn’t get lost in the booster.
The new master cylinder was then installed on the studs of the booster. We hand-threaded the flare nuts into the master and made sure they were not over-tightened. The nuts that hold the master to the booster were then installed. We tightened them per the specs in the TeraFlex instructions.
A rag or two were stuffed under the master cylinder before we filled the reservoir completely with DOT 3 brake fluid. We then loosened the flare nuts so they both started dripping, and when the fluid level reached the max-level mark, the flare nuts were tightened.
We then loosened the flare nuts so they both started dripping, and when the fluid level reached the max-level mark, the flare nuts were tightened. The fluid level sensor plug was reconnected and the master cylinder cap replaced. TeraFlex recommends checking the pedal feel by pumping it a few times with the engine off, then again with the engine on to ensure the booster is working properly.
The front brakes on JKs are better than previous model Wranglers but can still come up short once the rig has been loaded down with a suspension lift, bigger tires, and the additional weight of dozens of other upgrades.
The caliper brackets were unbolted form the knuckles. The TeraFlex instructions listed all the wrench sizes needed. However, during this install there were several discrepancies—the JK has been in production for many years, there were bound to be changes along the way from the factory.
A wire or a zip tie should be used to hang the caliper and bracket out of the way once removed.
The factory rotor is 11.9 inches and seems small compared to the 13.3-inch TeraFlex rotor. TeraFlex rotors are dual-drilled, and the company’s rotors to accept the factory 5-on-5-inch bolt pattern, as well as the popular aftermarket 5-on-5.5-inch pattern.
Outside thickness measurements between the two rotors are the same. The major different can be seen in the width of the pad wear surfaces.
The TeraFlex instructions have good diagrams to help install the rotors with the slots facing the correct direction. We found a popular install video on the web that shows them being installed incorrectly. So please, do yourself a favor and follow the TeraFlex instructions—the slots should slant forward.
A drop of thread-lock compound was used on the bolts, and then calipers and brackets were bolted to the vehicle with the bleeder to the top. Next, we unbolted the calipers from the brackets. This requires a double wrench setup. TeraFlex added a small ledge machined into the brackets to aid in starting the separation.
Next, we installed the new semi-metallic pads. The adhesive backing from the pads was removed once they were in place.
We reinstalled the calipers to the bracket. We used a dab of locking compound on the bolts. After that, the existing brake lines from the old calipers were removed and installed on the new calipers using the new copper washers provided in the kit.
The new brakes filled up a 17-inch wheel, but there was sufficient clearance all the way around with this standard aftermarket wheel.
In the rear of the vehicle, we disconnected the calipers from the brackets using a double wrench set up. The calipers were hung out of the way, but we took care to not let them hang by the brake lines. We then unbolted the caliper brackets from the brake backing plates.
The TeraFlex rear rotors are designed to work with the OE parking brake system and are 13 1/2 inches compared to the stock 12 1/4 inches.
We suggest you thoroughly check all your brake pad hardware. After a good cleansing with brake cleaner, half of the factory pieces were found to have a small tab broken off. Hardware isn’t expensive; replace them if they are broken, worn or questionable.
The slide pins from the original brackets were reused with the new system. We cleaned the pins well and added new lube to get them sliding freely.
We installed the new rotors and caliper brackets. Locking thread compound was used on all of the caliper bracket bolts.
The new brake pads were installed in the original calipers. We also used locking compound on the caliper bolts.
We bled the entire brake system, starting with the passenger rear caliper, and worked our way around to the driver front. Even though the rear system was not directly disconnected, an air bubble may occur in the system and cause issues, so it’s just smart and easy to bleed the entire brake system after a brake upgrade such as this.
An average 60-0 mph stopping distance of 34.8 feet shorter than that we measured prior to the TeraFlex Big Brake kit installation was a substantial amount. That’s roughly a 26 percent improvement over the factory brakes on this loaded-up Jeep JK.

Amazon Affiliate links are our attempt to show you real-world pricing and availability for the products we review and install, and while the Amazon links are separate from editorial and advertising, the Four Wheeler Network may receive a commission on purchases made through our posts.



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