Jeep Brake Upgrades - Brake it DownPosted in How To: Suspension Brakes on March 26, 2015
We usually don’t even think twice about adding lift kits along with larger tires and wheels to our Jeeps, but bigger and heavier rolling stock can wreak havoc on braking performance. In most cases, it’s not an issue at slow speeds. Brake performance only seems to matter most during that split second when traffic quickly slows or stops completely. It’s when both of your feet are mashing the brake pedal and you know you’re going to end up stopping several feet into the vehicle in front of you. The brakes are more important than any other component on your Jeep. If you aren’t able to stop, you’ll never make it to your next trail day. Improving brake performance is easy and can be done in several different ways. Understanding the fundamentals of how your brakes work will help you decide what brake upgrades will work best for you.
All Jeep brakes from 1941 to the present are based on a simple hydraulic fluid system. When you depress the brake pedal, a leveraged arm pushes a piston into the master cylinder. The piston compresses the brake fluid. That pressure is delivered through the steel and flexible brake lines down to the calipers (disc brakes) or wheel cylinders (drum brakes), where pistons are forced out of their bores, pushing a friction material (brake pads or shoes) into the braking surface of a rotor or drum. This, in turn, creates heat at the friction surface, making your brakes one of the most inefficient power generators ever invented. Fortunately, we don’t use them for that. We use them to stop our Jeeps. Improving your brake system and decreasing stopping distances can be done by upgrading any or all parts of this system.
Many Jeep owners are terrified of cracking into the hydraulic brake system. The fear is not unfounded. Any air in the system will cause a spongy pedal and terrible braking issues. However, the hydraulic brake system isn’t all that complicated, and there are many aftermarket bleeder kits available that can quickly and easily help you remove the air from the system. It’s good knowledge to have, especially in wet areas. Brake fluid can be contaminated with water extremely easily, which causes the insides of the components in your brake system to corrode. It’s a good idea to completely bleed the brakes with fresh fluid once a year or so for optimum performance and brake component longevity.
One of the easiest brake upgrades that you can make is with the brake pads. Using a high-performance friction material can result in up to a 40 percent improvement in brake effectiveness. Aftermarket performance brake component companies such as EBC (ebcrotors.com) offer brake pads for many different applications. Some of the best EBC pads for Jeeps are the Yellowstuff and the new Orangestuff SUV pads. These pads are designed for street use. Full-race pads are not good for street use because they require much higher temperatures to function properly. These higher brake temperatures are rarely reached outside of a racetrack. Track-only pads will not perform as well as a stock OE pad in a typical street application.
When replacing brake pads and shoes, it’s always a good idea to have the rotors or drums turned. This provides a smooth flat surface for the friction material to make contact. Older drums and rotors can warp from heat. This warping will cause a pulsating pedal and poor brake performance. Rocks getting wedged into the pads and shoes often cause grooves worn into the rotors and drums. These grooves also hurt brake performance. If the grooves are too deep or the rotors or drums are worn out, you may need to replace them. You can only turn a rotor or drum so much. The minimum thickness (rotors) and maximum diameter (drums) is usually cast or stamped into the parts. Needless to say, it’s not a good idea to install new pads or shoes on unturned rotors or drums. Braking performance will be sacrificed in most cases; not to mention you’ll be replacing those new pads or shoes a lot sooner than you would if you had the parts turned.
Switching to a larger brake caliper will allow the use of larger pads; however, this will generally create more heat that may not vent out of the rotors quick enough to make the swap effective. To combat this, larger diameter rotors are often used in conjunction with larger pads and calipers. This increases the swept area of your brakes. The swept area is the total surface area that the friction material comes in contact with. Generally, a larger swept area equates to better braking, which will decrease your stopping distances. Unfortunately, the larger calipers and increased diameter rotors sometimes require the use of larger diameter wheels. In most cases, simply increasing the diameter of the rotors and relocating the stock calipers to fit is enough to significantly improve braking performance. The larger rotors can dissipate heat more effectively. Moving the calipers outward and away from the hub center gives the brakes a greater mechanical advantage on the spinning wheels.
Just as with larger rotors, increasing drum brake diameter and width is an easy way to increase brake performance on older Jeeps. It is extremely common to see 10 and 11-inch FSJ drum brakes on older CJ Jeeps. It’s a fairly simple bolt-on swap that you can do in your garage. Companies like Herm The Overdrive Guy (hermtheoverdriveguy.com) and Willys Jeep Parts (willysjeepparts.com) offer 11-inch front and rear drum brake swap kits for early Jeeps. The kits completely replace the troublesome 9-inch drum brake assemblies.
Because brakes work by converting motion energy to heat energy, the best brakes are those that can clamp the hardest and dissipate heat the fastest. Disc brakes clamp and dissipate heat better than drum brakes. Another downfall of drums is that they are extremely susceptible to intrusion of water or mud, which causes a significant loss of brake performance. If you live in a wet area, consider upgrading from drums to disc brakes. Mud will cause all kinds of troubles for a drum brake system. Once it gets in there, it wears out the brake shoes quickly and unevenly. Simply switching from drums to disc brakes will result in a significant improvement in brake performance. Since about 70 percent of your Jeep’s stopping power comes from the frontend, consider swapping to discs on at least the front axle of all Jeeps. Swapping to front disc brakes on your older Jeep can be done with off-the-shelf factory parts in most cases. If you want the hard part done for you, Herm The Overdrive Guy offers complete front and rear disc brake kits for early Jeeps. Jeeps with rear drum brakes can be upgraded to discs with one of the many aftermarket kits available from companies like TSM (tsmmfg.com).
Switching to disc brakes isn’t always as easy as changing the brakes at the wheel ends. Because disc brakes operate at much higher hydraulic pressures than drums, you may need to change your proportioning valve, master cylinder, and in some cases, the brake pedal assembly or brake booster. Herm The Overdrive Guy has developed several kits that allow the use of a safer, more effective dual-pot master cylinder on early CJs. The kits are available for both disc and drum brake applications. Trying to use a drum brake master cylinder and pedal assembly with disc brakes or oversizing the calipers on a disc brake system can result in a very stiff pedal that requires a strong leg to get your Jeep to stop. Some modifications can result in a spongy poor-performing brake system. When making brake upgrades, make sure you know all of the parts that you need ahead of time, or you could end up with brakes that work worse than what you started with. If you have made several brake modifications and have significantly altered your non-ABS Jeep, you should consider replacing your factory proportioning valve with an adjustable unit. This will allow you to tune-in the rear brake pressure to keep the rear brakes from locking up too soon. In some cases, you may be able to increase the rear brake pressure over stock to help decrease braking distances.
All new Jeeps have power-assist brakes. Most of them are vacuum-assisted, but it wasn’t always that way. Early Jeeps have manual brakes without a power-assist. Some Jeeps have a vacuum power-assist, but it leaves a lot to be desired. Companies such as Vanco (vancopbs.com) offer modified brake booster and hydroboost systems for many Jeep applications. These systems increase line pressure, while decreasing the leg-effort you have to put into stopping, making them the perfect addition to a Jeep with bigger tires. The power steering pump powers hydroboost systems. These are most commonly found on diesel-powered rigs because the engines do not create the vacuum required for a traditional brake booster to function. While some people insist on installing a hydroboost system on gas-engine Jeeps, it’s really not necessary unless there are clearance issues around the master cylinder that don’t allow the use of a traditional vacuum-operated brake booster.
In the past, race cars used cross-drilled rotors. This was done by drilling many small holes through the rotor braking surfaces and into the vent area. Technically, this decreases the swept area, but it improves braking performance by helping to keep the brakes cooler. It also has another positive effect. Dust and gas collect between the brake lining and the braking surface of the rotor during hard deceleration. This hurts brake performance by pushing the pads away from the rotors. The cross-drilled holes allow a place for the gasses and dust to escape. However. the problem is the heat and stress created in a braking environment often cause cracks to form between the cross-drilled holes. In a worst case scenario, the crack could lead to a catastrophic rotor failure, sending a hot chunk of iron spinning off of the vehicle, which would mean complete brake failure. So, many companies such as Brake Performance (brakeperformance.com), EBC, and SSBC (ssbrakes.com) put CNC mills to work, cutting gas slots and dimples into the braking surface instead. The machined slots and dimples allow the gases and dust to escape without degrading the strength of the rotor. The dimples and slots also help wipe away water and mud from the braking surface. Dimpled and slotted rotors are an easy bolt-on upgrade for any disc-braked Jeep.
Although, we wouldn’t recommend it on a street-driven Jeep, we have seen drilled drums on some low-buck off-road-only 4x4s. The many small holes in the drum braking surface allow water, mud, and sand to more easily escape the brake assembly. In reality, your efforts would be better spent installing disc brakes.
Something as simple as changing your wheels and tires can significantly improve braking performance. Lighter tires and wheels will generally stop faster than heavy tires and wheels. Even an open-wheel design will allow more airflow around the brakes than a closed-off wheel design. The undeniable truth is that cooler brakes stop quicker and keep you from rear-ending that moron in front of you.