Off Road Braking, Truck Brakes, and Truck Braking

To figure out your truck’s pedal ratio, divide A by B. For example, if the distance from the pivot point to the master cylinder rod (A) is 2 inches, and the distance between the pivot point and the foot pad (B) is 12 inches, then divide 12 by 2. The answer is 6, which means the pedal ratio is 6:1. This will result in 600 pounds of force being exerted on the master cylinder when 100 pounds of force is applied to the pedal.
To figure out your truck’s pedal ratio, divide A by B. For example, if the distance f
The pedal ratio on most vehicles is non-adjustable, but a few enterprising people have devised ways to modify the pedal geometry for more-effective braking. Jason Bunch of Tri-County Gear developed an adjustable pushrod for 1976-1986 Jeep CJs with power brakes. The power booster is mounted on a bracket to the firewall with a bellcrank arrangement. By drilling a few holes to relocate the bracket and the pushrod, greater mechanical advantage is gained and braking performance is increased.
The pedal ratio on most vehicles is non-adjustable, but a few enterprising people have dev

Wheel cylinder diameters on drum brakes vary from 7/8 inch to about 1-1/4 inches for regular light-duty vehicles. Many wheel cylinders are physically interchangeable, but doing so can be dangerous if you don’t understand the basics. Switching to disc brakes is another popular alternative, but buying a kit from a reputable manufacturer is usually a better bet than swapping in mismatched parts.
Wheel cylinder diameters on drum brakes vary from 7/8 inch to about 1-1/4 inches for regul
Since most of the braking is done by the front wheels, a proportioning valve is used to limit pressure to the rear brakes so they don’t lock up prematurely. This factory unit also includes a metering valve for the front discs and a warning light switch in case pressure in the front or rear is lost, so it is called a combination valve. An adjustable proportioning valve can be a handy item for dialing-in the amount of rear pressure on any custom brake setup, but it isn’t always necessary.
Since most of the braking is done by the front wheels, a proportioning valve is used to li

Any brake system must contain the proper brake fluid and be completely bled of air. Even though the new silicon brake fluids don’t absorb water like standard fluids, they do have a tendency to compress slightly and give a spongy feeling at extremely high temperatures, such as are encountered in racing. However, if you are plagued by corrosion and water contamination, silicon-based fluid is a good alternative.
Any brake system must contain the proper brake fluid and be completely bled of air. Even t
If you don’t know the diameter of your wheel cylinders, the answer is on the inside. Rather than measure the actual cylinder bore, look on the back of the cup; the diameter is usually molded into the surface of the rubber. These diameters are important should you want to calculate piston displacement or line pressures when troubleshooting or modifying a brake system. Many times, larger- or smaller-than-standard wheel cylinders can be swapped to correctly bias a system for better braking performance.
If you don’t know the diameter of your wheel cylinders, the answer is on the inside.

Early 4x4s usually came with small and inefficient brakes, as illustrated by this 9-inch-diameter drum on an early Jeep. Later 11-inch drums provide greater surface area and stopping power, especially when combined with different size wheel cylinders. If you’ve ever had to hold the brake pedal to the floor on the side of a hill to keep from rolling over, you know how important low pedal pressure and quality brakes can be.
Early 4x4s usually came with small and inefficient brakes, as illustrated by this 9-inch-d

Caliper swapping can be used to bias a brake system or adjust it for a mismatched master cylinder, but a well-thought-out system should be planned before jumping in to fix a mistake. Rear disc systems can be especially troublesome if piston diameters are either too small or too large compared with the surface area of the original wheel cylinder.
Caliper swapping can be used to bias a brake system or adjust it for a mismatched master c
Most standard GM calipers for 4x4s are the same, but some two-wheel-drive GM calipers will fit the brackets and function reasonably well, even though they have different piston sizes. This can lead to unequal braking force, especially if they’re on opposite sides of the same axle. However, proper bias of a system can be achieved by using different size calipers on the front or rear axles depending on what the system needs.
Most standard GM calipers for 4x4s are the same, but some two-wheel-drive GM calipers will

Aftermarket kits for disc brakes are usually properly matched to a specific vehicle application using the stock master cylinder. On some kits, a replacement master cylinder is available, as well as adjustable proportioning valves to set the front-to-rear brake bias correctly. Proper biasing is when the rear brakes lock up just after the front ones during a panic stop.
Aftermarket kits for disc brakes are usually properly matched to a specific vehicle applic

Brakes are rather simple when you think about it; you stop if you have them and crash if you don't. Somewhere between these two extremes lay the majority of our own brakes and, for the most part, they usually function pretty darn well.

But for those of you who swap brake parts to build custom creations or are saddled with a project that wasn't done right, this story will give you the basics on the three little-understood aspects of a hydraulic braking system that have the greatest impact on how well it works: pedal ratio, master cylinder bore size, and hydraulic line pressure.

One of the biggest braking problems occurs when a stock vehicle, after it's had 1,000 pounds of accessories added and bigger tires slapped on, just won't stop like it used to.

If you've ever noticed the drum and rotor differences between a 1/2-ton and 3/4-ton truck, it's obvious that size does make a difference. The heavier-rated truck is capable of carrying a heavier load, and the larger brakes are properly designed to safely stop that theoretical maximum weight.

Does that mean your overweight Suzuki needs 1-ton-rated brakes for the ultimate in stoppage? No, because the extra weight of the components themselves would outweigh the advantages. While the ideal situation is to figure out what you need as far as stopping power, most people are unaware of how to do it. The standard answer is to replace drum brakes with discs, but disc brakes do not necessarily stop better than drums, due to the larger frictional area of drum brakes and their self-energizing feature. However, disc systems definitely work better in the 'wheeling world, because they offer consistent operation in high-heat and wet situations and are much easier to maintain and adjust. Whether you go with discs or drums, safe, effective braking is the ultimate goal. Achieving that requires either the hit-or-miss approach of parts swapping, or a real understanding of the relationship between your foot pressing on the pedal and the tires grabbing the ground.

Probably the three most misunderstood factors that affect braking performance are pedal ratio, master cylinder pressure, and master cylinder volume. If these three items are correct, other issues such as the type of lining material and brake-biasing procedures can easily be handled. For example, if the custom brake system on a truck doesn't stop it sufficiently many owners will just throw on better brake pads, when in reality the pedal ratio or the pressure or volume to the calipers may be wrong.

In addition to explaining these braking mysteries, we have also included a few tricks and tips, along with some associated formulas for figuring out how to stop your rig in the real world, that we've learned through our own hit-or-miss upgrades.

But remember, the braking system on your vehicle is one of the most important aspects regarding the safety of yourself and others. If you cant modify the braking system correctly, dont do it at all. Its far better to leave this type of work to the experts than to end up in a ditch, or worse.