Hydropower For Vintage Brakes
The Ford Bronco made its debut as a '66 model in late summer of 1965 and was designed to provide reliable 4WD travel against the likes of the Jeep CJ-5 and the International Scout.
Those earliest Bronco brakes were a simple setup with 11x2-inch front drums and 10x2.5-inch rear drums on the light-duty axle and 11x1.75-inch drums on the heavier-duty (large bearing) rear axle. Both rear axles were the venerable Ford 9-inch, and the early models used a Dana 30 front axle.
Brake advancements were slow on the Bronco. In 1967, Ford swapped to a dual master-cylinder setup in a split hydraulic system and added a self-adjustment feature to the drum brakes. Finally in 1976, the Bronco got a vacuum-assist power-brake option with front disc brakes and upgraded 11x2.25-inch rear drums.
Although these latest-model brakes work fairly well for stock vehicles or those with mild mods, the addition of bigger, heavier tires can tax the system and lengthen stopping distances. Big tires, tall lifts, and marginal brakes can all add up to scary stopping and loss of control. But there are other improvements available.
A conventional vacuum booster works by using the energy of the engine-intake vacuum (or a vacuum pump) to help reduce the braking effort your foot must apply. The booster consists of a large sheetmetal canister that is mounted to the firewall between the brake-pedal rod and the brake master cylinder. The force of the input rod is exerted on a bladder that essentially has ambient pressure on the input side but is under a vacuum on the backside. This differential pressure is used to assist the action of the brake rods.
To upgrade further, consider a conversion to a hydraulic system. Hydraulic-assist braking is often referred to as a hydroboost system and is a more powerful alternative to vacuum-boost brake assist. Hydraulic assist uses pressurized fluid from the power-steering system to help provide mechanical advantage to the master cylinder.
Many late-model fullsize heavy-duty trucks come factory equipped with hydraulic assist, making braking of these heavy vehicles with large tires fairly effortless. One big advantage of hydraulic assist over an engine vacuum-assist setup is that its operation does not vary significantly with changes in engine speed or vacuum. In fact, a system such as this works quite well with racier cams that tend to drastically reduce available intake vacuum needed for standard power brakes.
Of course, the addition of the more powerful hydraulic assist won't provide the best benefit if your power-steering pump or other brake components are in poor shape. Hydratech is an aftermarket supplier of hydroboost systems and has retrofit kits for a wide range of vehicles. Here, we'll show you the early Bronco conversion used to go hydro.