Ford Bronco Brake Upgrade - Bronco Boosting

The new hydroboost unit bolts to the firewall. The master cylinder then bolts to the end of it. You can see the inlet and outlet hydraulic fluid ports that will be plumbed. The blue anodized can is an accumulator or nitrogen-reserve bottle which stores hydraulic power-steering pressure should the engine stall. This allows you to continue to have power assist with a stalled vehicle for about three braking applications of the pedal. After this reserve depletes, the brake behaves like a normal unassisted brake system until the engine restarts, and the accumulator is refilled.

The first step in the installation is to remove the original master cylinder along with the stock hard-steel brake lines. New lines will be needed as the addition of the boost unit moves the master cylinder farther out from the firewall.

Normally you would have a high-pressure fluid line running from the power-steering pump to the steering box, and a low-pressure fluid return to the pump reservoir. With the hydroboost system, you remove the high-pressure hose from the pump and run a new one to the boost unit. Another new hose is run from the boost unit to the steering box. Finally, low-pressure returns are plumbed from the boost unit and the steering box. Here, the pressurized fluid line is plumbed from the boost unit over to the power-steering box.

High-quality Aeroquip hoses and AN steel fittings were used to build the high-pressure hoses to length. Doing it this way allows you to custom-fit the length and routing to best suit your specific application.

Here is a completed high-pressure hose. In this case, a 90-degree elbow was used at the hydroboost unit to clear the adjacent intake plenum.

Using the old master cylinder as a guide, we measured the length of the exposed pedal rod from the master-cylinder flange to the center of the rod eye.

With the rod measurement set, the rod was locked in place with a jam nut. The rod length helps set the brake-pedal height in the cab.

Normally the boost unit comes with a barbed fitting for the low-pressure return hose to the steering pump or reservoir. In this case, that fitting was removed and replaced with another threaded AN fitting, as all the hoses were upgraded to higher-quality components.

The boost unit was installed onto the firewall using three existing threaded holes. Hydratech provides all the needed hardware for the assemblies.

Here you can see the rod exiting the boost unit. With both vacuum and hydraulic boosters, the input rod from the brake pedal enters the booster and is intercepted and routed through the boost mechanism. However, in both cases, should the boost system fail, the pedal input rod will still contact the input rod at the master cylinder to operate the master correctly. This fully manual fail-safe mode allows the brakes to continue to operate unboosted should the boost system fail.

The remaining hoses were added to complete the input and output set and the low-pressure return line.

The new master cylinder was bench-bled to fill it with new fluid and purge any air bubbles inside. Some old steel brake lines were formed and used to pump the fluid from the master output ports back up to the fluid reservoir on top.

The master cylinder was bolted in place at the end of the boost unit.

We used a set of DOT-approved braided stainless steel brake lines from Crown Performance in place of the original hard-steel lines. The hydro setup generates higher line pressures, so it's a good idea to ensure your brake lines are up to the task.

The new brake lines were added to the outlets on the master cylinder. A flare-nut wrench comes in handy here to ensure the fittings are well tightened without harm to the hex portion.

Here's a view under the dash. With the boost unit bolted to the firewall, the linkage rod is connected and pinned to the brake pedal. Final pedal height adjustments can be made once the system is completely up and running.

With the new master installed, it was time for bleeding the brake system. While you're at it, why not do a good flush by running some extra fluid through the lines? When's the last time you did a brake-system fluid refresh?

We also did a quick check of the other brake components while they were visible and topped off the power-steering fluid level to accommodate the volume added with the new hoses and boost unit.

With the complete assembly installed, you can see that the master sits farther forward from the firewall. With everything bled, topped, and checked for leaks, we found the system came alive when we fired up the engine. Brake action was smooth and strong and helped haul down the 35-inch tires on this '69 Bronco.