Under-Dash Brake Pedal Assembly, Dual Diaphragm

• Universal pedal assembly allows conversion from under floor mount master cylinder to firewall mount
• Power brake pedal assembly can be used to add power brakes to early cars
• Cut-to-fit brake pedal and booster mount fits any configuration of firewall and dash
• Pedal can be mounted in five different mounting holes to change relationship between pedal and firewall
• Pedal ratio is 6:1 for ease of braking and works with all disc/drum setups
• Corvette style cast iron master cylinder provides line access from either side of unit and includes port plugs
• Master cylinder utilizes 1-inch bore with dual reservoirs for additional brake system safety
• Dual diaphragm power brake boosters are compact and works with any engine providing at least 17 in/hg of vacuum
• Kit provides easy access to master cylinder for service/maintenance versus original under floor design

Power Brakes for Your Early Hot Rod

There is no denying that early braking systems on the cars we love to build, like Model Ts, Model As, and other pre-war rides, were rudimentary to say the least, and that is putting it lightly. These early mechanical brake systems may have been OK for the speeds of the time, but drop a hopped-up Flattie in it, or even more power via a small-block Chevy, and you are really asking for trouble when you must hit the “whoa” pedal after using too much of the “go” pedal.

Updating these classics to “juice” brakes (hydraulically actuated) has been the thing to do for decades and we are here to make that conversion easier for you. From disc and drum conversions, brake lines, proportioning valves, fittings, and more, Speedway Motors has everything you need to convert to hydraulic brakes on your pre-war hot rod, including this universal firewall mount brake booster and master cylinder combo. These are the basis for your new hydraulically actuated braking system in your pre-war car and can easily be used to convert under floor master cylinder/pedal assemblies in ’40s and ’50s cars and trucks as well.

A Power Brake Conversion That Fits Most Any Engine Bay

Adding power brakes to a pre-war hot rod is not always easy. Most of these original brake systems featured a mechanical brake system and early hydraulic conversions fitted the brake master cylinder under the floor, which did not always provide the correct leverage for optimal braking. Upgrading to power brakes using our universal brake booster and master cylinder with under-dash pedal assembly is a much better solution. The manual to power brake conversion places the brake master cylinder and vacuum power brake booster on the firewall, where it is easier to service and places the master cylinder higher than the brake calipers or wheel cylinders, negating the need for residual pressure valves in most cases. The under-dash kit also provides a more modern down hanging pedal assembly, which frees up floor space in cramped hot rod cabins to allow more foot room for those longer drives. This kit works great in conjunction with a front disc brake upgrade as well.

Our under-dash power brake booster and master cylinder combo kit features a zinc-plated 7-inch dual diaphragm power brake booster that provides more assist than the standard single diaphragm brake booster and yet is only 5-1/4-inch thick, allowing the brake booster and master cylinder combo to fit in smaller engine bays with ease. The power brake system works with engine vacuum of at least 17 in/hg or can be paired with an electric vacuum pump for those with aggressive cam profiles that produce insufficient vacuum. The power brake booster assembly includes mounting hardware for the booster and the master cylinder that mounts to it. Additionally, the booster includes an adjustable master cylinder pushrod and threaded pedal rod with lock nut for pedal height adjustment. The included brake booster check valve uses standard 3/8-inch brake booster vacuum hose for your engine’s vacuum source (carburetor base plate/spacer or intake runner vacuum tree).

The included Corvette-style brake master cylinder features a 1-inch bore with front and rear divided fluid circuits for the modern safety of a split braking system. Our master cylinder is designed for disc/drum applications with ports on both sides so that you can route your brake lines inboard or outboard however you wish for function and aesthetics. This brake master cylinder is ideal for a front disc brake upgrade solution. The ports are 1/2-20 inverted flare for the front circuit and 9/16-18 inverted flare for the rear circuit. Inverted flare plugs are included to block off the opposite side unused ports. For those crafting their own 3/16-inch brake lines we offer a master cylinder fitting kit to allow direct connection. If you choose to utilize pre-made lengths of 3/16 brake line our inverted flare adapters in 1/2-inch and 9/16-inch sizes will allow direct connection to our master cylinder without having to cut and flare brake lines.

Universal Cut-to-Fit Mounting Solution

We created our under-dash pedal assembly to be a cut-to-fit solution with an adjustable pedal spacing. The bracket is made from mild steel and painted black, so it is easy to cut/trim or weld on and is a generous 14-inches long. This allows it to fit within large dash structures but can be easily shortened for more compact installations. The pre-formed pedal mounting locations provide for a 7-, 8.5-, 10-, 11.5-, or 13-inch spacing from the firewall. This allows you to mount the pedal at a comfortable working height in correlation with your throttle pedal with final adjustment handled by the threaded brake pedal pushrod of the brake booster. The brake pedal itself, no matter the mounting hole chosen, is a 6:1 pedal ratio and includes a 3-3/8-inch diameter classically styled round rubber brake pedal pad. Our kit makes a manual to power brake conversion easy, no matter the vehicle.

Booster Tech Tip (GIF)