Products to Compare (max of 3)
X
Compare These Parts
America's Oldest Speed Shop ® Talk to the Experts. Call 800.979.0122, 7am-10pm, everyday.
Help Center
Help Center

U.S.Order Line:

800.979.0122

(CST) 7am - 10pm

Race and Rod Tech Support

Mon-Fri 8am - 5pm

Canadian Order Line:

855.313.9180

International Order Line:

1.402.323.3200
Since 1952
Menu
Shop By
Support
Account

Braking Components - Selection and Design

By Jason
11 months 15 days ago
Tags: Tech, Brake

Customers often ask: "Which outlet on the master cylinder should go to the front brakes and which should go to the rear?"

Master cylinder designs vary from one model or manufacturer to another, and many have the front outlet going to the rear brakes and the rear to the front, while others have the opposite arrangement. Many dual outlet master cylinders will have a built in proportion to them. It is imperative that the installer knows what master cylinder he has and how it was intended to be plumbed.

What booster size should I use?

Power brake boosters require a minimum of 17 inches (or more) of manifold vacuum to function properly. Smaller boosters will typically require more vacuum to perform adequately. A smaller booster is a great option to consider when you’re mounting in a tight location like under the floor on the frame, or on the firewall. For full pedal assist manufacture requirements vary between 18-22”of vacuum.

When using a more radical lift cam with lower manifold vacuum supply, one option is to use a 12 volt vacuum pump available from Speedway under part number 91028146. We also offer our power brake vacuum reserve canister, part number 5503701. This will add braking performance on vehicles with marginal manifold vacuum at idle. The canister simply catches high vacuum conditions and stores it for use when the brakes are applied.

NOTE: One of the main differences between a single and dual diaphragm booster is simply that a dual diaphragm booster offers more pedal assist.

What size master cylinder should you use?

One common misconception is that a larger bore size will generate more fluid pressure. The fact remains that a larger bore master cylinder will create more displacement; however fluid pressure will increase with a smaller bore size, as a larger bore size will require more force to achieve the same pressure output.

A 7" booster like Speedway part number 91031430, will accept master cylinders designed for a power brake system. They have 3 3/8” center to center mount pattern. Speedway offers a 1” bore GM style master cylinder, typically recommended for front disc/rear drum or four-wheel-disc applications under part number 91031445. We also carry a GM style 1 1/8” bore master cylinder under part number 91031440. In addition, we carry several other options in chrome, polished aluminum, and performance versions from CPP and Wilwood.

For anyone designing their own brake system, we recommend attempting to emulate what the factory design was. Particularly, using oem type designs and equipment. From the 1940's through the 1970's, the majority of vehicles produced by Ford, GM, and Chrysler used 1" to 1 1/8" bore master cylinders on average passenger cars.

10psi and 2psi residual valve uses

The main idea here is to prevent the possibility of a squishy or unresponsive pedal caused from fluid bleed-back. Our technicians recommend installing 2 psi residual valves for a disc brake circuit any time the master cylinder is mounted below the horizontal plane of the brake caliper. Drum brakes will always require a 10psi residual valve regardless of the master cylinder mounting position. Residual valves function as a one-way check valve, with the main purpose of maintaining fluid pressure at the caliper or wheel cylinder.

It's recommended that residual valves be mounted as close to the master cylinder as possible. Because drum brakes require more pressure to over-come the spring tension on the shoes, we recommend using a 10psi residual valve like part number 91031347. A 2psi residual pressure valve like part number 91031345, is installed for the disc brake circuit.

Proportioning Valves

Having the front-to-rear brake pressure balanced is essential to better braking performance. A brake proportioning valve simply adjusts pressure on a brake circuit. Most vehicles use a little less line pressure on the rear brakes to keep them from locking up in a panic stop. The actual requirement can vary from vehicle to vehicle, as many have different tire sizes and front to rear weight distribution. Our technicians recommend installing a proportioning valve on nearly every application. Speedway Motors offers part number 91031354, a fully adjustable proportioning valve to allow adjustments in line pressures.

The diagram below shows a typical streed rod brake system with the master cylinder mounted on the frame.

Products Featured in this Article

Related Articles

by Tim - Posted in Video
1 year 1 month ago
We get a lot of questions about brake kits so Tim gives a brief overview of disc brake setups.
Learn More
by Tim - Posted in Tech
5 months 12 days ago
Tim talks about the process of upgrading the factory hubs on his 1929 Roadster project with new manufacture units courtesy of Speedway Motors.
Learn More
by Kevin W. - Posted in Tech
6 months 18 days ago
Street Rod Tech Kevin W. talks about the first steps in his plans of a disc brake upgrade on his 1954 Chevy Bel Air, upgrading the pedal to an under-dash setup and adding a booster.
Learn More
by Kevin W. - Posted in Tech
6 months 19 days ago
Follow along as Speedway Tech Kevin W. updates the brakes on his Bel Air with a modern disc brake conversion kit.
Learn More
by Tim - Posted in Tech
8 months 21 days ago
Tim M. talks about the rare and hard to find Kinmont Brakes system, and what makes them so unique.
Learn More
by John - Posted in Tech Tips
5 months 12 days ago
In this Tech Tip, John confirms a customer question regarding the need for a proportioning valve on his ’55 F100 brake build.
Learn More
by John - Posted in Tech Tips
8 months 19 days ago
In this Tech Tip, John makes a few suggestions for a customer looking to update the braking system on his ’51 Deluxe.
Learn More
by Pat O. - Posted in Tech
37 days ago
Speedway Motors employee Pat O. talks about the CPP Hydroboost Brake System.
Learn More
by Zach R. - Posted in Tech
5 months 21 days ago
Speedway Tech Zach R. talks about the dropped spindles and disc brake conversion he installed on his '55 Sedan Delivery.
Learn More
by Speedway Tech Team - Posted in Tech
8 months 2 days ago
The E-Stopp Electric E-Brake is an electronic push-button activated emergency brake option where the visible element is small and compact, and can replace the traditional hand or foot-operated emergency brakes.
Learn More
Suggestions