Do you have a brake pedal that feels hard to press?

You may have a bad booster, booster hose, or check valve. In this 'How To' post, we offer a simple checklist to help you diagnose potential causes of a hard brake pedal.

Drivers who are experiencing a stiff brake pedal have good reason to look over the entire brake system carefully. We created this 4-part series to help pin-down and even potentially eliminate some issues that could make your brake pedal feel like you are standing on a brick.

If your hard brake cause can’t be identified in the most obvious places we previously wrote about:

• Part 1 - vacuum pressure in the booster
• Part 2 - valving - especially pressure differential valve
• Part 3 - your pedal ratio

...then something else within your brake system must be the cause.

If it's not related to the “top 3 reasons” behind a hard brake pedal, there are several additional possible problem spots for you to examine and troubleshoot. A thorough inspection of the whole system should help you identify any such underlying issue.

Properly operating brakes are essential for safety. One thing that would make your brakes UNSAFE is the inability to depress the pedal because it is way too stiff! Fortunately, if you know the right places to check, a hard brake pedal is something you might be able to troubleshoot and fix yourself. To help you out, let’s continue this 4-part series on diagnosing and solving issues of brakes that can’t be applied because the pedal is too stiff to compress!

Previously in this series, we addressed a hard brake caused by a tripped pressure differential valve, as well as insufficient vacuum pressure creating a too-hard brake pedal. Here in part three, we take up pedal ratio – essentially the relationship between your brake pedal length and where it pivots – an issue that comes to light with some regularity when drivers experience a hard brake.

We started this 4-part series examining possible vacuum pressure as the cause of a hard brake by picturing a driver's inability to apply his brakes in traffic because the brake pedal is too stiff - requiring an inordinate amount of pushing power. An extreme scenario for sure, but the horror of a hard brake pedal can strike at any time. In power booster equipped vehicles, the issue is more common than you may think. Fortunately, you don’t need a degree in Rocket Science to diagnose and fix the glitches that are hardening your pedal.

Here’s a scary scenario we all dread as drivers. You’re cruising down the highway, wind flowing through your hair and “Born to be Wild” pumping from the stereo. Up ahead traffic begins to slow and you gently tap the brakes. To your horror, nothing happens! The pedal is stiff as a plank of wood. You have to practically stand on the brake to slow the vehicle down, but it does so eventually. Phew!

This post on vacuum pressure is the first of our 4-part series in which we take a deep dive into diagnosing the most frequent causes and solutions related to a hard brake pedal.

Vacuum Pressure

Vacuum - or really lack of vacuum pressure - is the most common cause of a hard brake pedal, and therefore the first thing to look at when a hard pedal is present. Any brake booster (whether from Master Power or any other supplier) needs a vacuum source to operate. In gasoline-powered cars, the engine provides a partial vacuum suitable for the brakes' power booster. The booster requires 18” of vacuum to operate at full efficiency.