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 - 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.