It may surprise you to know that a metal can containing a couple of rubber flaps is what allows you to stop your S40 so easily, but that's about all there is to a Volvo brake booster. The Volvo brake booster is one of those simple and elegant designs that really hasn't changed a whole lot since it first came out decades ago. The all-disc brake systems on modern Volvos dictate that a Volvo brake booster is standard equipment-without the Volvo brake booster, the pedal pressure needed to stop your vehicle would be unacceptable for nearly everyone. When you add in the complex safety functions that are commonplace today, like traction control and ABS, the Volvo brake booster becomes even more essential. But essential doesn't mean eternal, and the Volvo brake booster is prone to leaks and failure as the miles pile up. What generally occurs is that the rubber seals and diaphragms inside the Volvo brake booster canister dry out and become brittle, allowing the vacuum to escape. If the vacuum leaks out of your Volvo brake booster, the power source is removed and you're stuck with a rock-hard brake pedal. The safety mechanisms inherent in the Volvo brake booster mean that you can still stop your vehicle, but it's not easy. Neither is rebuilding a Volvo brake booster yourself: That's why we sell a premium remanufactured Volvo brake booster unit. Simply order the entire Volvo brake booster, unbolt the old one, and bolt on the new one. You'll restore your braking power and save yourself a ton of money when you order your new Volvo brake booster from us.