Hydraulics Archives - Page 7 of 9 - UnderhoodService
Selling Services: Bleeding ABS Brakes after Component Replacement

Bleeding the brakes after brake components have been replaced is a step you don’t want to skip if you want a firm brake pedal. Air trapped in the lines, calipers or wheel cylinders will make the pedal feel soft and spongy. Air is compressible, so when the brakes are applied any air bubbles in the

Doing the ‘Complete’ Brake Job

Brake work continues to be a solid service opportunity for independent repair shops because brakes are items that inevitably wear out. Disc brake pads need to be replaced, and the rotors usually need to be turned or replaced. The front brakes do the most of the braking, so they receive most of the attention when

Braking Horsepower: How Much Does Your Car Have?

We all know brakes get hot, sometimes very hot. If you watch closely on race day, it’s not uncommon to see the rotor on a race car glowing bright orange. Iron is in the range of 1,700º F when orange. At the most basic level, a brake is an energy conversion device. Normally people will

Drum Brake Self Adjusters: Understanding These Ancient Devices

d bridge bolts. Opposing piston calipers are bolted to the knuckle and have pins to position the pads. Drum brakes have return springs to return the shoes to a rest position and hardware to hold the shoes to the backing plate. The shoes return to a fully retracted or rest position when the master cylinder

Subaru Brake System Service

Over the last 25 years or so, Subaru has been the top- selling all-wheel-drive car here in the Pacific Northwest. For beachcombers and skiers alike, as well as rock hounds and hikers, having all-wheel drive is a big plus. Stop-and-go commuting, and difficult mountain driving take their toll on both drivers and vehicles. Of all

What Were They thinking?

hey pick the size of the parts? What prevented them from making them bigger? What kind of tests did the parts and the vehicle have to endure to be judged ready for the market? These are all questions that go into the design of the brake system for the vehicle. These decisions are the responsibility


Disc brakes are not “self-energizing” like drum brakes, so they require more pedal effort to apply. It’s the magic of power brakes that allows a 98-lb. little old lady to bring two tons of Lincoln Town Car to a screeching halt with little more than a light caress of her foot against the brake pedal.

Twin-Piston Calipers: Are Two Pistons Better than One?

generate more torque. More torque means more stopping power. Also, by using the floating caliper design instead of an opposing piston design, engineers are able to avoid wheel clearance issues and other robust design features of the floating caliper. With a single-piston caliper, the footprint of pad is limited in some ways to the diameter

Master Cylinder Inspection

Although the mechanics of modern master cylinders seem deceptively simple, today’s dual-piston or tandem master cylinders still require the utmost in care and attention to maintain safe, reliable operation. The tandem master cylinder contains two piston assemblies; one for each axle set or diagonally located pair of brakes. Each piston assembly has two lip seals

Brake Fluid Testing, Bleeding & Flushing

Brake fluid is something that should always be changed when the brakes are relined or when replacing a caliper, wheel cylinder, brake line, hose or master cylinder. But what about other times? Should brake fluid be replaced for preventive maintenance? Most brake experts say yes! DOT 3 and DOT 4 brake fluid contains glycol ethers

Brake Fade

Brake fade is something nobody wants to experience. When you step down on the brake pedal with a certain amount of force, the vehicle should slow predictably. But when the brakes get too hot and start to fade, it takes more and more pedal effort to get the same amount of braking force. Eventually the