The 10 Best Brake Bleeders
Editor's Notes
March 17, 2021:
There are a few styles of brake bleeder to look out for, and they're each tailored to a slightly different use case. The Motion Pro Hydraulic is about as simple as they get, as it's nothing more than some hose attached to a one-way check valve. The Phoenix Systems V-5 is a step more complicated and effective thanks to its hand-pump design, although it's not durable enough for frequent use. Tank-style models like the Mityvac MV6835, Capri Tools CP21029, and commercial-grade GearWrench Tank utilize compressed air in order to remove most of the hard work involved. Meanwhile, the Power Probe Master Kit remains highly ranked because of its impressive build quality and suitability for full-time use.
Because there have been no significant changes to brake bleeders in the recent past, our recommendations for this category have not changed this time around.
September 05, 2019:
When it comes to automobile maintenance, there are many considerations to be aware of. For example, you may have to periodically put either a synthetic or diesel variety oil into your engine to keep it running smoothly. Or, you might need to use an automotive tool set to tighten components under the hood. Potential leaks, low fluid levels, and improper maintenance can also introduce air into to your vehicle's brake system, which you definitely don't want, either. Neglected brakes can reduce pedal power and compromise your mileage and safety! For that reason, the process of brake bleeding and fluid replacement is an important part of car maintenance. The good news is that our list of bleeders provides you with the tools needed to perform this action on your own.
For example, the Power Probe Master Kit includes 12 aluminum and cast iron adapters, each of which are color-coded for use on a variety of vehicle types. I also included the Capri Tools CP21029 for its vacuum operation to flush and drain both hydraulic brakes and clutches. The built-in hand pump and pressure gauge on the Motive Products Power allows for plenty of control and precision when bleeding brakes from most late-model GM vehicles. The Mityvac MV6835 is one of the few options equipped with a variable control thumb throttle, which helps to optimize fluid flow rate. Its molded base also supports bench mounting. I also added the GearWrench Tank for its 4-gallon capacity and built-in diaphragm, which helps to keep air and fluid separate. It also has an automatic shutoff function. The Ares 70923 offers a transparent drain hose and locking trigger for completely hands-free operation. I thought the Phoenix Systems V-5 was a worthy contender, thanks to its patented reverse bleeding operation, leveraging gravity to force air up and out of a brake line. Finally, while the Allstar Performance Bottle may not be powerful enough for large vehicles, its sturdy silicone hose always stays in place, while the translucent design makes it easy to monitor the color of your brake fluid as it fills the reservoir.
A Brief History Of Brakes
At a certain level of performance, physically stopping a car became impossible without additional mechanical aid.
Inspired by horse-drawn carriages, the first brakes were nothing more than a wooden block pressed against the leather or metal that served as a primitive tire. Once cars exceeded 20 miles per hour and began using pneumatic tires, however, this "spoon" method was no longer effective, and served only to destroy rubber. The drum braking system became popular and would, in fact, come standard on many models for several decades. As the power of these braking mechanisms increased, so too did the force required of the driver. At a certain level of performance, physically stopping a car became impossible without additional mechanical aid. The early lever systems often fed inconsistent pressure to the different wheels, which is an easy way to lose traction and spin out, even today.
Around the turn of the 20th century, hydraulics crept onto the scene along with disc brakes. In 1898 (seemingly a hundred years ahead of his time), Elmer Ambrose Sperry designed an electric car with a metal caliper that pinched the wheel's rim in order to grind to a halt. It wouldn't take long for Frederick Lanchester to add the rotor, a smooth piece of metal meant just for stopping, and the first disc brake came into being — complete with a truly horrific screeching sound, due to its copper-on-steel contact point. Asbestos came to the rescue as engineers constructed blocks of interwoven fiber and copper wire, mitigating the horrific, copper-on-steel screeching, and adding a new level of sensitivity to braking. Yet it wasn't until the 1950s that discs would claim a large share of brake systems in new cars.
The Safest Way To Slow Down
While the concept has been around for over 100 years, today's brakes are quite different from the first units installed on passenger cars. The vacuum booster affords mere humans the incredible levels of torque needed to slow down a 4,000-pound chariot. The design of drum brakes borrowed power from the wheels themselves to help slow the car, but hydraulically-controlled discs have no such added leverage. To rectify this, modern brakes take advantage of the engine's inherently-produced vacuum to multiply the force applied to the pedal. Divided by a diaphragm and valve, this two-chambered device moves the master cylinder's piston, forcing hydraulic fluid through the lines and ultimately closing the calipers.
A controller instructs the respective valves to open and shut rapidly, briefly cutting torque to the wheel in question and allowing its tire to regain traction.
There are a handful of fail-safe features built into modern-day brakes. The one-way check valve prevents any air pockets in the vacuum booster in which it's seated, ensuring that the booster retains enough pressure for a few solid pumps of the brake, should the engine give out. Additionally, most systems utilize two hydraulic circuits, with two wheels on each. If one fails due to a leak, the driver still has enough stopping ability to prevent disaster.
Anti-lock brakes actually evolved out of the aviation industry, developed to keep planes moving safely during taxi and takeoff. In the 1950s, the technology was adapted to the ever-dangerous motorcycle, and over two decades, ABS was refined into a reasonable, functional safety feature worth the top manufacturers' attention.
Modern ABS consists of a combination of sensors that work together to determine when a wheel starts to skid. A controller instructs the respective valves to open and shut rapidly, briefly cutting torque to the wheel in question and allowing its tire to regain traction. Anti-lock brakes are yet another of humanity's mechanical systems that perform objectively better than a human being possibly can. Thankfully, this lifesaving system is included in a large number of cars today.
When Friction Takes Its Toll
Nothing is forever, least of all a component that uses friction to corral a multi-ton beast made of metal and plastic. Shoes, which provide friction to low-cost or antiquated drum brakes, wear down and eventually have almost no effect on momentum. When disc brakes go bad, it typically starts with worn or uneven pads. Contrary to popular belief, rotors do not actually warp, as they simply don't get that hot. Carbon and other deposits stick to the rotor, causing grooves and reducing efficiency. The surface erodes, exposing the pad's rivets, and when those high-hardness fasteners start to rub on the rotor, you will notice every time you touch the pedal. Aside from decreased stopping ability, uneven or overused pads can quickly damage the rotor and cause lock-up. Extreme vibrations can cause permanent damage to steering, suspension, and transmission components, and can even crack the frame or dislodge important nuts and bolts.
Aside from decreased stopping ability, uneven or overused pads can quickly damage the rotor and cause lock-up.
A brake job is one of the most common repairs made to vehicles, and yet it's not entirely simple. In order for the system to work, it's imperative to keep the actual brake line free of air pockets, which compress and seriously hurt braking performance. While the check valve keeps the vacuum booster free of such gases, the high-pressure side of the system requires an exacting installation process that involves eking the last, tiniest bits of atmosphere from the lines, an operation known as bleeding.
Traditionally, bleeding brakes is a two-person job. Each caliper contains a bleeding screw at its highest point, because air is lighter than oil, and when that screw is loosened slightly, it allows fluids to escape the caliper until it's tightened again. Brake bleeding kits employ a pump, reservoir, and lengths of tubing to allow the solo mechanic to circulate the fluid, bubbles and all, while forcing the air out, and refilling the system via the master cylinder. They all operate on basically the same concept, but they do differ slightly in how their valves and pumps operate. Primarily, you should consider larger reservoirs and powered pumps if you're working on large vehicles, or performing multiple brake jobs. Proud owners of a single mid-size sedan, on the other hand, can likely get by with a smaller, inexpensive model. As long as it's reliable and leak-free, a brake bleeder can save you considerable headache, while also sparing the skin on your knuckles.