Both field and laboratory test results repeatedly prove that the friction lining on a disc brake pad can wear to within a millimeter of the mating surface of the disc brake shoe without affecting brake function, provided the entire surface area of the friction lining material remains intact during contact with the rotor.
In 1966, disc brakes were starting to be offered on a wide variety of vehicles. The problem was that fixed opposed piston calipers were very heavy and expensive. Also, they were overkill for most common vehicles of the day.
Hydro-boost brake boosters can be mysterious to the untrained technician because part-swapping will not solve some brake issues. These systems use the pressure of the power steering pump to power the brake booster. The booster is essentially a power steering unit that supplements the driver’s input.
On a mechanical level, it is easy to understand how brakes work. We all understand that brake fluid transfers force from one hydraulic component to another. But, how does this apply to how a brake pedal feels? This is where math is required.
There are many opinions on bedding. Some manufacturers say it is not needed while others say it is an absolute necessity. Bedding is a process by which a thin layer of friction material from a set of new brake pads gets transferred to the rotor surface. This practice that many professionals let slip by can help improve the performance and quality of any brake job.
Sticking caliper pistons, rusty brackets and bad brake hoses can all cause brake pulls, but don’t assume they are the only things that can. If the problem is constant pull, it is typically easier to diagnose. Don’t forget to inspect suspension parts, such as bushings, that allow wheel movement under braking.
Although it is impossible to determine what repairs might be needed until the brake assemblies are inspected, a preliminary road test can help pinpoint problems. During the road test, listen for noises and note any pedal pulsation or vehicle pulling when applying the brakes.
The digital version of the May issue of Brake & Front End magazine is available online. Click to access the easy-to-view digital version that features articles on brake pad wear, hydro-boost, Chevy Cobalt alignment, ride control, BMW air ride, ASE A5 exam, TPMS, bearings, a host of tech tips, and more!
Modern brake pad wear sensors can do more than just warn the driver of a worn brake pad. These new wear sensors work with the rest of the brake system and can estimate the mileage until the brake pads wear out.
We are in the midst of one of the most interesting transformations our industry has ever seen. There is an unprecedented amount of cooperation occurring throughout the industry and that’s a good thing. There is also a number of substantial and disruptive changes coming.
According one recent tire dealer survey of the top tire sizes sold, only one 15-inch size cracked the top 10. Since tires are changing and not the roads, something has to give. These stock wheel and tire packages with less sidewall are being use to reduce hysteresis losses that lead to rolling resistance. If there is less sidewall to flex, less fuel is consumed by the engine to flex the sidewall.
For the BMW 7 Series E65/E66 manufactured between 2001-’08, engineers went with an innovative rear air ride system. The Dynamic Drive system that uses active anti-roll bars to keep the vehicle level was standard on these models. Some of these vehicles have optional Electronic Dampener Control (EDC) that tunes the compression and rebound of the dampener to the movement of the wheels and body for the best possible ride.