Tuesday, May 28, 2019

Brake Check

When it comes to cars, "go" is cool but "stop" is critical. With the summer travel season upon us, knowing that your car will be able to stop is a vital piece of information.

A lot of tire shops will check your brakes for free or a nominal fee, but knowing how to check them yourself is always a warranted skill, and seeing as I just did a brake upgrade on my race car, this is a great chance to show you what good brakes look like in contrast to badly worn ones.

Checking your brakes is a fairly quick and simple process, but you have to know what you're looking for. For a complete check, you're going to want to look at all four corners of your car. Your front brakes wear far more quickly than rear brakes though, so you're more likely to find wear there. If your vehicle makes a nasty squeal or pulls or vibrates during braking, that's an indicator of severe wear that needs immediate attention.

This basic check should catch wear before it becomes that kind of emergency, but it only works on disc brakes, however. Older drum-type brakes require a more involved inspection, but they are becoming very uncommon outside of older cars commonly owned by enthusiasts.

First, you need to remove each tire of your car to get in and see your brakes. The process for removal and installation of tires is exactly the same as changing a flat. Because I cannot stress the safety precautions enough, be sure the car cannot roll or fall.

  • Do not trust your jack to hold the car; use jack stands to keep it in the air. 
  • Chock your wheels, set your parking brake, and make sure the car is in park or first gear. 
I've had vehicles fall off jacks, and had a friend experience a jack failure that ended up with the car settling on his legs. He was lucky and was uninjured, but he was trapped and ended up sore for a few days. Safety first, safety always!

With the tire removed, the brake rotor and pads can be seen. Inspect the rotors for excessive wear. They are usually stamped with a minimum safe thickness, but if they aren't stamped, this can be found in your owner's manual or a service manual. (On my Miata, the minimum thickness is marked as 18mm, which can be seen in this picture.)

Looking at my old rotor beside the new one, the difference in thickness can very easily be seen.

The grooves and deep lip on the inside of the rotor show the extent of the wear and damage these brakes have suffered.

These new pads show the thickness of new, quality brakes. Look just above the bolt to see how thick a new pad is.

Notice how thin these worn pads are, as well as the uneven thickness from one side to the other. Even on my lightweight track car, these pads struggle to properly stop.

After you check your rotors for wear and your pads for proper thickness, check your brake fluid level. The reservoir is usually located on the driver's side of the engine compartment, between the front tire and the passenger cabin. (Check your owner's manual or service manual for specifics.) It will be marked with "Max" and "Min" fill marks; your fluid level should be easily seen and should be between these marks. Low fluid can be topped up with DOT3 brake fluid, available at your parts house. DOT4 is also available, but is usually only used in performance vehicles or high stress applications.

If any of your braking components are excessively worn, immediate attention is needed. Take your car to a qualified mechanic, or if you feel comfortable, do the repair yourself. Be very sure that your comfort comes from skill and not ego for this repair, as a faulty brake job can cause tragic accidents.


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