No room for error when it comes to repairing brakes
`Close enough' is just not good enough in systems where clearances are tight
If you're buying slippers, toques or sweaters, a close fit is good enough. Other things in life require a very precise fit.
Brake rotors on your car or truck are built to a specific size and shape. Get these wrong, and they may not work at all.
Dawn Mueller is a good friend, and a service adviser at a car dealership in Northern Ontario. Recently, she told me a story that illustrates the importance of using the proper parts, of the proper size, if you decide to do a brake job on your car or truck.
One of Mueller's customers stopped in with a nearly new crossover that was in some serious need of help, not long after he'd attempted to do his own brake job.
The two-year-old vehicle arrived on a tow truck, and was dragged into the shop with a single rear wheel that was locked solid. This left a 20-foot skid mark on the shop floor, complete with gouges from its recently installed studded winter tires. The locked-up wheel was the result of the customer's badly botched brake job.
“He sourced his own parts from the internet, but selected the wrong rear brake rotor for the job,” Mueller said.
“There are two rear brake rotors available for this model, and they're extremely close in diameter to one another. With the naked eye, you'd hardly be able to tell the difference.”
A brake rotor is a precisely sized round metal disc that's responsible for much of your vehicle's ability to stop. The rotor spins in sync with the vehicle's wheels, while the brake caliper, pads and other components float over it with minimal clearance.
When you brake, the caliper squeezes the brake pads against that spinning rotor, generating the friction required to stop the car. Clearances in this system are very tight, and that's why it's extremely important for the installed brake rotor to be exactly the right size. There's no room for error.
Mueller's customer had ordered and installed a rotor that was just slightly too large.
“If he had ordered the parts from my counter, we'd have crosschecked against the VIN (vehicle information number) of his vehicle to make sure he had the right parts, the first time,” she said. “Buying online, you've got to be careful, as you don't always have an experienced professional double-checking that you're getting the proper part.”
The real kicker in this situation is how close in size the two possible rotors are. Though the customer was able to physically fit this slightly-too-large rotor into place, reinstalling nearby components would have been a frustrating and exhausting experience.
“A professional would have caught the problem immediately,” Mueller said. “Without years of experience working on brakes, this customer didn't see an issue, and forcefully proceeded with the installation.”
After eventually finagling and forcing his rear brakes back together with (we assume) a lot of struggle and swearing, the customer drove the vehicle.
Not surprisingly, the rear brakes made some awful noises from the get-go, and they didn't last long before total failure caused the rear-wheel lockup situation that brought the machine into the shop.
The result? Bent and broken brackets aside, the replacement brake rotor was also destroyed — but not before it machined its way into the nearby caliper saddle, damaging that as well. The brake rotor then failed structurally and broke it into two pieces.
“This is what happens when you don't know what you're doing, and become frustrated and angry, and wind up breaking things when you try to force them back together,” Mueller said.
“Thankfully, there was no accident and nobody was hurt.
“Brakes should be serviced and cared for in a specific way, by an experienced professional. In this case, the customer was trying to save a few dollars, but the repair bill to fix the damage he caused is presently at $2,000, and counting.”
Buying online, you've got to be careful, as you don't always have a ... professional double-checking that you're getting the proper part.