Jalopnik guts a Jeep CJ to show the science behind what makes our vehicles stop.
Some teach by reading from a book. Others teach by telling stories. Then there are those who teach by being hands-on and getting some dirt under their nails. Jalopnik‘s David Tracy is that kind of teacher, and he uses an old Jeep to educate his viewers.
In the above video, the former FCA man who led the design of the powertrain cooling system for the JL Wrangler is on a mission to find a junkyard vehicle with a brake system that’s easy to extract.
He plans to use it to show how brakes work from pedal push to full stop. Tracy comes across a CJ and proceeds to remove its brake booster, master cylinder, brake pedal assembly, and rotor/caliper setup. He takes the dirty, forgotten hardware back to his shop, rust, and gunk staining his hands.
Then he breaks things down. Here’s the gist of his explanation:
1.) When you push down on your brake pedal, the long lever arm it’s connected to gives you a mechanical advantage that’s useful when trying to push a rod through your brake booster.
2.) So is the negative pressure created by your engine’s piston’s moving down to suck in air. The pressure pulls the rod even further through the booster and into the brake master cylinder.
3.)That has a piston that pushes brake fluid through the metal brake lines that eventually connect to rubber lines, which feed into the brake pistons. Given that pressure is force over area and the brake pistons have a larger area than the master cylinder’s piston, they deliver another mechanical advantage. They use that to make the calipers clamp the brake pads down on the discs and bring the vehicle to a halt.
Tracy teaches an important and interesting lesson. We would say someone should teach him one about hand cleaners that can take rust and grease off, but we have a feeling Tracy already knows it well.
Derek Shiekhi's father raised him on cars. As a boy, Derek accompanied his dad as he bought classics such as post-WWII GM trucks and early Ford Mustang convertibles.
After loving cars for years and getting a bachelor's degree in Business Management, Derek decided to get an associate degree in journalism. His networking put him in contact with the editor of the Austin-American Statesman newspaper, who hired him to write freelance about automotive culture and events in Austin, Texas in 2013. One particular story led to him getting a certificate for learning the foundations of road racing.
While watching TV with his parents one fateful evening, he saw a commercial that changed his life. In it, Jeep touted the Wrangler as the Texas Auto Writers Association's "SUV of Texas." Derek knew he had to join the organization if he was going to advance as an automotive writer. He joined the Texas Auto Writers Association (TAWA) in 2014 and was fortunate to meet several nice people who connected him to the representatives of several automakers and the people who could give him access to press vehicles (the first one he ever got the keys to was a Lexus LX 570). He's now a regular at TAWA's two main events: the Texas Auto Roundup in the spring and the Texas Truck Rodeo in the fall.
Over the past several years, Derek has learned how to drive off-road in various four-wheel-drive SUVs (he even camped out for two nights in a Land Rover), and driven around various tracks in hot hatches, muscle cars, and exotics. Several of his pieces, including his article about the 2015 Ford F-150 being crowned TAWA's 2014 "Truck of Texas" and his review of the Alfa Romeo 4C Spider, have won awards in TAWA's annual Excellence in Craft Competition. Last year, his JK Forum profile of Wagonmaster, a business that restores Jeep Wagoneers, won prizes in TAWA’s signature writing contest and its pickup- and SUV-focused Texas Truck Invitational.
