This project is posted in the auto section.2000 Mazda Miata Brake Job
As of this writing the car featured in this project is about 12 years old with just under 60,000 miles on the odometer. This is the first time we've performed a brake service on the vehicle.
For every picture or video we show on the Dirtyshirt site that involves lifting a vehicle off the ground we use the following protocol:
- Wheel chocks are placed on the down-hill side of at least one wheel.
- A floor jack is used to lift the car and jack stands are inserted.
- The floor jack is lowered until the jack stands bear the weight of the vehicle.
- We perform a bounce and shake test and try to knock the vehicle off the jack stands – if it's going to fall we want to know that now.
- The floor jack is left in place with its lift mechanism in the up position – if the vehicle shifts or a jack stand fails the floor jack will keep the vehicle suspended until we can escape from under or near the vehicle.
Jeff has lifted the car off the ground and removed the wheels. A pneumatic impact gun was used to remove the lug nuts but most any socket with an extension and ratchet will do the job.
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On the front brake, Jeff has removed the caliper bolts (pins), and the caliper mounting bracket.
The brake system on a car is a hydraulic system where brake fluid is used to move mechanical parts that perform braking.
For this caliper, when the brake pedal is applied fluid is pushed in to a cylinder (A) and the cylinder piston (B) applies pressure to the inside brake pad.
The caliper on this vehicle is considered a "floating caliper" and applies equal pressure to the outside brake pad via pins that allow the caliper to "float" or move during each braking operation. Thinking of a caliper as a large hydraulic clamp simplifies the theory of operation.
This illustration from www.familycar.com does a nice job of showing the components of a rotor and caliper.
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The piston protrudes from the cylinder and this protrusion increases as the old pads wear away. Since the new pads are significantly thicker than the old pads space must be created by pushing the piston back into the cylinder. This will give the new pads clearance to fit over the rotor as the caliper is moved back into position. A large pair of slip-joint pliers is being used to compress the piston, a c-clamp will do the job just as well.
Some pistons contain threads and must be screwed back into the cylinder and that was the case here. Jeff turned the piston several revolution counter-clockwise and then compressed the piston. This procedure was repeated a number of times until the caliper would slip over the rotor with the new pads installed.
Note that compressing the piston back into the cylinder is a slow and delicate process. As the piston compresses brake fluid will be pushed back into the system and the fluid level in the master cylinder reservoir will rise.
You must monitor the reservoir and siphon off brake fluid or the reservoir will overfill and begin to leak into the engine compartment. Do whatever it takes to remove this excess fluid being careful to avoid contact with paint since brake fluid is corrosive.
There are other methods for compressing the caliper piston and managing the brake fluid via bleeder screws that are not presented here.
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The caliper has been reinstalled on the front rotor and this is a close up of the upper portion of the caliper. (C) is the squeeler tab that Jeff spoke about in the video.
(D) is a spring that is present on the upper and lower portions of the caliper. The brake pads have small holes that have been drilled into the backing plates and accept small protrusions that are present on the springs.
The purpose of the springs is to push the pads out and away from the rotor after the driver has taken their foot off of the brake pedal. This prevents the pad from riding directly on the rotor during acceleration/cruising.
If you look at the full range of motion for the brake components beginning with no brake being applied to full emergency stopping the length of travel for the brake components is very, very, slight. In fact, it could probably be measured in thousands of an inch. The piston and pads will only travel a short distance when applying the brakes and the springs and pads will only travel a short distance to help keep the pads from riding on the rotor.
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Here's the lower portion of the caliper on the front wheel.
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The front rotor has been replaced and the caliper has been reinstalled on the vehicle.
The rear wheel pad replacement is performed in the same fashion as the front brake. The rear anti-drag springs are configured differently than in the front but the basic concept for replacement is the same.
