Automotive Disc Brakes

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Automotive Disc Brakes

• Denton ATC Automotive Technology

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Disc Brakes

• Disc brakes are fairly simple to work with, once
  you know the parts and their functions.
  Typically, there are 4 main parts of a system
• Mounting Bracket
• Rotor
• Caliper
• Pads

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Mounting Brackets
Mounting Brackets are used to hold the Caliper in
place. Other than keeping the surface clean and
free of rust and road grime, there is very little
to be done with this part
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Rotors
Rotors are metal discs supported by the
suspension. The Calipers clamp on to them to
slow their rotation, and then slow or stop the car
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Vented Rotor
These are the VENTS
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Vented Rotors
Vented Rotors have Fins in the spaces between
their machined surfaces. These spaces allow air
to pass through, which helps carry heat away.
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Nonvented Rotor
Non Vented Rotors are used on smaller vehicles,
and have no cooling fins
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Non Vented Rotor
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Rotor Repair
We will get back to these Rotors later concerning
what you can do as a repair on them.
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Calipers
Calipers are the housings that contain the
Pistons and the Brake Pads. The Calipers are
connected to the Hydraulic System, and hold the
brake pads to the Rotor
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Caliper Types

• There are 2 types of Calipers
• Fixed
• Floating

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Fixed Caliper

• Fixed Calipers are disc brakes that use a caliper
  that is FIXED in position and does not slide.
  They have pistons on both sides of the disc.
  There may be 2 or 4 pistons per caliper

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Fixed Caliper
Motorcycles and some import trucks and cars use
this type
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Sliding Caliper

• Much more common
• Single Piston
• Easier to work with
• On inboard side of caliper

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Clean, Floating Caliper
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Floating Calipers
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Operation
Caliper
Piston applies pressure to Inboard pad. As the
pad contacts the rotor, the caliper slides along
the pins, pulling the outboard pad into contact.
Brake Line
Brake Pads
Piston
Rotor
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Sliding caliper in operation
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Parts of a Caliper
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Seal
The rebuild kit will have a new O ring, and a
Dust Seal
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Piston
The Piston surface should be smooth and clean.
This one is pitted, and needs replaced.
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Adjustments?

• Disc Brakes will automatically self-adjust.
• As the Pads wear, the caliper piston will not
  retract as far
• This leaves a larger amount of brake fluid in the
  caliper, causing the master cylinder level to
  lower

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Caliper Slides
Notice where the brake pads and calipers slide on
the pin and the mount
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Caliper slides
Since parts need to slide, these areas should be
clean of dirt and rust,
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Cleaning Caliper
With the caliper off, I would use a wire brush to
clean the rust off, then use a brake cleaning
solvent to wash the sliding area.
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Wear Indicators
Brake pads wear, and most people never check
them. So, something was put on the pads to make
a noise, since most people will have a noise
checked out.
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Just a couple more things
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Diagnosis
Several different types of Complaints Noise Pulsat
ion Pedal travel More later
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Brake Noise
Wear Indicator
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Brake Pulsation
Usually a warped Rotor Rotor needs trued on a
brake lathe
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Pedal Travel
NO BRAKES!!!!
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Finis
Laters..
Denton ATC