See Details

30% Off Online Orders of Select Hard Parts. Enter Promo Code MMJ30 in Cart.

Close (X)

Receive Up To 30% Off Your Online Purchase Of Select Parts And Accessories
Use promotional code MMJ30 at checkout to receive 30% off the following categories: Select Brake Parts, Select Hi-Performance and Truck Accessories, Batteries, Paint, Splash Guards, Select Ventvisors & Bug Shields, Springs & Spacers, Water Pumps, Belts, A/C Parts, Starters, Alternators, Fuel Pumps, Radiators, Radiator Fans, Thermostats, Caps & Clamps, Clutches, Spark Plugs, Plug Wires, CV Axles, Battery Chargers & Booster Cables, OE Locks, Rack & Pinons, Window Motors, RainX Wipers, Appearance Chemicals, Floor Mats, Lift Equipment, Hand Tools, Travel Accessories, Car Covers, Seat Covers, Wheel Covers, Body Repair, Collectibles and Apparel.

Use promotional code MMJ20 at checkout to receive 20% off the following categories: Ignition, Shocks & Struts, Chassis, Jumpstarts, Air Filters, Oil Filters, Bearings & Seals, Engine Parts, Wash Accessories, Outdoor Lifestyle, Towing, Mini Air Compressors, Tire Repair Accessories, Mufflers, Grease/Oil, Additive Chemicals, P/S Pumps, Cooling Product, Timing Belts, Specialty Tools, Radiator Hose, Motor Mounts, Mirrors, Lug Nuts, Sealants/Adhesives, Fuel Filters, P/S Hoses, Gas Cans, Oil Change Accessories, Help, Wiper Motors, Loaner Tools, Air Compressors, Horns, Books, Distributors, Sun Control and Exhaust Adapters.

Use promotional code MMJ15 at checkout to receive 15% off the following categories: Test Equipment, Power Tools, Emergency Supplies, Electronics and Stereo & Accessories (MAP pricing Exclusions).

Offers not valid in combination with any other discounts, promotions or items already on sale. Not valid on gift cards, special orders, installed merchandise, commercial or fleet purchases. Those products that are included in these offers will be displayed in product search results and product detail pages. Excludes the following brands: WeatherTech, Champion, Powerstop, Razor, Traxxas, Superchips, Hypertech, Edge, Bully Dog, Diablo, Edelbrock, Holley, NOS, Proform, Specialty Auto, Autometer, Accel, K&N, Kenwood, Pioneer, Sony, Thule, Thule Karrite, JVC, Flowmaster, Hurst, B&M, MSD, Moog, Wagner, Philips and BBK Performance. Valid online until 11:59 PM EST on 11/22/17.

Receive 10% Off Wagner branded brake parts with your online purchase. Use promotional code: WAGNER10.

Receive 20% Off Select Champion branded products with your online purchase. Use promotional code: CHAMP20.

Receive 10% Off Select FelPro branded products with your online purchase. Use promotional code: FELPRO10.


Free Shipping on Orders Over $50 or in-store pickup
https://www.pepboys.com/customer_care/policies/shipping

Brake Drums

 

Brake Drums

Brake Drums are cylindrical brake system components that are shallow and drum-like in shape. They transfer friction into torque used to slow the vehicle. Drum brake components include the backing plate, brake drum, wheel cylinder, brake shoe and various springs and pins.

what is a brake drum and what does it do?

How Does it Work?

  • The brake drum fastens via a flange arranged perpendicular to the braking surface to the axle flange.
  • The inner surface of the drum rotates with the road wheel and at the exact rotational speed of the wheel.
  • When hydraulic or mechanical actuation of the brake shoes (friction) occurs, the shoes are pressed into contact with the braking surface that comprises the inner surface of the drum.
  • Friction material (shoes) contact with the drum creating interference that impedes the motion of the road wheel, thereby creating the braking action. The harder the brake pressure, the more braking power (and heat) result from the brake drum.
  • Braking force is transferred from the brake shoes through the drum and into the road wheel.

How is it Made?

  • Brake drums are almost invariably cast from a ferrous metal, either steel or iron.
  • A secondary machining process cuts a uniform mounting flange and cuts the braking surface. The braking surface is cut to be exactly perpendicular with the mounting flange.
  • Brake drums frequently have cast-in features such as fins along their outer surface to assist in cooling.
  • The finished brake drum is usually coated with an anti-rust chemical to prevent it from rusting or corroding during shipping and storage.

Why Does it Fail?

  • Brake drums most frequently fail due to wear.
  • Every brake drum has a cast-in number representing the largest acceptable measurement diameter. Drums may be “cut” on a special lathe to eliminate friction wear grooves and scoring. If a drum cannot be cut to a dimension smaller than the maximum, the drum must be replaced.
  • Excessive heat, that can be caused by operating the vehicle with the parking brake left on, can cause the drum to warp or crack. If your drums warp or crack and cannot be cut into specification, it will be necessary to obtain replacement brake drums.
  • Severe rust will compromise the strength of a brake drum and therefore any drum that is severely rusted should be replaced.

What are the Symptoms of Failure?

  • A brake drum with an inner diameter measurement along the friction surface that is greater than that value cast into the drum flange is failed.
  • A brake drum with a visible crack has failed and must not be reused.

What are the Implications of Failure?

  • Drums that are cut beyond the safety maximum diameter are thin, do not have adequate structural strength, and are unable to dissipate heat properly. Such a brake drum can fail without warning and are not safe.
  • Out-of-round brake drums that cannot be adequately machined reduce braking effectiveness and are not safe to drive on.

How Difficult is the Install?

Difficulty Rating:

Related Parts

Return to Parts Guides