What causes hot spots on brake drums?
Brake Drag When you depress your brake pedal, pneumatic power causes the brake shoes to expand outward against the inner wall of the brake drum. Instead, the shoe remains in partial contact with the drum surface. The resulting friction often leads to overheating, which in turn may cause cracking, scoring, or hot spots.
What is the most common cause of scored brake drums?
Scored Brake Drums This condition is caused by interference between the hub and drum mounting surface during installation as a result of using the wrong drum for the application or improperly cleaning the hub piloting surface prior to drum installation.
What happens when your brake drums get very hot CDL?
If your brakes (drum or disc) get really hot they will lose effectiveness. In extreme cases the lining/pads will start glazing/burning which you can smell and feel (significant loss of stopping power.)
What affect does oil contamination have on brake drum linings while braking?
Check brake-lining contamination When problems develop within the wheel, some of the lubricant may escape and come into contact with the brake-lining. When grease or oil is present on the brake-lining, abnormal brake behaviour will result.
How do I know if my drum brakes are bad?
One of the first symptoms of bad or failing drum brakes is unusual brake pedal feel. If the brake drums are worn excessively they can cause vibrations that may be felt in the pedal. Worn drums may also cause shuddering or pulsating that will become noticeable once you step on the pedal.
What parts are usually replaced on drum brakes?
Replacing drum brakes typically means replacing the brake shoes and drums, as well as related hardware. If additional parts fail the inspection, they will need to be replaced too. For example, if the wheel cylinder is leaking or not working properly, it’s replaced at the same time.
What are the four braking techniques?
Braking Techniques for Smooth Driving, Control & Reduced Stopping Distance
- Controlled braking.
- Threshold braking.
- Cover braking.
What is the best practice for releasing the brake?
Press firmly down on the brake pedal, applying as much braking force as possible without inducing a skid. If you feel any of the wheels begin to lock up, release the brake pressure slightly and re-apply. Hold firmly until you stop.
What do you need to know about drum brake inspection?
C800 5C2 P-1 • Refi nish brake drum; measure fi nal drum diameter. C626 5C3 P-1 • Remove, clean, and inspect brake shoes, springs, pins, clips, levers, adjusters/self-adjusters, other related brake hard- ware, and backing support plates; lubricate and reassemble.
What causes hot spotting on a brake drum?
Hot spotting is black spots on a drum’s surface that can appear in the following ways: 1. Over the entire surface (uniform). Figure 6.6 2. On one side only. Figure 6.7 3. In three equally distant places. Figure 6.8 4. Replace the brake drum. Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.7 Section 6 Brake Drum Failure Analysis 21 Polished or Glazed Drum
Is it normal for drum brakes to get hot?
However, my parking brake lever travels the recommended 4 to 7 clicks and it seems to activate the parking brake arm inside the shoe as designed. After a long drive, the temperature on the front disc brakes were a cool 110 F and 106 F. The temperature of the rear drum brakes were a warm 132 F and a hot 170 F. Is this normal?
What should pilot clearance be for broken brake drum?
HOT SPOTS REPLACE DRUM Figure 6.10 Figure 6.11 Section 6 Brake Drum Failure Analysis 22 Broken Bolt Flange (Brake Surface Not Cracked) NOTE: Allowable brake drum pilot clearance is 0.001-inch (0.0254 mm) to 0.007-inch (0.1778 mm). The bolting flange is broken, but the brake’s surface may not have cracked.