Brake Issues: Slack Adjusters, Drums, and Foundation Brake Wear
Out-of-adjustment brakes are the #1 DOT violation. We cover slack adjusters, drum wear, and air chamber sizing.
Out-of-adjustment slack adjusters
Automatic slack adjusters should maintain brake stroke automatically, but when they fail or when the foundation brake wears beyond their travel, the stroke exceeds the legal limit — an instant DOT violation and a truck placed out of service. We check pushrod stroke at each wheel, identify manual vs. automatic adjusters, and find why an adjuster stopped adjusting (often a worn cam, clevis, or the adjuster itself) rather than just cranking it down, which only masks the wear.
Drum and lining wear
Heat-cracked drums, glazed linings, and contamination (oil, grease, or DEF) reduce braking and cause pull. We measure drum diameter against the max stamping, inspect linings for thickness and contamination, and check for uneven wear that points to a stuck cam or air chamber. A drum turned past its limit or a cracked drum is replaced, not resurfaced.
Air chambers and valves
We verify the correct chamber size and stroke per axle (long-stroke chambers on steer axles), check the relay and quick-release valves, and test application and release timing. A brake that applies but won't release quickly is a relay or quick-release valve fault, not the chamber.
Our mobile diesel technicians carry the tools and parts to diagnose and fix this on the shoulder or at your yard — 24/7/365 across Colorado, Wyoming, and Texas.
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