ASE G1 Auto Maintenance and Light RepairBrakesHard
A customer reports that their vehicle's brakes feel 'grabby' and lock up easily, especially at low speeds. A technician inspects the rear drum brakes and finds that the self-adjusters are seized in an over-adjusted position. Which of the following is the MOST appropriate corrective action?
- ABleed the hydraulic system to release excess pressure.
- BFree up or replace the seized self-adjusters and adjust the brakes.
- CReplace the brake shoes and resurface the brake drums.
- DAdjust the front disc brake caliper guide pins.
Show answer & explanationAnswer & explanation
Correct answer: B. Free up or replace the seized self-adjusters and adjust the brakes.
If the self-adjusters are seized in an over-adjusted position, the brake shoes are constantly held too close to the drum, causing premature engagement, 'grabbiness,' and easy lock-up. The primary corrective action is to address the seized adjusters, either by freeing them or replacing them, and then properly adjusting the brakes.
Why the other options are wrong
- A. Bleeding the system addresses air or fluid contamination, not a mechanical issue of over-adjusted shoes.
- C. While worn shoes might eventually be replaced, the immediate cause of the 'grabby' and lock-up condition is the *over-adjusted* shoes due to the seized adjuster, not just the shoes themselves.
- D. Adjusting front disc brake components would not affect the rear drum brake's 'grabby' and lock-up condition.
Drum Brake Self-Adjuster
A drum brake self-adjuster automatically maintains optimal shoe-to-drum clearance; if seized in an over-adjusted state, it causes premature brake engagement and 'grabbiness.'
- Maintains shoe clearance
- Seized adjusters cause issues
- Over-adjustment leads to grabby brakes
Memory trick: Adjuster seized, grabby and tight, fix the adjuster to make it right!