* Worn or Damaged Brake Components: The most probable cause is worn or damaged brake components. This could include:
* Worn brake shoes: If the shoes are worn thin, there's less material to push against the drum, making the adjuster feel like it's fully tightened even though it isn't effectively holding the drum.
* Damaged or worn return springs: These springs pull the shoes away from the drum. If they are broken or weak, the shoes won't retract properly, leaving the drum constantly contacting them.
* Seized or rusty adjuster: While you've turned the adjuster, it may be internally seized or corroded, preventing it from fully tightening. The adjuster might be turning but not actually moving the shoes enough.
* Damaged drum: A damaged or warped drum can prevent proper shoe contact and adjustment.
* Incorrect Adjustment Procedure: It's possible you're not adjusting the drum correctly. There's usually a specific procedure to follow which involves properly backing off the adjuster, then slowly tightening it while working the shoes.
* Parking Brake Cable: A partially engaged or stuck parking brake cable can put additional pressure on the shoes, preventing the adjuster from effectively working.
Troubleshooting Steps:
1. Inspect the Brake Shoes: Remove the drum completely and carefully inspect the brake shoes. Check for wear, damage, and the condition of the return springs. Replace them if necessary.
2. Check the Adjuster: With the drum off, try manually moving the adjuster. If it's stiff or doesn't move smoothly, you might need to lubricate it (with a brake parts-compatible lubricant) or replace it. A seized adjuster will need replacing.
3. Inspect the Return Springs: Make sure the return springs are intact, not broken or stretched out.
4. Inspect the Parking Brake Cable: Make sure it's released completely and that it isn't binding or stuck.
5. Inspect the Drum: Check the drum for scoring, warping, or damage. A damaged drum will need to be replaced.
6. Consult a Repair Manual: A repair manual specific to your 1999 Chevy Tracker will have detailed instructions and diagrams for adjusting the rear brakes.
Important Note: Working on brakes is crucial for safety. If you're not comfortable performing these repairs yourself, take your vehicle to a qualified mechanic. Improperly adjusted brakes can be extremely dangerous.
