* Parking brake mechanism: A problem with the parking brake, such as a cable that's stuck, a seized caliper, or a problem with the parking brake release mechanism itself, can cause the rear brakes to drag. This is a common cause of rear brake grab.
* Seized brake caliper(s): A caliper piston can seize in place due to corrosion, rust, or a lack of lubrication. This prevents the caliper from properly releasing the brake pads, leading to constant pressure on the rotor. This is also a very common cause.
* Brake lines or hoses: A restricted brake line or a hose that's internally collapsing can prevent proper brake fluid flow to the rear brakes. This could cause uneven pressure and lead to one side or both rear brakes grabbing.
* Wheel cylinder(s) (if drum brakes): If your Suburban has rear drum brakes (less likely on a '99 but possible), the wheel cylinders could be leaking or seizing. This is similar to a seized caliper, but within the drum brake mechanism.
* Low brake fluid: While less likely to *cause* grabbing directly, low fluid can indicate a leak somewhere in the system which *could* lead to uneven pressure and potential grabbing.
* Brake pad issues: While not a primary cause of grabbing, severely worn or unevenly worn brake pads could contribute to the problem, especially in conjunction with other issues. The pads themselves won't seize, but the condition might exacerbate a caliper problem.
* Contaminated brake fluid: Brake fluid absorbs moisture over time. This moisture can cause corrosion and seizing within the braking system.
Troubleshooting Steps:
1. Check the parking brake: Make absolutely sure the parking brake is completely released. If there's any doubt, try manually disengaging it at the cable.
2. Inspect the calipers: Look for rust, corrosion, or binding around the caliper pistons. Try to manually move the caliper pistons – they should move relatively freely.
3. Check brake lines and hoses: Look for any signs of damage, leaks, or swelling.
4. Check brake fluid level: Low fluid indicates a leak somewhere in the system.
5. Check the rotors/drums for scoring or uneven wear: This could be a symptom of a grabbing brake.
Important Note: Diagnosing and repairing brake problems requires some mechanical knowledge and the right tools. If you're not comfortable working on your brakes, it's crucial to take your Suburban to a qualified mechanic. Driving with faulty brakes is extremely dangerous.
