Brake systems are vital components that directly affect a vehicle's safety. Drum brake systems, in particular, are commonly used on the rear wheels of many passenger vehicles due to their reliability and cost-effectiveness. However, since these systems have a more enclosed structure compared to disc brakes, problems are often detected late, and neglected maintenance can lead to serious safety risks.
In this article, we explain the necessary steps for proper maintenance of drum brake systems, common mistakes, and the precautions that drivers and technicians should take.
What is a Drum Brake System?
A drum brake system consists of a closed drum structure whose inner surface comes into contact with brake shoes. During braking, the shoes press against the drum surface to slow the vehicle. The system generally consists of return springs, pressure springs, a wheel cylinder, a handbrake cable, and brake shoes. Each of these parts should be regularly inspected, cleaned, and replaced if necessary.
Periodic Drum Removal and Cleaning
One of the most frequently overlooked maintenance tasks in drum brake systems is removing the drums periodically and cleaning the inside. Over time, accumulated brake dust creates contamination on the surface, negatively affecting braking performance.
Key points to consider
- The drum should be removed during every service and cleaned inside with brake cleaner spray.
- Brake shoes should be sanded lightly; if glazed, they must be replaced.
- Shiny or worn areas inside the drum should be visually inspected; if there is excessive wear, the drum should be turned or replaced.
Common Issues with Brake Shoes
Drum brake shoes wear down over time. However, in some cases, dangerous issues may occur such as the lining separating from the shoe or noise during braking. Especially glued linings can loosen and detach due to heat exposure.
Recommendations:
- Riveted linings should be preferred when possible.
- Shoe mounting points (springs, bolts) should be checked and tightened if loose.
- During installation, care should be taken to center the shoes and ensure compatibility with the wheel cylinder.
How to Properly Adjust the Brakes?
In drum brakes, adjustment is needed to keep the shoes at the ideal distance from the drum. This is usually done through the “John hole” at the back of the drum using a screwdriver. If adjustment is not made, the brake pedal may feel loose or braking may become unbalanced.
Points to consider during brake adjustment:
- Before mounting the drum, check the tension of the handbrake cable.
- If the shoes are new, there may be tightness while installing the drum; clearance should be provided using the adjustment screw.
- If the drum spins freely but braking is weak, the gap between the shoe and drum may be too large.
Wheel Cylinder and Hydraulic Leak Inspections
The wheel cylinder pushes the brake shoes against the drum during braking. As one of the end points of the hydraulic system, its sealing is crucial. A leaking cylinder reduces both brake performance and brake fluid levels.
Inspection and maintenance suggestions:
- Visually inspect around the wheel cylinder for any signs of fluid leakage.
- If there is deformation or cracking in the cylinder rubbers, the part must be replaced.
- At each service, the brake fluid level should be checked, and air should be bled if needed.
Importance of the Handbrake Mechanism
In drum brake systems, the handbrake mechanically engages the brake shoes. The handbrake cable may loosen or break over time, creating rollback risks when the vehicle is parked.
Important points to consider:
- Check whether the brake shoes engage when the handbrake lever is pulled.
- Cable tension should be adjusted via the adjustment bolt.
- As the handbrake mechanism works in integration with the brake shoe assembly, it must not be neglected during maintenance.
Additional Details to Watch in Drum Brake Systems
- If the brake boosters (master cylinders) are replaced, both sides should be renewed together. Replacing only one side disrupts the system balance.
- Spring and pin mechanisms should be inspected every time; worn springs must be replaced.
- The drum hub connection should be cleaned with rust remover and fine grease to prevent the drum from seizing.
- During maintenance, users should specifically request the rear brake system to be opened. The condition of drum brakes cannot be determined by visual inspection alone.
Conclusion
Proper maintenance of drum brake systems not only extends component life but also directly affects driving safety. Issues such as shoes detaching, sudden locking during braking, or loss of braking can have serious consequences.
Technicians should open both sides during maintenance and not rely on visual cleaning alone; users should request special attention to the brake system during standard service. Neglecting the brake system can result in irreversible outcomes. Therefore, both users and technical services must exercise maximum caution
