Maintaining the braking system in your classic MG is crucial for safety and performance. If you’re noticing your 1979 MGB’s handbrake pulling up too far, or the rear brakes feeling less responsive, it might be time to adjust your rear drum brakes. This guide will walk you through the process of adjusting your MGB’s rear drum brakes, even if you’re new to car mechanics. You’ll discover how to use a Mac Car Hand Tool Rear Drum Brake Adjuster (commonly known as a brake adjuster wrench) and other tools to keep your vintage vehicle stopping safely.
Understanding MGB Rear Drum Brakes and Adjustment
The 1979 MGB, like many classic cars, utilizes drum brakes on the rear wheels. Drum brakes operate using brake shoes that press outwards against the inside of a rotating drum to create friction and slow the vehicle. Over time, as the brake shoes wear down, the gap between the shoes and the drum increases. This increased gap reduces braking efficiency and requires adjustment to restore optimal performance. The rear drum brake adjuster mechanism is designed to compensate for this wear, allowing you to manually adjust the brake shoes closer to the drum.
Essential Tools for Rear Drum Brake Adjustment
To adjust your MGB’s rear drum brakes effectively, you will need a few essential tools:
- Rear Drum Brake Adjuster Tool (or Wrench): This specialized tool is designed to engage with the square adjuster on the rear of the brake drum. While a specific mac car hand tool rear drum brake adjuster is ideal, a small 1/4″ drive 3/8 socket and ratchet (used unconventionally as described in the original forum) or a small crescent wrench can also work.
- Jack and Jack Stands: Safety is paramount. You’ll need a reliable jack to lift your MGB and sturdy jack stands to support it securely.
- Wheel Chocks: Place wheel chocks in front of the front wheels to prevent any accidental rolling.
- Gloves and Safety Glasses: Protect your hands and eyes during the process.
- Penetrating Oil (Optional but Recommended): Especially for older vehicles, penetrating oil can help loosen any rust or corrosion on the adjuster mechanism, making it easier to turn.
Step-by-Step Guide to Adjusting Your MGB Rear Drum Brakes
Follow these steps to safely and effectively adjust the rear drum brakes on your 1979 MGB:
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Safety First: Park your MGB on a level surface. Engage the parking brake firmly and place wheel chocks in front of the front wheels. Loosen the lug nuts on both rear wheels, but do not remove them yet.
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Raise and Secure the Vehicle: Using your jack, raise the rear of the MGB and place it securely on jack stands positioned under the rear axle. Ensure the car is stable before proceeding. Once secure, release the parking brake completely.
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Locate the Brake Adjuster: Crawl under the rear of the car and locate the square adjuster on the backing plate of each rear brake drum. It’s usually found on the rear side of the drum assembly.
Rear drum brake adjuster location on MGB -
Adjust the Brakes – Tightening: Using your mac car hand tool rear drum brake adjuster (or chosen alternative), engage the square adjuster. Turn the adjuster in a clockwise direction (or as if you were tightening a standard bolt). As you turn, the brake shoes will move outwards, tightening against the drum. Continue turning until the wheel becomes difficult or impossible to rotate by hand. You will feel resistance as you try to spin the wheel.
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Adjust the Brakes – Backing Off: Once the wheel is locked, begin to back off the adjuster by turning it in the opposite direction (counter-clockwise). Turn the adjuster incrementally, checking the wheel rotation after each small adjustment. The goal is to back off the adjuster just enough so that the wheel rotates freely with a slight, consistent dragging sound from the brake shoes. As mentioned in the forum, you might feel flat spots every 90 degrees of rotation on the adjuster; aim to stop at one of these flats after backing off.
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Repeat on the Other Side: Repeat steps 4 and 5 on the opposite rear wheel. Ensure both sides are adjusted similarly for balanced braking.
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Check Handbrake Adjustment: After adjusting both rear brakes, lower the car back to the ground and tighten the lug nuts to the correct torque specification. Now, test the handbrake. Pull the handbrake lever up gradually. Ideally, the handbrake should firmly lock both rear wheels when pulled about halfway through its full travel. If the handbrake still pulls up too far without effectively locking the wheels, you may need to further investigate the handbrake cable or the rear brake mechanisms.
Troubleshooting Common Issues
- Stuck Adjusters: Corrosion and rust can seize the adjuster mechanism, making it difficult to turn. If you encounter a stuck adjuster, apply penetrating oil generously and let it soak for some time. You can also try gently tapping the adjuster housing with a hammer to help loosen it. In stubborn cases, applying heat with a torch (carefully!) might be necessary, as suggested in the forum, but proceed with caution and be mindful of brake lines and flammable materials.
- Stripped Adjusters: If the square adjuster is damaged or stripped, your mac car hand tool rear drum brake adjuster may not engage properly. In this case, you might need to use a different tool like a small crescent wrench, or ultimately replace the adjuster assembly.
Conclusion
Regularly adjusting your MGB’s rear drum brakes is an essential part of maintaining your classic car’s safety and driving performance. By following these steps and using the appropriate mac car hand tool rear drum brake adjuster or alternatives, you can ensure your brakes are functioning optimally. Remember to always prioritize safety and consult your MGB workshop manual for specific details and torque specifications related to your model year. Proper brake maintenance not only keeps you safe on the road but also preserves the joy of driving your classic MG for years to come.
