Drum Brake Inspection — What to Check and When to Replace

A drum brake hides its wear. Unlike a disc brake, you cannot see the friction material without removing the drum, so problems are usually noticed as a weak parking brake or a long pedal rather than as visible wear. This article covers what to inspect once the drum is off.

Drum brake ၏ ဟောင်းနွမ်းမှုကို drum မဖြုတ်ဘဲ မမြင်ရပါ။

1. Signs from the driver's seat — မောင်းနှင်စဉ် လက္ခဏာ

• A parking brake that needs many clicks, or will not hold on a slope
• Longer brake pedal travel than before
• The vehicle pulling to one side under braking
• Grinding or scraping from a rear wheel
• Brake fade after repeated heavy braking, especially loaded or on a long descent

2. With the drum removed — Drum ဖြုတ်ပြီးနောက်

1. Lining thickness — measure the friction material remaining and compare against the manufacturer's minimum. Replace if it is at or near the limit, or if the rivets are close to the surface.
2. Contamination — oil or brake fluid on the lining cannot be cleaned off. If the lining is soaked, the shoes are scrap and the source of the leak must be fixed.
3. Wheel cylinder — peel back each rubber boot. Any fluid behind it means the cylinder is leaking and must be replaced.
4. Drum condition — check for scoring, cracks, heat bluing and a wear ridge at the edge.
5. Drum diameter — measure it and compare against the maximum diameter cast or stamped into the drum. A drum machined beyond that figure is too thin to shed heat safely and must be replaced.
6. Springs and adjuster — check the return and hold-down springs for stretching or heat discolouration, and check the adjuster turns freely.

Drum ပေါ်တွင် ရိုက်နှိပ်ထားသော အများဆုံး အချင်းကို ကျော်လွန်ပါက drum အသစ် လဲရမည်။

3. What to replace together — အတူတကွ လဲရမည့်အရာ

• Shoes always as a complete axle set, both sides together, never one wheel alone.
• Return and hold-down springs with the shoes. Springs lose tension with heat, and a weak return spring leaves the shoes dragging, which overheats the drum and wears the new lining quickly.
• The wheel cylinder if there is any sign of seepage. The labour is already done.