What is the reason for the car still rolling after pulling the handbrake?

[McJackson]

If the car still rolls after pulling the handbrake on a steep slope, this situation is definitely abnormal. The reason may be that the handbrake has some slack, and you can try to tighten the handbrake cable. If you find that the braking performance or sensitivity of the handbrake is poor, it can be resolved by adjusting the operating copper cable of the handbrake. At the connection point between the bottom of the handbrake handle and the copper cable (usually covered by interior trim), there is an adjustable compensation mechanism. By loosening the lock nut with a wrench, you can stretch the length of the brake copper cable. Here are some methods to deal with a rolling car: 1. When you find the car rolling, you should immediately stop it using the handbrake or foot brake. After stopping, place triangular wood blocks, stones, etc., under the rear wheels before starting again. 2. If the car's brakes cannot stop the vehicle, pay attention to controlling the direction to avoid pedestrians or dangerous objects on the road, and then move the rear of the car closer to natural obstacles on the roadside, using them to prevent the car from sliding further.

[LaBrady]

When I first bought my car, I also encountered this situation. It was really scary when the car still rolled forward after pulling the handbrake. Common reasons include the handbrake cable being loose or improperly adjusted, meaning there's too much slack when pulled, resulting in insufficient tension. Another possibility is that the rear brake pads are worn too thin, making the cable tension ineffective. If the rear brake discs get wet and freeze after rain or snow, or if oil drips onto the drum brake shoes during previous repairs, slipping can occur. Once, I found a thick layer of brake dust inside the brake drum, directly causing insufficient friction. When parking on a slope in such cases, always use wheel chocks—pulling the handbrake all the way might not help. I later developed the habit of shifting into P (Park) before pulling the handbrake. Regularly checking the handbrake travel is essential; it should typically lock after pulling up 6-7 clicks.

[LaKennedy]

The day before yesterday, while helping my neighbor check his car, I encountered this exact issue. He had just parked on a slope when the car started rolling back. The most likely causes are a loose or aged/rusted handbrake cable, making it feel particularly slack when pulled. If the brake pads have worn down to metal-on-metal, pulling the handbrake hard won’t help at all. Water getting into the rear drum brakes is also very common—parking on a slope right after washing the car is a surefire way to trigger this. One bizarre case I dealt with was after installing modified wheels without properly securing the brake discs, leaving the bolts loose. Key takeaway: Test the handbrake’s tension on flat ground; if the car still rolls when the handbrake is fully engaged, get it fixed immediately. As a temporary fix, you can shift into reverse or park to add resistance, but don’t rely on this long-term.

[HectorLee]

I reckon this issue should be analyzed from the mechanical structure perspective. The handbrake primarily relies on steel cables to pull the rear brake shoes against the brake drum for friction braking. If the cables become elongated or the fasteners loosen, pulling more will just result in empty travel. Excessive wear of brake shoes is the most common scenario - when the wear indicator metal piece starts making hissing sounds, that's your warning sign. The most dangerous situation occurs when moisture condenses on the brake drum forming a water film; never park on steep slopes immediately after washing your car. Over-polished brake drums actually reduce friction and require professional lathe work to restore a rough surface. Failed return springs prevent proper brake shoe retraction, essentially keeping the brakes partially engaged until complete failure occurs. Vehicles with modified suspension systems often experience mismatched handbrake cable lengths.