What is the function of the two small holes on the brake discs of the Tiggo 3?
4 Answers
The two small holes on the brake discs of the Tiggo 3 serve the following purposes: 1. Heat dissipation; 2. Reducing brake noise; 3. Weight reduction. However, more holes on the brake disc are not necessarily better. Drilling holes on the friction surface can weaken the brake disc to some extent—the more holes, the weaker the disc. The holes and the friction surface form a right-angle "cutting edge." When the brake pads are pressed tightly against the disc by hydraulic pressure and slide over the small holes at high speed, they are repeatedly scraped by these "cutting edges." The more holes there are, the stronger the cutting effect. The Tiggo 3 is a compact SUV launched by Chery Automobile. It measures 4420mm in length, 1760mm in width, and 1670mm in height, with a wheelbase of 2510mm. It is equipped with either a 1.5L or 1.6L naturally aspirated engine, delivering maximum power outputs of 85kW and 93kW, respectively. The vehicle is paired with a CVT (simulating 7 gears) or a 5-speed manual transmission.
After all these years of repairing cars, I've found that the two symmetrical small holes on the Tiggo 3 brake discs mainly serve as installation positioning references. When mounting new brake discs onto the wheel hub, these holes perfectly align with the locating pins, ensuring precise disc positioning. If misaligned, it causes brake shudder and uneven wear. These holes also slightly reduce weight – not much, but it helps with steering responsiveness. Sometimes after car washes, you can see water draining from them, though their primary function remains installation accuracy. Remember to use specialized tools inserted into these holes for disc replacement – far more reliable than going by feel.
I once replaced the brake discs on my Tiggo 3 myself and was initially puzzled about the purpose of those two small holes. Later, I realized that when installing new discs, the holes on the disc must align with the protrusions on the wheel hub; otherwise, the disc would tilt after tightening the screws. It's like the snap-fit of building blocks, ensuring precise repositioning after each disassembly. Additionally, the small holes reduce metal weight, making the steering noticeably lighter. Once after driving in the rain, I touched the brake discs and noticed no water accumulation around the holes, suggesting they also aid in drainage and rust prevention. While not as effective in heat dissipation as vented discs, the design is quite ingenious.
From an automotive engineering perspective, those two approximately 6mm diameter holes primarily serve as manufacturing datum points. The stamping production line uses locating pins inserted through these holes to secure the blank, ensuring machining accuracy. Secondly, they reduce weight by around 150 grams, lowering rotational inertia to make suspension response more agile. While primary heat dissipation relies on internal air channels, the holes increase heat dissipation surface area by 0.5%. The material selection of high-carbon cast iron intentionally thickened the hole edges by 1mm to prevent stress cracking. This design maintains 380°C heat resistance while balancing installation convenience and dynamic performance.
