When choosing a second-hand car, checking the frame is one of the good ways to judge whether there is a collision accident, because most of the car frames that have had accidents will leave traces, depending on whether you can distinguish them.
Most cars adopt "one-piece body" structure, and the impact deformation of the frame will produce some adverse reactions, which can be judged by trial operation. For example, the steering is unstable; There is noise of wheels in the process of going straight; Tire has eccentric wear marks; Deviation during braking, etc. At rest, it can be checked by the following methods: check whether the front and rear wheels on the left and right sides are in a straight line respectively, otherwise the whole frame is bent; The clearance between the rear side of each wheel and the wheel cover should be approximately the same, otherwise the frame or the whole body will show signs of bending; Check whether the gap between the hood and the fender, the joint between the door and the fender, and the gap between the door and the door are symmetrical, otherwise it is likely that the hood and the door have been replaced, which is of course related to the accident.
Open the hood and check whether there are any traces of welding or cracking on the two longitudinal beams running through the engine compartment. If it is an accident of rear-end collision or side impact, the frame will be squeezed, bent or cracked, and welding is needed for maintenance. If possible, you can obviously check the lifting frame, because most car chassis have stiffeners, and you can judge the condition of the car by checking whether the stiffeners are straight or not. Car secretary used car experts remind consumers: in the process of selecting used cars, the frame is a very important inspection part, so don't take it lightly.
Used car inspection project
The first pair of numbers: the engine and body numbers must match the information in the driving book, otherwise it is not only illegal, but also unable to get compensation from the insurance company in the event of an accident.
Check the braking for the second time: try to brake at different speeds to ensure that there is no side slip. If equipped with ABS system, you can try to brake suddenly at a speed above 30km/h to test whether ABS works normally. If ABS works normally, you can feel the jumping feeling from the foot brake.
Third, look at the body: the connection between the door, headlights and taillights is smooth and there is no interface. The fender color of all parts of the car body should be uniform, and there should be no bumps or waves when looking forward from the rear fender. It is recommended to try magnets in all parts of the car body. If it is unattractive, it may be the result of excessive dust removal. But when it comes to aluminum or carbon fiber fuselage, this trick doesn't work.
The fourth engine inspection: first, look at the appearance of the engine for damage or oil leakage, and see if there are signs of damage to parts and whether the spark plug leaks electricity. To test whether the engine can start smoothly, it is best to test it when the car is cold, and the result is more accurate. Pay attention to whether there is oil suffocation when driving and whether the static speed is normal. Check whether the response of the engine system is fast enough, whether the horsepower of the front of the car is sufficient, you can step on the accelerator and let it go immediately, and then observe the speed of the increase of revolutions, and whether the revolutions increase rapidly when stepping on the accelerator. In addition, whether the car can run smoothly after refueling and whether there is noise also needs to be checked. Check the engine for abnormal smell after driving, and check the engine for oil leakage many times.
Fifth suspension measurement: press the four corners of the car body to observe whether the suspension reaction force is uniform, and pay attention to the abnormal sound when pressing the car body. However, you must ask the owner for such a big move, and be careful not to deflate the car when pressing. A better way is to drive the car to the garage, raise the car and see if there is any oil leakage or slack in the suspension system.
Sixth try gearbox and clutch: try to change different gears to ensure that all gears can operate normally. The fault of manual gearbox is usually that it can't smoothly enter a certain gear or can't engage. Check the third gear and the fourth gear during the test run, or accelerate on the uphill road. If the engine speed continues to increase, the clutch may wear out and need to be replaced.