As a rule, check the chassis is only when buying a used vehicle, while such diagnostics should be performed regularly.
Due to the fact that in operation the chassis of the car interacts with many related systems and mechanisms, to carry out its diagnosis is necessary in conjunction with the inspection of steering and braking systems.
Raising the vehicle with the lift, drove to the overpass, inspection pit or, in extreme cases, lifting Jack, should be carefully considered suspension parts for the presence on them of cracks, chips and traces of corrosion. Scuffs and small scratches – also a reason to worry as they silently testify to the assaults committed on the road obstacles, the consequence of which may be subtle deformation and damage nodes.
Inspect the shock absorbers, looking closely, there are no traces of leaking oil? At the same time ensure the integrity of their boots and bump stops. In peredneprivodnogo car be sure to check the integrity and tightness of covers of hinges of semiaxes and the presence of lubricant, squeezing their fingers.
Do not forget to check the condition of brake hoses, paying particular attention to the places of their attachment to the cylinders of the brake system. The anthers of the cylinders and the guides of the calipers are also subject to mandatory inspection.
If raising the car is not, the condition of the front struts can be estimated, alternately turning to the left and right front wheels.
Check backlash wheels and steering
The car with the front wheels suspended it is necessary to check the amount of free stroke without a steering response of the wheels. Gently swaying the handlebars from left to right, define the extreme positions of the steering wheel when the front wheels even start to change their position. In most models the value of the backlash should not exceed 50 or the distance of 15 mm on the outer arc of the steering wheel.
Then you need to check the backlash of the front wheels. Locking the wheel, try to rock the wheel, holding it first hands at the top and bottom, and then left and right. The presence of backlash of the wheel in the horizontal plane may indicate a malfunction in the steering system, if the wheel has noticeable play in the vertical plane, with the big share of probability it is possible to argue about worn out suspension components.
Don't forget that the play in the wheel can also be the result of wear to the wheel bearing. Checking the backlash of the wheels, at the same time, inspect the rims for dents and cracks.
Check the running gear in motion
Running the engine and starting the movement, need to let go of the wheel on a flat straight stretch of road. If the car starts to withdraw aside, this may be evidence of a violation of the suspension geometry, or, what is sadder — the body. The same picture is observed in the case of incorrectly adjusted the alignment of wheels or a significant difference in the air pressure in the tires.
If when braking the front of the car drops down significantly, and with vigorous acceleration sags the rear of the machine, should pay close attention to the shock absorbers, they are most likely worn out and not cope with its main task – to stabilize the position of the body. Staying and leaving the car, to slam on the wing and let him go. Serviceable shock-absorber "allows" the body to swing up, then down a bit and just a little bit up. After that, no wobble should not occur.
You know — a car with worn shock absorbers even on gentle bends will inevitably bias and stray from the path, hesitantly holding the road.
The presence of a crunch at the beginning of the movement with maximum displacement of the wheels will unmistakably indicate the need to replace the CV Joints proiznositsya order.
The final stage of test – driving on rough roads. Turning off the music and asking friends to keep quiet, listen carefully to the sounds that may make the front suspension when driving to the pits and potholes. More often knocks in the front of the car emit a worn bushing stabilizers and shock absorbers needs replacing or the hinges suspension.
Steering wheel vibration when driving on not the best road surface can be due to bent wheels.
Good luck to you! No nail, no wand!