When the body is deformed, its geometry is violated. Due to the incorrect geometry of the body, there are irregularities in the arrangement of the wheels, violation of the diagonals, door openings, glass frames. Deformations form folds on the floor, base elements, and on the frame. Especially large folds are formed in the impact zone. Other folds can be found in long body parts and in large gaps between welds.
It is necessary
Specialized caliper, scale bar, tape measure. If available, a template stand or an electronic measuring system
Instructions
Step 1
Signs of a violation of the geometry of the body can be detected already during a preliminary inspection: crumpled body parts, visible changes in the base (control) points. The preliminary inspection itself is carried out with the car raised on the lift. The base of the body or frame is visually inspected and palpated by hand to detect characteristic folds. In this case, natural folds at the bending points of the stamped parts are not taken into account. The presence of deformation folds indicates a certain violation of the geometry of the body. Folds can be faint or pronounced and located in places that do not affect the main dimensions.
Step 2
If no folds are found, check the correct installation of the wheels. This control can be carried out quickly and with high accuracy on an electronic test bench. After checking the camber / toe-in of the front axle, the geometry of the position of the rear axle and the installation of the wheels are checked. In this case, you should compare the position of the wheels on different sides of the car. If the position of the right wheel differs from the position of the left, there is a violation of the geometry of the body. In the absence of an electronic stand, the procedure is carried out using a specialized caliper.
Step 3
Measurement of the diagonals (control points) without dismantling the mechanical assemblies should be carried out according to the manufacturer's instructions, according to which the control diagonals are drawn between the control points. These diagonals are drawn between the frame guide holes and from them to the points of the mechanical assemblies (fixing bolts) or hinges. The symmetry of the diagonals is compared. The distance between points on one side and symmetrically on the other side is determined. The dimensions must be the same. A difference in these measurements indicates a violation of the geometry of the body. The procedure for measuring the diagonals is carried out with a car installed on a lift or on a pit using a scale bar.
Step 4
The scale bar check starts at the center of the base of the body or frame. In this part, geometry is rarely violated and it is convenient to use it as a reference point for other diagonals. The position of the crossheads is determined, the distances from the central hole under the body axis to the control points specified by the manufacturer are carried out and measured. Diagonals are measured between points on the frame (base of the body) and points on the front or rear axle. For some inspections, you will have to partially remove certain components.
Step 5
In the absence of a scale bar, control with a lower degree of accuracy can be performed using a tape measure.
Step 6
It should be noted that on some foreign cars the distance between the axles of the wheels is located asymmetrically to the axis of the body. Often the axis of symmetry of the rear wheels can be offset relative to the axis of the body. In this case, the factory instructions must indicate the specified distance between the axles separately for each side.
Step 7
When checking the body geometry, a template system (stand) with seats for base points can be applied. When using this system, the body is set on a template, and any violation of the geometry is immediately fixed. When replacing large parts and structural elements of the body, this stand becomes a slipway.
Step 8
When checking the body geometry with an electronic measuring system, the coordinates of the reference points are determined by a probe or a laser beam. The computer compares the measured data with the manufacturer's specification. The same system checks the wheel alignment angles.
