Before starting measurements on the stand, it is necessary to clean the body floor and the power unit. Measurements are performed using special devices after installing the car on the stand lift and removing the wheels.
The following are subject to control:
- doorways;
- upper mounting points of the front suspension struts on the wheel housing;
- front and rear wheel alignment angles;
- steering gear housing installation height.
The height and correct installation of the steering gear housing determine the directional stability of the vehicle during acceleration, braking and driving on roads with uneven surfaces.
After carrying out inspection and repair work on the slipway, the following must be done:
- replace the ball joints of the front suspension arms and steering rods, and if necessary, the steering mechanism;
- check the condition of the brake system, steering, wheel rims, tires and suspension components;
- check and, if necessary, adjust the alignment angles of the front and rear wheels.
The geometric dimensions of the car body frame and the points between which measurements should be taken are specified in the design documentation of the Renault company. Special sets of devices and computer-based documentation have been developed for various testing and repair-restoration stands and rigs, simplifying the execution of repair work.
Do not replace welded structural elements until the absence of deformation of the vehicle body floor has been confirmed.
It is usually difficult to detect minor body deformations caused by medium-force impacts to the front or rear of the car. If in doubt, check suspicious areas organoleptically - by feeling the body surface with your fingers. Remove any defects you notice by straightening and straightening.
If necessary, complete removal of welded body parts is performed at the welding points, partial removal is performed by cutting out the deformed section. Installation of a new element is performed by welding, taking into account an allowance of approximately 20 mm.
Removal of contact welding points when removing damaged or deformed parts, the original shape of which cannot be restored by straightening directly on the vehicle, is carried out using a pneumatic chisel or by drilling them out with a carbide tool with a centering protrusion.
It is necessary to cut the metal from the contact welding points from the periphery to the center. In case of serious damage to the body's attachments (hood, fenders, etc.) it is recommended to replace them, since restoration is often impractical, especially when parts can be purchased not only in auto parts stores, but also at dismantlers, which allows you to significantly reduce repair costs.
Features of welding works during body repair
To avoid damage to electrical equipment during welding, it is necessary to disconnect both terminals of the battery from the vehicle's electrical system; it is advisable to remove the battery from the vehicle.
Before disconnecting the battery, you should check the code combination of the car radio, since it can only be restored at the manufacturer's factory. The contents of the memory devices of other electronic devices in the car may also be lost, so you need to remove the ECU from the car.
Use only spot welding methods. In cases where this is not possible, gas-shielded arc welding may be used as an exception.
Welding of galvanized parts must be carried out under conditions of supply ventilation, since zinc oxide vapors released during welding are toxic. In addition, it is necessary to take into account the technological requirements associated with the specific features of welding galvanized parts (increase in welding current by 10–30%, use of heat-resistant – up to 400°C – electrodes made of solid copper, stripping of electrodes until a reliable contact spot with a diameter of 4 mm is formed, increase in welding time).
Welding or soldering of refrigerant-filled air conditioning system components is prohibited.
Straightening tool
There are currently a large number of straightening hammers on sale, which differ significantly in weight, striker shape and material. The working part of straightening hammers is processed along the radius and must be polished. Traces of nicks, scratches, marks or other damage on the striker of straightening hammers are not allowed.
It is not recommended to use hammers with flat striking parts when straightening the front surfaces of body panels, as they leave marks in the form of nicks on the metal.
Wooden hammers (mallets) are used to straighten heavily deformed parts. On small deformed areas, straightening is carried out with a special hammer with a notch on the striker.
(Source is located on the website: «Renaultbook.ru»)
Light hammers and "smoothing" hammers are used to remove small dents and nicks when the surface is being prepared for painting or when it is necessary to restore the surface without damaging the paintwork.
Hammers with plastic or rubber heads are used for final (fine) straightening of painted surfaces.
Shaped plates, mandrels and anvils are designed to support thin sheet metal body panels during the process of restoring deformed areas.
The working surfaces of these tools should always be well polished. To eliminate small dents or bulges without damaging the paint, the surfaces of some tools are brought to perfect cleanliness and chromed.