Car Subframe

How to detect the car body frame faults

An independent assessment of the car body frame condition can only be cursory, by visual inspection. Noticeable damage, warping, cracks, corrosion, loosening of fasteners indicate the necessity for the frame repair or replacement. A more comprehensive inspection requires the use of special equipment and can only be performed at a service station.

You can see that the car body frame has to be examined by the following symptoms:

• correct wheel alignment is impossible;
• the doors close with difficulty;
• increased gaps between the body components;
• while driving, the vehicle pulls to one side;
• tires wear out prematurely or unevenly;
• creases have been formed on the vehicle floor;
• the stabilizer bushes are loose in the seats.

Causes of the car body frame failure

Cracks, breaks and warping of the car body frame are due to the intense force impact caused by a collision. Similar consequences occur due to entering of a wheel into a deep pothole, which is especially hazardous when driving at high speeds. Typically, the deformation of the axle beam, arms and subframe occurs at the same time.

In commercial vehicles, the frame skewing may result from the frequent transportation of excessively large loads or their improper distribution. The risk of damage to the part increases if the car is used in off-road conditions. Driving on poor-quality surfaced roads may cause loosening of rivet fasteners. The frame fracture may be caused by non-compliance with the towing rules.

A fairly frequent car body frame fault is corrosion. Most often it appears because of storing the car outdoors, as well as neglect and delayed elimination of minor damage to paint coating.

Repair of the car body frame

The frame repair can only be carried out in the conditions of a service station on a special frame machine. Special hydraulic pulling towers with a pulling capacity of 10 tons and higher, hydraulic rams and other types of equipment are used for its straightening. Preliminary calculation of forces to be applied and of the direction of pulling is performed with the help of special computer software.

Cracks in the frame are repaired by welding on of patches. In the case of too rusty areas the repair is performed using the same method.

If the corrosion extent is small, the damaged spots are cleaned, their surface is treated with a special solvent, then primed and painted.

Replacement of the car body frame

As a rule, first of all, all possibilities to eliminate the frame defects by repair are considered, as its replacement is very laborious and expensive, and in some countries it requires registration in the appropriate institutions. In the course of diagnostics, professional mechanics can determine whether a new frame installation is expedient. Usually, this kind of works is performed only in extreme cases, but if there is still a need for it, it should be made only at a service station.