14.4 Major Repair Techniques

In major repair work the method of repair is to analyse the crash, establish the order in which the collision damage occurred, and reverse the order when correcting the damage. Distortion of the vehicle's underframe in the case of mono constructed vehicles, or of the chassis in composite constructed vehicles, must be rectified first before any other part of the repair is attempted. Any vehicle body under major repair will never hold its correct alignment unless underframe damage has been completely repaired first. This essential stage in the repair of the vehicle is carried out by first inspecting the damage and checking its alignment by one of the recognized methods to locate the exact position and extent of the damage.

Correction is carried out by using alignment and repair equipment in conjunction with hydraulic pulling and pushing equipment to realign any underframe members which do not align with the specified locating points (see Figure 14.78). Any members which are beyond economical repair can be cut out and replaced with new sections by using a combination of power tools and MIG welding equipment. The use of this hydraulic equipment together with the alignment and repair system will ensure precise accuracy of the complete underbody.

Figure 14.78: Pulling equipment being used to realign underframe members ( Car-O-Liner (UK) Ltd)

The next stage of the repair is the realigning and reshaping of the body shell structure, and is normally known as roughing out the damage. After alignment checks...