General Body Construction (Unibody) Description. Chevrolet PJJ 2000

For 1990-2009 cars

This information pertains to unitized body construction. The engine and transaxle, front suspension control arms, and rack and pinion steering are supported by the engine frame which is bolted to the vehicle at six locations. Each mounting location is cushioned by a thick rubber insulator. These insulators are specifically designed for each location to give the proper amount of structural strength while providing maximum road noise isolation. Different insulators are used at the various frame-to-body attaching points to change ride and handling characteristics of the vehicle.

Mounting provisions for the front suspension system are also shared by the body components through the suspension strut towers. The towers must be dimensionally correct in relation to the underbody to maintain proper suspension geometry.

With unitized body construction, underbody components must be properly aligned to assure correct suspension location. In case of collision damage, it is important that the body dimensions be checked thoroughly, and if necessary, realigned in order to accurately establish proper dimensions.

Since the individual underbody components also contribute directly to the overall strength of the body, it is essential that the proper welding techniques be observed during service repair operations. The underbody components should be properly sealed and rustproofed whenever body repair operations destroy or damage the original sealing and rustproofing. When rustproofing critical underbody components, it is essential to use a quality air dry primer such as corrosion-resistant chromate or equivalent material. Combination type primer-surfacers are not recommended.