Any hobbyist who's owned a Firebird of any generation is likely familiar with its unibody construction. The design incorporates a vehicle's sheetmetal panels and rear framerails, creating a single, stress-bearing body shell. An independent subframe containing the engine, front suspension and steering components is then bolted to the shell, yielding a complete vehicle that's typically lighter and more compact than one with a traditional frame.
A drawback to this type of construction is the lack of full-length framerails that connect the front and rear subframes. Because of this, a certain degree of lateral body flex is inevitable. It's typically felt as a loss of steering response during cornering maneuvers, or as passenger discomfort as the vehicle's body dampens road imperfections instead of the suspension. While the conditions are always present, it's usually more noticeable as a vehicle ages.
SLP Performance Parts in Toms River, New Jersey, has developed some of the best-fitting bolt-on subframe connectors for Fourth-Gen Firebirds (PN 70801). Retailing for $380, the units come powdercoated black. Those for our '01 Trans Am were on our doorstep within a few days of placing the order.
The aftermarket industry created a solution many years ago, and myriad companies presently produce subframe connectors for virtually any Firebird on the road today. These subframe connectors stiffen the vehicle's structure, which can improve handling with the stock suspension, but they also provide a great foundation for further corner-carving upgrades that would normally exacerbate the stock chassis' flex issues.
The Major Types
There are two common varieties of subframe connectors-weld-in and bolt-on. The weld-in type offers maximum benefit, as its design solidly links the front and rear framerails together. Installation, however, is fairly permanent, and cutting or grinding on the framerails, floor pan, and/or connectors is required if the units must be removed for any reason.
Bolt-on subframe connectors are far less permanent. A pair can typically be installed without significant modification to a vehicle's framerails or floorpan. Well-designed units fit snugly, while reducing body flex and improving ride quality.
Installation
Knowing the positive effects that subframe connectors can have, we decided a set was in our '01 Trans Am's future. Since our low-mile Firebird is unmodified, we were reluctant to install any connector that was permanent, which made high-quality bolt-on units our only choice.
Though many companies may offer similar products, we're very familiar with those from SLP Performance Parts. The ease of installation and positive benefits made them the most logical choice for our application.
We ordered a pair of coupe-specific Fourth-Gen bolt-in subframe connectors (PN 70801), and a large box containing the necessary components and installation hardware arrived on our doorstep within a few days. The supplied instructions estimate that installation should take an average hobbyist around two hours to complete, and suggests the use of a hydraulic lift for easiest completion. Follow along as we install a pair of bolt-on subframe connectors onto our Fourth-Gen Firebird, and noticeably improve its structural rigidity and ride qualities.