Buick Turbo Framerail Modification - Power Trip

The ring-and-pinion are oftentimes overlooked during a buildup; they're not exactly sexy power parts. However, choosing the right gear (along with a capable installer) is critical to getting reliable performance on the strip, and peace and quiet on the street. I contacted Reider Racing and explained my goals, and its helpful staff shipped out a Precision Gear ring-and-pinion with a 3.42 ratio, same as stock. For you non-Buick nuts, in all but the fastest cars, the factory ratio doesn't need to be fiddled with like in other performance applications.

The GN/T-Type/Turbo-T/GNX was blessed with a beefy, 8.5-inch 10-bolt from the factory, and I'll be maximizing its strength with a TA Performance diff cover.

This cover strengthens the rear by adding support to the bearing caps by way of two load bolts that push against them. The CNC-ed TA covers are made of 356 aircraft-grade aluminum, heat-treated, and stress-relieved, and feature fill and drain ports and an increased capacity over stock covers.

When I told Jack Cotton that I wanted this street car's rear end to be ready for the strip, he recommended the HRPartsNStuff rear bar. "It's good on the street, you don't have to weld it in, and it absolutely keeps these Buicks from twisting under a hard launch," Jack stated. This thing measures a whopping 1.25 inches thick, and comes with high-end hardware and everything needed for installation, including thorough instructions. The one-year guarantee is the frosting on the cake.

As previously mentioned, the right rear gear installer can make the difference between a whining gearset that makes you want to throw yourself into traffic, and a correctly installed set that will give you thousands of quiet, problem-free miles. Cotton's Performance Center contracts with a local shop that sets up gears so perfectly, I'm told they're quieter than a mouse fart in church. The down side? This guy is so busy with word-of-mouth that he won't let my camera into his shop to cover the install! Brian Cotton will need access to the framerails anyway, so the 10-bolt is unbolted and dropped down.

With the rear down and shipped to the gear shop, Brian has room to work. He breaks out the tape measure: the distance between the outsides of the stock framerails is 46.5 inches.

Cotton's will be cutting my rails to fit fat slicks at the track, and huge rims and tires on the street. But before the rails can be cut, the inside of each framerail must be reinforced, as cutting them removes much of the structural rigidity.

Brian first removes the GNX suspension's panhard/stiffhard brackets to gain access to the rails. I converted back to a 4-link setup after testing the GNX rear, but the brackets were left on until now. Next, he will be creating four support brackets for each side, to prevent the rails from bending. Here he cuts steel pieces for a bracket with a plasma cutter.

A wheel is used to remove the rust and create a weldable surface.