Corner Carving The Bird

We figured the 17-inch Edelbrock 409s would have filled up the wheelwells, but the stock nosebleed ride height made for lame-looking gaps between the tires and fenders. We had to drop it.

For once, we were spared the wrenching! As soon as we cruised in to Edelbrock’s installation facility, Karl Stuber got right to work. After removing the end links from the stabilizer bar, he unbolted the two brackets securing the brake flex line—one mounted on the spindle and the other on the frame.

Two bolts attach each strut to the spindle; removing those allows removal of the coil springs. The car was lowered to the ground, and we raised the lower A-arm with a floor jack to compress the spring before unbolting the strut from the spindle. Alternatively, you can use a spring compressor to restrain the spring. Either way, be careful.

Slowly lower the floor jack to gradually release the spring’s energy. The spring should pop out of the lower A-arm pocket, or you may have to gently pry it out of the lower spring pocket. (If you used a spring compressor, the spring will be short enough that it should drop right out.)

Remove the upper strut mount, drop the strut out through the wheelwell, and here’s what greets you. It’s a steel bearing cushioned by a large rubber biscuit. Stuber made sure each bearing spun freely without binding. Seized bearings prevent the shafts from turning with the wheels and may trash ’em in a hurry.

The stock springs hardly made for a corner-carver stance, so Edelbrock chose an Eibach custom-rate lowering spring kit (PN 5231) to drop the car to a more tasteful ride height. The factory anti-squeak spring cushions were in good shape, so we reused them. Tape ’em to the top of the springs to keep the pads from falling out during installation.

Tokico’s five-position adjustable struts and shocks are conveniently adjustable from the top with a flat-blade screwdriver. The adjustment mechanism is relatively fragile, so be sure to follow Tokico’s specified torque specs when you install them. Stuber bolted the upper strut mount in place and torqued the nut.

The new Eibach springs were just a bit too long to fit in the spring pocket uncompressed, so Stuber subjected ’em to a few turns of the spring compressor. To ensure proper ride height, make sure the end of the lower coil is located between the two drilled holes at the inside of the spring pocket. Raise the lower A-arm with the floor jack and bolt the strut to the spindle. Reattach the flex line brackets, reinstall the stabilizer-bar end links, and you’re good to go.

The third-gen F-body has a three-link rear suspension that consists of two lower control arms, a Panhard bar, and a torque arm. The basic design isn’t bad, but the strength of the structural members leaves something to be desired. Check out the difference between the stock C-channel lower control arm and the stout Edelbrock replacement that’s fully boxed and outfitted with polyurethane bushings. No comparison. Stuber supported the rearend, and removed and replaced each lower control arm, one at a time, to keep the axle oriented correctly.

The Panhard bar was next in line for replacement. The driver-side end mounts to the frame, and the other end mounts to the axle. Its purpose is to locate the rearend laterally, so it’s got to be rigid enough to withstand high-g cornering. We’re not really sure what happened to the stock bar, but we know the nasty bend wasn’t a factory option. Maybe we should have bought a Carfax report for this thing before we dragged it home. Anyway, this certainly is a good case for installing the beefier Edelbrock Panhard bar.

On to the torque arm. This was the most time-consuming part of the rear suspension work. At the rear, the torque arm is bolted to the differential case, and the front is constrained with a rubber bushing that’s attached to the transmission tailshaft. Well, you can imagine what kind of shape the bushing was in, considering our trans mount had been broken since our last dragstrip flogging, allowing the torque arm tons more movement than it should have. The rear of the torque arm was unbolted from the differential case, allowing the arm to drop out from under the car.

Side by side, it’s easy to see the thicker-gauge steel and more robust design of the Edelbrock torque arm. This translates to less deflection under high-torque loading, which preserves rear suspension geometry and proper pinion angle.

Before installing the torque arm, Stuber opted to replace its front bushing with a tougher polyurethane biscuit. This required removing the rivets that hold the factory rubber bushing to the steel mount. Don’t be stupid—wear eye protection!

The Car Craft curse strikes again. Edelbrock’s torque arm was engineered for third-gens built with the common 10-bolt rear, but our Formula was fitted with the relatively scarce 9-bolt Australian diff. We had to remove part of a rib on the differential case to allow E’s torque arm to bolt up.

The stiffer polyurethane bushing was a little tricky to compress enough to bolt the steel shells back together. Stuber used a large-jaw vise-grip to squeeze the shells together, allowing him to bolt down the whole works.

Yikes! We’d removed the crossmember for better working clearance, and good thing we did! There were two pretty severe cracks near the mounting slot, probably from the hammering action of the broken transmission mount. Fortunately, one of Edelbrock’s master welders was able to repair it for us.

The rear shocks are an easy swap on these cars. Support the rear axle and unbolt the lower shock mounts from the axletubes. You can access the upper shock mounts by folding down the rear seat and pulling up the carpet. Remove the contoured foam pad and you’re there. Unbolt the upper mount and the shock drops out from under the car—literally—so you might want to have a buddy under the car to hold it.

Stuber slid each Tokico shock through the floor, tightened the nut until the rubber bushing was slightly compressed, and installed the jam nut to lock it in place. Adjusting the shocks is as easy as pulling back the carpet and spinning the dial.

The stock rear springs should drop right out, provided the shocks are unbolted from the axle. The rear springs in the Edelbrock kit are high-performance Eibach variable-rate coils designed for a slight drop in ride height. Simply lift ’em in place, raise the rearend, and bolt the lower shock mounts to the axletubes. You’re done. But don’t forget to install the zerk fittings and grease the bushings.

Installing the strut tower brace requires some careful measuring, since it doesn’t bolt to any factory mounting points (all mounting holes must be drilled). Stuber bolted together the entire three-piece strut tower assembly, attached its brackets, laid it over the engine bay, and measured to make sure it was centered. Note that the engine isn’t centered in the engine compartment, so don’t use the plenum as a reference. Once the bar was centered, Stuber drilled two holes for each strut tower bracket, and two holes in the cowl to attach the braces. The car was lowered to the ground to pre-load the chassis, and we made sure none of the bracing was touching the hood before torquing the entire assembly to spec.

Edelbrock just introduced these trick machined tie-rod sleeves. Although they’re not likely to directly impact performance, the machined flats definitely make adjusting the toe setting easier and more precise. And they’re a heck of a lot more durable than the cheesy rolled-steel stockers. Stuber measured the length of each tie-rod assembly to get the toe setting in the ballpark and tightened the jam nuts against the sleeve, but an alignment is in order after this much suspension work.

The end result wasn’t only better, more predicable handling; we also rid ourselves of the embarrassing four-by stance. The car dropped 1.2 inches and 0.75 inch, front and rear. Edelbrock claims these springs should drop 1.60/1.30 inches front/rear, so we expect everything to settle a bit more with some hard drivin’. We’re elated that the car finally looks like it deserves those bad-boy 17-inch wheels, and it’s even more thrilling to have a chassis that makes the most of the killer rolling stock.

One of the advantages of building a third-gen GM F-body is having a pretty stout chassis to start with. When they were new, the Z28 and WS6 cars were among some of the best-handling machines ever to grace the performance car market. Despite having been used and abused, our ’88 Firebird still drove surprisingly decent after we rescued it from the previous owner and bolted on a set of Edelbrock wheels with Yokohama treads to replace the ancient dry-rotted rolling stock. But that’s not to say there wasn’t room for improvement.

The 80,000 hard miles had taken their toll on the struts and shocks, so the damping wasn’t quite adequate at higher speeds, causing the car to bounce a few times after hitting a bump on the freeway. That not-so-safe feeling was compounded by a persistent thunk sound coming from somewhere under the car. And the stock four-wheeler ride height wasn’t doing anything for our image. We felt it was due time to go through the chassis, but you expect more than a stock rebuild from Car Craft, right?

We headed out to the Edelbrock empire in Torrance, California, to get the ’Bird outfitted with all the third-gen goodies offered by big E. Tokico supplied us with its excellent five-position adjustable struts and shocks, which should help us dial in the car if we ever get around to autocrossing it. Now the car’s a blast to drive at any speed, and strangely enough, the new suspension is more compliant, even with the shocks and struts set on full firm. Follow along and see how it was done.