There are two minor modifications...
There are two minor modifications necessary on the knuckle. The steering stop tab under the steering arm must be removed. The Fiero knuckle was originally a front-wheel-drive part. The steering arm then must be drilled to accept a 5/8-inch bolt. Refer to the picture and, using a hacksaw or other suitable tool, remove the steering stop tab. You may wish to deburr and paint the freshly exposed metal.
With the bracket attached...
With the bracket attached to the knuckle via the 9/16-inch bolt (not fully tightened at this time), the original ball-pin pinch bolt can now be reinstalled. Note that there will be some interference between the pinch bolt and the 9/16-inch bolt. Lightly tap the pinch bolt into position with its head toward the front of the vehicle and install the original locking nut snugly. Use the 5/8-inch hole in the round boss as a guide to drill the taper out of the factory steering arm. The arm can easily be drilled with a handheld electric drill. After drilling is complete, install a flat washer on the 5/8-inch bolt provided and install the bolt through the boss and steering arm from the bottom; secure it with a second flat washer and locknut at the top. Tighten (in this sequence) the 9/16-inch bolt to 40 lb-ft, the pinch bolt to 25 lb-ft, and the 5/8-inch bolt to 140 lb-ft.
In order to install the 9/16-inch...
In order to install the 9/16-inch bolt through the knuckle in place of the original lower ball joint, it will be necessary to remove the axle. With the lower control arm removed, loosen the axle nut and slip the axle out of the hub. Make sure the lower surface of the knuckle is clean and flat as it will mate with the knuckle adapter bracket. Slip the 9/16-inch bolt through the ball-pin mount hole in the knuckle from the top side and engage the knuckle adapter bracket over the end of the bolt. Before installation of the washer and nut, be sure the round mount boss of the bracket aligns with the hole in the steering arm of the knuckle. There is potential for the rectangular block section of the bracket to hit the knuckle and cause misalignment of the steering-arm hole. If there is interference, the knuckle must be ground or sanded to increase clearance in the area of interference. The tapered hole in the steering arm needs to align with the hole in the round boss of the bracket.
Each control-arm pivot comprises...
Each control-arm pivot comprises two urethane bushings and a steel sleeve. The bushings should be installed from each end of the housing so that one urethane flange faces forward and one faces the rear of the vehicle. With the bushings installed, the steel sleeves can be inserted into their centers so that the ends of the sleeves are flush with the surfaces of the bushing flanges.
The 3/4-inch spherical rod...
The 3/4-inch spherical rod end screws into the threaded opening at the end of the main tube of the control arm. This is the opposite end from the bushing housing. Before installation of the rod end, it must be sleeved down to 1/2-inch ID in order to properly fit the 1/2-inch hardware supplied. Press the rod-end spacer sleeve into the rod end using a bench vise or hydraulic press. Install the 3/4-inch jam nut onto the stud of the rod end and screw the rod end into the control arm. When properly installed, the center of the rod end should be 12 inches from the center of the urethane bushing.
Tighten the jam nut to secure...
Tighten the jam nut to secure the adjustment, being sure the axis of the spherical bearing is parallel with the axis of the urethane bushing. Do not use a lever through the ball as a means of holding the adjustment while tightening the jam nut, as this could result in damage to the rod-end housing.
The control arm is now ready...
The control arm is now ready for installation into the chassis in place of the original arm.
The new control arm should...
The new control arm should be oriented so that the main tube (1-1/4-inch diameter) of the control arm is toward the rear of the vehicle and the toe-link mount tab is up. Attach the arm using the original hardware.
The toe link comprises six...
The toe link comprises six main components; a 5/8-inch lefthand spherical rod end, a 5/8-inch OD x 1/2-inch ID rod-end spacer sleeve, a 5/8-inch righthand clevis, a left- and righthand threaded toe-link tube, and 5/8-inch left- and righthand jam nuts. Before installation of the rod end, it must be sleeved down to 1/2-inch ID in order to properly fit the 1/2-inch hardware supplied. Press the rod-end spacer sleeve into the rod end using a bench vise or hydraulic press. Install the jam nuts onto the rod end and clevis studs. Screw the clevis and rod end into the appropriate ends of the toe-link tube and adjust them so that there is an equal amount of thread protruding from each end of the tube. Initially (for standard-track-width vehicles), there should be approximately 1/4 inch of thread protruding past the jam nut on each end to achieve close-to-correct toe settings. Install the clevis to the mounting tab on the leading tube of the control arm. Note that the mounting tab is slightly narrower than the slot in the clevis. The clevis should be installed with a 3/8-inch SAE washer on either side of the tab for a tight fit. With the washers in place, insert the 3/8-inch bolt with flat washer and locknut. You are now ready to attach the control arm to the knuckle adapter bracket. If the knuckle was removed for modification, now is the time to reinstall it to the strut.
Place a 1/2-inch USS flat...
Place a 1/2-inch USS flat washer (USS has a large OD compared to SAE) over a 1/2x2-inch hex bolt and pass the bolt through the 3/4-inch rod end. Slip a 1/2-inch SAE washer onto the bolt, apply thread-lock compound, and engage the rear end of the knuckle adapter bracket. Tighten the bolt to 80 lb-ft.The spherical bearing end of the link mounts to the vacant threaded hole on the front end of the knuckle adapter bracket. Again, using a 1/2x2-inch bolt and two 1/2-inch SAE flat washers, sandwich the 5/8-inch rod end to the front of the knuckle adapter bracket. Be sure to apply thread-lock compound to the bolt and tighten to 80 lb-ft. This outlines the installation of one side and should be repeated for the remaining side. When complete, the wheel alignment should be set before driving the vehicle.
The rear suspension on 84-87 Fieros is not ideala condition called bumpsteer is to blame. Bumpsteer is a change in the toe setting (alignment) as the wheels move up and down. This condition is responsible for the twitchy handling you may have experienced during transition from a straight line into a corner, and it can be the reason for most high-speed instability problems. Zero bumpsteer is ideal.
In most cases, it is possible to improve the bump characteristics of a vehicle by moving the locations of the steering linkage pivot points and/or changing the lengths of the tie rods. The Fiero is essentially a mid-engine car with a front-wheel-drive unit mounted mid-ship. The steering knuckles from the front-drive vehicle are retained and are tied off to the frame (engine cradle) to eliminate the steering. Unfortunately, the steer effect is not fully eliminated and we are left with bumpsteer. Furthermore, modifying the tie rod mounting points and/or lengths will only help the situation within a certain range of the suspension travel, creating what might be called a sweet spot.
Most enthusiasts know that lowering the center of gravity by lowering their car will greatly improve handling. Many factors affect just how low is practical. Will you use the car primarily for racing, where performance is everything, tracks are as smooth as glass, and ground clearance need only be a couple of inches? Perhaps you want a certain stance where lowering the vehicle 1 inch or 1-½ inches is all thats required. Are you building a kit car that requires a 3-inch drop just to make it look normal? As you can see, lowering a car means different things to different people.
In designing a bumpsteer fix, Held Motorsports thought it pointless to design a single sweet-spot bumpsteer fix when everyones sweet spot is in a different location. Its solution was to make changes to the geometry that totally eliminate bumpsteer through the entire range of suspension movement, making it universally applicable.
The Held Bump Stop Kit ($625) includes two control arms, two toe links, and two knuckle adapter brackets. The control arms come with urethane pivot bushings, sleeves, and weatherproof spherical bearings at the knuckle assembly. The kit allows the use of stock struts, and while the kit doesnt require any frame modifications, welding, or other heavy mods to the car, the knuckle assembly does require some minor modifications (one hacksaw cut of 1-½-inch length). The steering arm taper is also drilled out using the fixture provided in the kit.
Using the Bump Stop kit allows installation of most aftermarket add-on sway bars, and its available in a wide-track version. The kit does not change the offset of the tires, either. Helds kit also works in conjunction with its other suspension components (such as 13-inch brakes) and performance front-end suspension components to noticeably improve the ride of a Fiero.
Initial preparation for the installation involves removing and discarding the factory rear control arms and tie rod assemblies. It may not be necessary to remove the knuckle assembly from the strut in order to perform the conversion, but one may find it easier to work on the knuckle when it is off of the vehicle.