First the Fiero was stripped...
First the Fiero was stripped of all nonessential items, such as the running gear, rear suspension, rear brakes, body panels, interior, and bumpers. The frame was bolted to the table with metal jigs fabricated by Terry Fisher. The jigs kept the frame from moving as it was cut apart and welded. The adjustable legs on the table allow it to be precisely leveled to keep everything square. The frame was checked to make sure it was square. Note: This is also how racing cars are built.
The frame was cut, and the...
The frame was cut, and the back of the car was removed. New rear frame-rails were added at this point. The extended rails will be butt-welded togeth-er with a MIG welder and plated over with steel for strength. The cut (note arrows) was made before the frame starts tapering to simplify fabrication. Note that a level was used to make sure everything was square.
Temporary bracing was tack-welded...
Temporary bracing was tack-welded across the cockpit and doors to keep the pan square after the roof is removed. Once the roof is removed, the chassis will warp, and it will be very difficult to get it aligned again. The roof will be removed with a Sawzall.
The back half of the car was...
The back half of the car was re-moved. Beams were welded in the door frames to preserve rigidity. The doorjambs were cut off. The Fiero structure requires a lot of cutting to allow the Diablo shape to fit over it.
A new rear sub-frame was fabricated...
A new rear sub-frame was fabricated from 2x3-inch mild steel (0.120 wall). This subframe accepts stock Fiero suspension; up-rated parts may be substituted. The top mount picked up from the stock Fiero location. The subframe required many hours of fabrication and runs around the original firewall to increase the strength.
The extra crossmember ahead...
The extra crossmember ahead of the cradle adds strength to the lengthened chassis. Note how the cradle was reinforced.
A diagonal brace connects...
A diagonal brace connects the rear shock tower to the brace below the door area. These were tack-welded in place while everything was checked for alignment. The body subframe was fabricated to mount up to the body and be bonded in. It locates and strengthens the body. It was made to bolt on and off for maintenance or repair.
Posts were welded to the top...
Posts were welded to the top of the frame. The body subframe posts slip over these and were bolted in place. Once the top was removed, a lot of stiffness needed to be added. Here we see 2x3-inch bracing and framing that was added to strengthen the front of the cockpit area. These braces are not in the entry area of the body.
Always trial-fit any additional...
Always trial-fit any additional tubing with the body on before final welding.
While preparing the frame...
While preparing the frame for the D&R body, a lot of stock Fiero metal had to be removed. In order to clean it up and close the gaps, new metal was welded into the firewall area. You may need to do similar filling in other areas depending on which body you have.
11The A-arms had to be widened...
11The A-arms had to be widened 2 inches per side to match the track of the original car. Other kits may need more or less widening, and other alternatives use fully fabricated suspension arms or specially made offset wheels. This side view of the frame shows the extensive bracing added and the truncated frontend.
The front of the Fiero subframe...
The front of the Fiero subframe was trimmed back and capped for a professional appearance and more strength. The body was installed on the chassis and bonded to the top subframe with fiberglass. The subframe will be bolted to the chassis, and the body is bolted on with rubber isolators. The Northstar was installed in the rear cradle. Once the steps are complete, you wind up with a car such as the one in our lead photo.
When manufacturers in the kit car industry started cranking out Lamborghini and Ferrari replicas based on the Fiero platform, designers knew the chassis needed a stretch to achieve a more accurate look. The Fiero wheelbase is 93.4 inches, while a Lambo Countach is 96.5 inches, a Diablo is 104.3 inches, and a Ferrari Testarossa is 100.4 inches.
Although building on a standard-length Fiero chassis is much cheaper, many builders will not settle for the shortened look. There are many ways to lengthen the chassis, ranging from professional to suicidal, and weve seen em all.
The hardest part of the job is making sure everything gets lined up straight again when the car is complete. You will also usually need to widen the chassis or suspension to more closely match the track of the original.
Another problem is keeping the chassis square when the top is cut off (necessary with most Lambo kits). The standard Fiero relies on the top for much of its rigidity, so when the top is removed, the chassis will warp out of alignment if it is not firmly bolted to a rigid, steel chassis table. If you us the standard four-banger or 2.8L V-6, you might not notice misalignment as readily as you would with a fire-breathing turbo or a V-8 swap, but it will probably not track straight, and braking and tire wear could be adversely affected.
When we got a call from John Austin at Austin Conversions, we were excited to hear he was planning to stretch a Fiero 11 inches before installing one of his Design One Northstar swaps. Austin and partner Kevin Leslie have been making these installations for several years now, and they really turn the mild-mannered Fiero into a serious Corvette basher. Austin installed a D&R Diablo kit on an 84 base model Fiero for customer Phil Craine. He recruited Terry Fisher, who normally fills his time building NASCAR trucks and selling heavy-duty fasteners, to help with the fabrication.
Fisher has a professional chassis surface table in his spa-cious shop, just what was needed to keep the Fiero square while it was being dissected. A chassis table is constructed of thick steel to provide a perfectly level surface on which to attach a chassis so you can accurately measure and align all the components. It is also heavy enough to not be affected by changes in temperature or weather, which temporary wooden jigs can be. Working on an uneven shop floor or with flimsy wooden jigs is a recipe for chassis gremlins.
The Diablo kit is one of the most difficult to stretch, as a great deal of the original Fiero chassis must be cut away for body clearance, including quite a bit of the firewall. This means Austin and Fisher had to back-half the chassis and make an entirely new rear subframe from scratch. Some kits, such as Ferrari Testarossa and F355 replicas, do not require as much cutting and can be stretched more easily, requiring only lengthening of the chassis with extensions.
After all the stretch work, the resulting car will run like a thoroughbred and be better reinforced should the worst occur. Heres how this stretch was done.