- Building the "Screaming Chicken" in 1/8^th scale

The Pontiac Firebird first came around in 1967 and was available in five main variants: the base Firebird, the Firebird Sprint, the Firebird 326, the Firebird HO (High Output), and the beastly Firebird 400 (with a 325hp 400cui V8).

Pontiac marked the Firebird line as "The Magnificent Five" and all variants could be ordered either as a hardtop coupe or as a convertible.

These cars marked the first generation of the Firebird and production continued through 1969, at which year the Trans Am was introduced (at first as a performance option for the Firebird 400).

In 1970 the second generation Firebird was born, sporting a complete redesign that turned it more into a "muscle car". Production of the second generation Firebird continued into 1981, with major facelifts and engine changes in 1974, 1977, and 1979.

 In 1979, the Pontiac Firebird was available in four basic variants: the base Firebird, the Firebird Esprit, the Firebird Formula, and the top-of-the line Firebird Trans Am.

The 1979 Trans Am could be ordered either with an Oldsmobile 185hp 403cui L80 V8 mated to a three-step Turbo Hydramatic 350 automatic transmission, or a Pontiac 220hp 400cui L78 V8 with a 4-speed manual transmission.

A very popular option was the T-Top: a hatch roof with two big, removable glass panels. Many Trans Ams were also ordered with the WS6 special performance package, including amongst other things a tuned suspension and four-wheel disc brakes (which was somewhat oddly indicated by stenciling on the door handles!). 

 First of all, this is a BIG kit. The completed model is more than 24" long, so it will take up quite a lot of garage…sorry, shelf space.

When opening the large box you are faced with a one-piece upper body moulded in a dark brown metallic plastic, a one-piece black lower chassis and a multitude of smaller sprues with various parts in black and tan. A bunch of clear and chromed parts are also included.

The large clear plastic parts, including the windshield, rear window and T-tops, are packed separately in their own plastic bags to avoid scratching.

 The wheels are especially nice, featuring chromed "snowflake" rims and real rubber tires with raised lettering on the sides.

 Fit of parts run from good to mediocre and during construction I noted there almost seemed to be a connection between the size of part and fit; that is, the bigger the part, the worse the fit…

 Some of the larger parts (hood and rear spoiler) were warped on my example. Extreme care is required when correcting this as the brown metallic plastic is quite hard and brittle – the rear part of the hood actually cracked when I tried to correct its shape. This happened despite holding it in boiling water before any attempt was made to bend it.

The brown metallic plastic do not react very well to ordinary plastic cement either, making it a bit difficult to work with. Hence, during construction, I used super glue (cyanoacrylate) and two-part epoxy to join most of the parts.

 Instructions are in the form of a small booklet with all construction steps logically laid out.

A big decal sheet is also provided, this includes the instrument dials, all external Trans Am lettering as well as the beautiful golden hood bird.

Construction began with the interior. Fit here was quite ok; some sanding and dry fitting was required to get the parts to line up properly, but nothing that required any major applications of putty.

 The instrument panel is a chromed part and is especially nice – detailing is good and it sports the beautiful sort of "machined" surface of the real thing.

I added a very thin clear plastic sheet (coated with gloss floor wax) on the backside, and then glued the instrument decals (complete with backing paper) onto this clear sheet. When totally dry the entire backside of the instrument panel was painted flat black to prevent any unwanted color irregularities – this was necessary since the instrument decals were slightly smaller in diameter than their respective openings in the panel.

The completed panel was then attached to the dash with white glue.

 The steering column went together with little difficulty, only a little bit of adjustment to make the opening for the levers in the left side slightly bigger (as the levers couldn’t be pushed through the opening).

The steering wheel consists of three parts with the spokes being chromed; in the center of the hub I added a Firebird decal, sealing it with a coat of gloss clear varnish.

 The interior was painted and slightly weathered before adding all the chromed details, such as ashtrays, door handles, gear selector etc.

 With the interior pretty much completed I turned my attention to the lower chassis.

Construction was rapid as the entire bottom plate is a single black plastic part with various details added to it. This black plastic seemed to react better to ordinary glue than the brown metallic plastic did, so I used Testors liquid glue throughout construction of the chassis.

After the rear axle and differential housing were attached to the rear leaf springs, I put the whole chassis assembly to the side to let it cure completely.

 Then it was time to prepare the wheels. These are absolutely beautiful – the rims are made from chromed plastic and with real rubber tires.

Actually, in reality, these "snowflake" wheels are gold painted and then the outside portion of the rim is machined away, exposing the aluminum underneath. I really liked the all-chrome look of the wheels, though, so I left them as they were.

The inside part of the wheels were painted silver to imitate the rotors of the disc brakes – note that the model is equipped with the WS6 package and so has disc brakes all around.

After gluing the rim halves together, trapping the rubber tire in between, the entire wheel assemblies where attached to the respective stub axles on the chassis.

 Onto the bodywork…

 The entire body consists of only handful parts, so construction is fast. As noted before, the metallic brown plastic doesn’t react well to ordinary plastic cement so I opted to use superglue to fix the parts instead. All joints that would see substantial stress (the rear spoiler and bumper, the hood, and the nosepiece) were further reinforced with two-part epoxy glue.

As also mentioned before, the bodywork plastic is quite hard and brittle. As a result, while trying to bend the warped large hood into a more correct shape, it cracked! This happened despite holding it in almost boiling water for a long time before any attempt was made to bend it. Fortunately the crack could relatively easily be made invisible by adding a touch of super glue to it and then sanding the surface smooth.

 The hot air extractors on the front fenders were spiced up with fine plastic mesh.

 During construction of the body I also prepared it for installing working lights, adding reinforcement plates and drilling holes for the taillights between the rear bumper and spoiler. The chromed reflectors of the front high and low beam lights were also drilled to accept 5mm LEDs.

 The side position lights required some extra attention; I wanted these lights to be pretty evenly illuminated (that is, the whole area of the glass being illuminated rather than a brighter spot in the middle where the light bulb is situated) and so I decided to install dual mounted LEDs at these places.

Each pair of red and yellow LEDs were carefully sanded flat on opposite sides and then super glued together, forming a sort of dual mount. The two center legs (LED 1 anode and LED 2 cathode, respectively) were bent and soldered together.

In addition to this, I also constructed small reflector boxes, made from 1mm thick Evergreen plastic sheet. These reflector boxes serves a dual purpose: they will prevent any light from the side position LEDs to "leak" (which could be visible through gaps and such), as well as further helping to illuminate the entire "glass" of the side position lights evenly.

 Well, a car model this big just screams out for working lights, doesn’t it?

 Instead of using ordinary light bulbs, however, I opted for light emitting diodes (LED) as they don’t have as many drawbacks as light bulbs when built into a model. A light bulb will be difficult (if not impossible) to change when burnt out and it will also get warm during operation, something you do not want inside a plastic model!

A LED doesn’t really emit any heat at all and it has a life span of several thousand hours which mean it will practically last forever if not abused.

 One important difference between a LED and an ordinary light bulb is that the light bulb shines pretty evenly in all directions, while the light from a LED is more or less focused forward. So in order to "smoothen" the light all LEDs were given a gentle sanding – this roughened up their surface and gave them a nice dim appearance.

 The four headlights are each equipped with a single white 5mm LED, rated at 3V and fed with 20mA through an in-series resistor of 100ohms.

The position lights on the sides each consist of dual 5mm red at the rear and dual 5mm yellow at the front. Each dual LED is rated at 4V (2V per individual LED) and consists of two LEDs connected in series, each pair being fed with 10mA through an in-series resistor of 100ohms.

The taillights are eight 5mm red LEDs, each rated at 2V and connected two and two in series, each pair fed with 20mA through an in-series resistor of 50ohms (actually two 100ohms resistors in parallel).

 As I wanted the lighting system to be capable of running on a wide variety of external power supplies and at the same time protecting the LEDs, a simple electric control system based on the familiar 7805 voltage regulator was added. The general circuit consists of an integrated diode bridge connected to the LM7805, with a 220uF capacitor placed in parallel between the incoming connector of the voltage regulator and ground.

 This control circuit will allow the model’s lighting system to be run on anything between about 7-35 volts, AC or DC (decided by the 7805’s voltage feed limits).

The integrated diode bridge will turn incoming AC into pulsated DC, which is then ripple-reduced or "smoothened" by the 220uF capacitor. If the circuit is connected to a DC power source the diode bridge won’t do anything (except "stealing" about 1.4V).

The voltage is then regulated down to about five volts by the LM7805 integrated voltage regulator and fed to the LEDs via the in-series resistors. As the LEDs only require about 2V each and we have 5V available from the 7805 voltage regulator, the in-series resistors will help limit the current flow in the circuit and hence provide the LEDs with the correct operation voltage.

 During operation the 7805 will be emitting heat (as a result from the voltage down regulation), the amount of heat generated being about linear to the excess voltage of the power supply.

Uhu, right.

So what does this mean?

Well, the four main headlights are each fed with 20mA, the four position lights 10mA each and finally each pair of taillights 20mA (times fours as the eight LEDs are connected two and two in series). This gives a total consumption of about 200mA or 0.2Amps (not including the power consumption of the 7805 voltage regulator itself, but as it is quite low (a couple of mAs) it can relatively safely be ignored).

 This mean that the 7805 integrated circuit will have to get rid of power (thermal energy) roughly equivalent to 200mA times the excess power supply voltage.

So, how much is the excess power supply voltage then?

Well, if connected to a power source of 9V (like an ordinary flashlight battery), the excess drop voltage over the 7805 will be 9V minus 5V (the regulated voltage of the 7805) minus 1.4V (total voltage drop over the diode bridge), which equals 2.6V. The excess power will then be approximately 2.6V times 200mA, which equals just over 0.5Watt.

 In the "worst case scenario" we have a power source of 35V (the maximum allowable supply voltage for the 7805), which will give an excess power (heat) of about 5.8W. Although this doesn’t sound like too much we have to remember that the 7805 integrated circuit is physically quite small so it still can get pretty hot if run during long periods of time and with insufficient cooling (like when being mounted inside a poorly ventilated plastic car model…).

Of course, using a power source with this kind of relatively high voltage should be avoided, but just to be on the safe side the 7805 was mounted onto an aluminum heat sink (taken from the CPU of an old discarded computer).

 As I left the engine out of the model, there was plenty of room to mount the electric control circuit and all the wiring under the hood. From there each pair of LEDs were connected by thin electric wires and with the power supply cable running to the rear and ending with a 9V battery connector under the fuel tank.

As the entire kit is pretty logically divided into three main sub-assemblies: interior, lower chassis, and body, this was also the order in which I painted the model.

The interior was painted Humbrol 62 Leather and when dry a light drybrushing of Humbrol 63 Sand was added to bring out details and surface texture, especially on the hobnail cloth of the seats.

All chromed interior details received a thin coat of Johnson Plastic Floor Wax (pretty much the same thing as Future Floor Wax which might be more common for you guys in the US).

 The lower chassis was left unpainted – it is moulded in black plastic and I thought it looked quite ok as it was. Besides, you can’t really see much of it anyway as it is, well, under the car!   :)

The exhaust system with mufflers was painted in Humbrol 56 Aluminum while the opened-up centers of the chromed exhaust tips were painted black.

 The entire body was first primed in light grey. This revealed a couple of areas that needed some more attention with the sanding paper…

Then it was finally time to bring out the black paint!

The entire body was sprayed black in two consecutive sessions, the first coat being flat black and the second coat a very thin layer of gloss black. This was done in order to give the paint a more coarse and "alive" look, almost like metallic but still a solid black. When completed, the painted body was set aside to let the paint cure completely for a few days.

 After this it was time for the decals.

Applying the lettering on the hood "shaker" presented no problems, but when I started to add decals to the body I ran into some difficulties. The decals tended to "silver" badly, especially the "Trans Am" lettering on the front side fenders. I suppose this is mainly due to the fact that the decals are now pretty old (20+ years), hence quite inflexible and prone to develop small air bubbles underneath if not applied to an absolutely smooth surface. I therefore added an extra coat of clear gloss varnish on the hood and rear spoiler before any attempt was made to apply the big decals that were to go there. This seemed to solve the problem as the decals then went on nicely.

The damaged "Trans Am" lettering on the front fenders was repaired by carefully painting over the "silvered" areas with black paint, using the tip of a slightly bent needle.

 The body was set aside for a couple of days in order to let the decals dry out completely, and then the entire body was sprayed with clear gloss varnish to seal everything in.

Final assembly began with mounting the front and rear windshields to the body, then the interior "tub" was glued into place. I used two-part epoxy for this, as the body plastic didn’t like plastic cement, and I didn’t dare using super glue for fear of fogging up the windshield.

Then all the electrics were installed – headlights, side position lights with reflector boxes, and the eight rear red LEDs. The latter were simply inserted into the previously drilled 5mm holes in the internal rear plate and fixed with two-part epoxy.

 The power supply circuit was installed under the hood and all electric connections were joined and soldered. I made sure the heatsink of the voltage regulator was positioned straight underneath the hood "shaker", as the openings in this will help ventilate the engine compartment. Just as a precaution I also cemented a piece of aluminum foil on the inside of the hood, as an extra form of heat protection.

 The taillight ramp was installed and carefully cemented in place with two-part epoxy, and then the remaining chromed parts (door handles, rearview mirrors, tailpipes, and the Pontiac crest on the nose) were added. The rear red reflector below the taillight ramp was simulated by a thin strip of red "diamond" tape.

 I decided not to install the T-Tops in order to give the car a more "summer like" look.

Finally the entire upper body was mated with the lower chassis, secured with the three supplied metal screws, and the Trans Am was completed!

There you have it – a big, bad, black model of one of the coolest sports cars around (IMHO).

Considering the size of the model, construction was really a breeze and when seeing the effect of the working lights, I think the extra work involved was well worth the effort. 

  Various books and Internet resources.

 In addition, as my own experience with the 2^nd generation Firebirds is somewhat limited, I had great help from the nice people at the Swedish Trans Am Club (www.tacs.nu).

April 2008