Monogram NASCAR 1984/1985 Thunderbird

I have two NASCAR models under construction. The oldest is Monogram's 1/24 Ford Thunderbird driven by Bill Elliott in the 1984 and 1985 seasons.



The kit

I don't know much about the dozens and dozens of stock cars issued by Monogram. I've read they share a lot of parts, which could mean that the detailing is generic, but at the same time most 1:1 cars use the same chassis (Banjo Matthews in this case), suspension and drive train parts. One problem mentioned is that the roll cages don't always fit the various body shapes very well, especially around the A and B pillars. I collected the following comments from the Randy Ayers Nascar forum:


From the above I compiled the following list of problems:

During the build process I also noted that the nose is too 'square' in plan view. The grille should be more forward, creating a more pointed nose. It's an involved body modification however! The distance between the headlight and the front wheel opening is also on the short side, leading to problems with the contingency decals. If you would add 2 mm between the door and the wheel opening for the wheelbase correction, plus the modifications of the nose as just described, the front of the car would become some 4-5 mm longer, 4-5 inches in 1:1 scale. I think you would then finally get the sleek look of the real car.

Apart from some doubts about the accuracy of the kit, I like the kit a lot. It's well detailed and with suitable painting it will look very good. I intend to build the kit as an 'after-race' model, dirty, a little damaged, and with the window net down.



Differences between the 1984 and 1985 cars

Pat Campbell identified the following differences between the years:

A photo link:

Four pictures from the 1984 Nascar yearbook of Bill Elliott's car during the 1984 season:



Model's origin

In Thomas Graham's book "Monogram Models', page 129, I found some background on this model. It partly explains why the model has a lot of shape problems.  
  To illustrate the car that Banjo Matthews was working on, here's a screengrab from the movie DVD, probably by Bernie427 who posted a bunch more
The 'plucked chicken' version of the car looks horrible, and possibly has the original 104 inch wheelbase?  


Chassis construction

My main focus so far was the chassis. I deviated from the instructions to assemble the chassis as a whole. There was a bad fit interference between the lower window sill of the body and the upper bar of the sides of the roll-cage. I thinned both parts, and achieved a better but not perfect fit. The outboard edges of the floor plate were still 0.5 mm below the edges of the body sides.

Next I removed the window net, to replace it later with a more realistic one that can be draped over the side of the car. Roll bar padding has to be added too. I painted the chassis Humbrol 128, trying to replicate the color that I saw in photos. I've given the whole chassis a wash and a slight drybrush job, which makes it much more realistic.
 
  Instead of using black for the dashboard, I used Humbrol 67 dark gray. I painted the instrument panel Humbrol Polished Aluminium. The instruments were black with silver bezels and white drybrushed lettering. The ignition boxes were painted satin black.
I tried my best to make the chassis / roll cage look like one piece. I still need to do some detail painting in the engine bay, like the steering box.  
  The lower side of the chassis has the gearbox crossbeam (cut from part 27), the rear suspension crossbeam (part of part 19) and the shock absorber 'bridge' (part 57) installed. I split the rear suspension parts to be able to build and paint the chassis first. I added two transverse straps on the lower side of the fuel tank, copying the layout on the top side of the tank. The lower side of the chassis is not weathered yet.
Here the remaining part of the rear suspension is installed provisionally. I'm also fiddling with the brake calipers.  


Body construction

  Over to the body. I glued thin plastic card all around the hood to make it fit tightly. I thinned the edges of the fenders from the inside to make them look like thin sheet metal. As an experiment, I painted the hood with Humbrol 19 and polished it with Tamiya Polish. That worked pretty well, but I went through the paint in the middle of the hood. The Humbrol paint matches the plastic color amazingly well.

Not shown here is that some mold parting lines on the roof and trunk had to be removed. Also I engraved the panel line of the trunk lid on the rear panel, to match it with the depth and width of the panel line on the top side of trunk.
I glued pieces of rod on the inside of the hood, to replicate the light framework of the hood. The thick kit part spoils the impression a bit though.  
  The fit of the headlights is loose too, so I also added shims beneath the headlights. But maybe they now sit too high? I keep reading that the headlights are not correct for the 1984 and 1985 seasons, but I haven't seen a photo yet that shows what's wrong.
I reshaped the forward part of the front fenders. On the model the bottom curves inwards just like the door panel does. In reality it runs almost straight down, offering more 'coverage' for the front wheels. I used a small hair dryer to soften the plastic, and bent it gently into shape. Some Milliput smoothened the transition from the air dam to the flaired fender. I like the modification a lot: it makes the car look more aggresive.  
  A difficult modification is the removal of a rubber strip on the doors, an error that Patt Campbell brought to my attention. The street version of the T-Bird has a wide rubber strip running along the door, just below the 'slot' in the sheet metal. Monogram put it also on the NASCAR model, which definitely lacks them.

A difficult choice was whether the door panel lines should be filled or not. I had only a few photographs to base the decision on, and they appear not to show any lines. When I read that most teams were filling the door panel lines by then, I decided to do it too. I used Milliput for the job, and it's clearly not finished yet.
Removing the rubber strip is a delicate operation though, and you need to retain the small fold in the sheet metal just above it. On the left door I did 90% of the removal job. I made some 'contact damage' on the left side, consisting of impressions of another car's wheel. But I reconsidered later, and filled it in again.  
  I still wasn't sure my door is correct, so I made a drawing. I first removed the 'rubber' molding (3), which left me with a different shape than expected: the lower side of the door was now flush with the ridge (1), and there's a recessed area (2). I then added an engraved line (4), that I thought I saw in the street version of the Thunderbird. But I'm not so sure now. Maybe it should like version 3? Or maybe like version 4? In the end I went for version 5, via version 4. In version 5 the lower side of the door is more vertical and less rounded.
I glued a 0.75 mm steel wire to the bottom of the body sides, and built up the area with Apoxie. After two rounds of filling and sanding the body was smooth again. I will probably paint it red to see how the body sides now look, and whether they needs more modifications.  
  Everyone agrees that the front wheel opening should be made smaller. I sketched the modification in two versions to see how much plastic should be added roughly, and noted it was around 4 mm.
I superglued eight Evergreen strips of 1.0 x 0.5 mm to the rear side of the front wheel opening, then soaked them in more superglue to bond everything solidly together.  
  I used my low-rpm Foredom tool to create a nice curve. It's free-style, and a bit different compared to the drawing I made earlier. While motortooling I also changed the shape of the rear half of the fender. Using a sanding drum I made it concave instead of straight, making it fit smoothly with the door instead of with a kink.
Compared to photos of the real car, the bottom edge of the door window was too narrow, and I added a 1.5 mm plastic strip. At the same time I added a similar strip to the B-pillar, after sanding away the chamfer on the forward face. The rear side of the B-pillar got a similar strip, but most of that had to be cut away again to make the roll cage fit. Lastly, I sanded away the strange chamfer on the A-pillar, which created a thinner A-pillar, following photos of the real thing. I still have to modify the front corner, where the mirror would attach on a street car.  
  In the 1984 and 1985 seasons, rear side windows were not used, and therefore the flange should be removed. It was an easy modification, but it made it obvious that the main hoop is located too far aft. It's far too late to do anything about it. Maybe if you start fresh you can move it forward 4 millimeters.
In one of the 1985 Daytona photos, I noted that the the front fender's width was identical to the door width, i.e. the fender did not stick out. The rear fender seemed to exceed the door width slightly in the same photo. With a simple set-up I measured how far the fenders stick out compared to the door area. I could fit two pieces of 1 mm plastic card between the door and the bar, so it's 2 mm. That could mean that 2 mm needs to be removed from the front fender, and maybe 1-1.5 mm from the rear fender.  
  With the parts from a second kit, I built a 'dummy' assembly of the front suspension for test fitting. And quickly I noticed that the front wheels are staggered, the left wheel being forward at least 1 mm. I tried to measure the difference from the front and found 2.2 mm, and measured it from the back and found 1.2 mm, so I guess the truth is roughly in the middle, around 1.7 mm. I don't want to go overboard on small differences, but this confuses the wheelbase measurement considerably. Also because the rear axle position is a bit undefined too, the cross member with the trailing arms can be positioned with another millimeter of play. Let's sort this out before passing judgement on the wheelbase.


Wheels and tires

  Monogram supplies five-spoke wheels, whereas the real car had nine-spoke wheels. These can be found in later NASCAR models, but I did not have one. Fellow IPMS-NL modeler Martin Letterman kindly pulled a wheel of one of his models to allow me to make resin copies. I decided it would be a huge improvement to have open spokes. I disassembled the two-part donor wheel, and made two resin copies of the outer part in a silicone rubber mould. One of them I ground back until the spokes were open, and the other I drilled the center out. After some test fitting I glued them back together, and puttied the seam. This new master is the second wheel from the right. Painted copies are on the left (a Humbrol Polished Steel one, and a Model Master Metalizer Stainless Steel one), and a black resin copy on the right.

Then I found out that the original nine-spoke wheel is slightly smaller (17.5 instead of 17.7 mm) than the old five-spoke wheel. This meant that the tyre was a loose fit (you can fit two layers of paper between the wheel and tire), and it showed. I decided to try a new trick to solve that problem. I had figured out that the very different coefficients of thermal expansion of silicone rubber and epoxy offered possibilities for both enlarging and reducing parts. If the resin is left to cure in a hot mould, it will become larger, because the mould has expanded a lot, and the part will shrink much less during cool-down. Rough calculations showed that a 60 degrees Celsius temperature increase gives a 1% larger part. I needed slightly more than 1 percent, so I tried 80 degrees first. The size increase was less than expected though, and in the end I needed a 120 degrees Celsius cure to get the desired size.
Once I had a correctly sized new wheel, I made a one-part mold for the wheel. The open spokes were closed with Kristal Klear which forms a very thin skin. The mold was pretty extreme in terms of undercuts, but since it was a soft rubber type, the castings came out easily. Another lesson learned about the possibilities of resin casting. The photo shows on the left two fresh castings with the pouring stubs still attached, and three trimmed castings on the right.  
  Here's a comparison of the orginal wheel/tire set and my modified set. The Elliott car had gold wheels. I tried Tamiya enamel gold, and its looks very good. I still need to do some detail painting of the wheel, like the nuts, and an air valve needs to be added.
The brake disc was cut out of the original rear wheel part, and also copied. Six cast epoxy brake discs are shown.  
  On the inboard side of the resin wheels, there's a 2 mm boss to which the disc attaches, to recreate the disc position of the plastic kit wheel. Interestingly, I could remove part of the boss to reduce the track of the model, something that the Elliott team possibly did too.


Interim result

The result so far. About halfway I think?  

Details planned for the future:



Colors

Tamiya TS-8 is reported here as a suitable red color.



Decals

I bought an aftermarket decal sheet by RaceScale and the quality is excellent. I've been told that there is one small problem with that sheet: a red Coors decal for the TV-panel (the back of the car) is missing.



Modeling links



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