As the subject indicates, I am wondering if anyone knows why GM made the 1985-1990 Formula/Trans Am/GTA aero wing out of rubber instead of fiberglass? It is heavier than fiberglass, and over time breaks down and loses its shape.

 

Technology

 

My guess would have to be cost. That's usually the prime motivator in most decisions.

With that rubber crap, it can be quickly and easily made with an injection mold. Polyurethane wouldn't have the rigidity with that sort of shape, and the fiberglass would need to be done in 2 pieces and put together, which would raise expenses. Even a plastic mold would need to be done in 2 pieces and put together, which I'm guessing, would have cost more than just squirting 50 pounds of low quality rubber junk into a single mold.

 

like many things it may have gone to the lowest bidder.

Although I really do not think it was an issue of price...

If you look at the Trans Am from 1985 thru 1990 you will notice the following: The ground effects are all moulded urithane, In some ways it is superior to Fiberglass because it is less prone to cracking and getting damaged if bumped. On the 82-85 Trans Am cars and on the base firebird the basic Wing was made from several pieces of Fiberglass bonded together.

The camaro on the other hand all of its ground effects to my knowledge were made from Fiberglass...

Matter of fact I think the aero spoiler may have been slightly more expensive, However the added weight on the rear of the car may have helped to more evenly distribute the weight for more predictable handling. If you notice in 1991, the 1LE cars came with a slightly smaller rear anti-roll bar because of an understeering issue, although ideally the cars would be similar to the earlier cars. The added weight of the aero spoiler would have also helped improve ride.

Why not Fiberglass:
The wing spoiler and the ground effects on the Camaro and the spoiler on the camaro were all made from Fiberglass. Camaros are not as expensive as Trans Am's, and therefore they might have gotten rubber parts if it was cheeper.

With all that said I do not think it was price that determined the spoiler, I think it was a different philosophy between Chevy & Pontiac.

John

 

Initially that spoiler was black only, and I dont think they put a finish on the early ones, so it would be a cost issue. Make a ton of em one color and send em out the door.

BTW I like your avatar

 

They were probably Black initially because all Trans Am spoilers/Wings were Black from 1983 thru 1986... You are probably correct in assuming that they were unpainted as they had a tecture, they were made from Black urithane and why paint them.

However, the door bump guards on my 87 are actually cast yellow, you can take a rasor and shave off 1/4" and its still the same color yellow as the car. I believe they used that type of bumper guard thru 1992, that were actually cast the color of the car. However if the car had a metalic flake in it they had to paint them, as I remember the bump guards on my 91 were painted, however they were moulded in a blue color.

I am leaning toward thinking it was not cost... As setting up a fiberglass mold to knock them out would have been cheeper for the dies, less material would have been needed, if it is cheeper, why are all of the aftermarket ones fiberglass?

In many ways a solid Rubber Aero Spoiler would have benefits, as it would not be so prone to breaking, However they included a steel frame that when it rusts it expands and then causes splits. If they would have used aluminum, or Stainless steel as a frame, I would think the spoiler would have lasted the life of the car. Its definately speculation, but really thats all this thread is about, there are no hard facts to support one arguement over another.

 

Everything is urethane except the pieces on the doors, they are fiberglass.

 

They definitely were not painted, not until 87 anyway.

 

Not true.
The 84-85 standard rear wing was painted body color.
And yes, the 85 T/As began production with the 82-84 style wing,
before the Aero spoiler was introduced.

Leon.

 

I stand corrected...

But there is a pattern...

82-83 T/A Black Wing
85-86 T/A Black Aero Spoiler


It may have been a cosmetic thing where they would slowly improve the looks of the car, like many other models, it gives the car freshness and boosts sales...

John

 

The early wrap around rubber spoilers had a weird pattern to the finish, I remember. Not very smooth.
The painted ones are very smooth.
Another strange thing that I have not been able to find out about, is that I have some Pre-production photos of the new wraparound rear spoiler on a Trans Am for 1986, and it has the center mounted under the spoiler third brakelight, which came out in 1987, not in 1986. In the photo, the plate shows 1986.
1986 got the top mounted glass hatch center third brakelight.
The painted wraparound rear spoilers seem alittle bit stiffer, and not as rubbery.

My take,

George

 

U people are leaving on thing out.

They determined this thru lots of expensive testing.



Without the extra 20 lbs# of steel bar reinforced spoiler, the rear hatch falling on your head when the hatch struts inevitably let go would only hurt you, with the extra weight, it is set for maim or kill :-) lol


My guess for a real answer would prolly be cost. The rubber back than for the spoiler was prolly cheaper than a 2 piece spoiler made from fiberglass. Materials may/may not have been cheaper, but cutting out man power might make the difference? Who knows.

Course, maybe they were using it as an experiement from the factory? I cant think of any other GM product from than that had self imploding spoiler options. I guess we will never know and just have to theorize unless someone involved ever speaks up or is found.

Another one, is cost may not have been an issue, with them using the spoiler on the higher line TA and GTA(which was a good chunk of change more in the day) even with higher prices, it would pay for itself in highly optioned cars one way or another.

later
Jeremy

 

the extra weight and top speed go hand in hand
think what Pontiac was doing back then with these cars @ the salt flats

 

I am kind of torn on this as my aero wing is definitely showing signs of decay, and I'd like to replace it but would rather not spend $350 for a fiberglass replacement-plus another $100 or so to have it painted. I'd also rather not buy a used one and run into this same problem in a few years. I am leaning towards replacing it with the staright wing spoiler from the earlier Trans Ams (1982-1985) or from a later Firebird.

That being said, is the regular wing spoiler from an 84 or 85 a direct bolt on replacement for the aero wing- do the holes match up or is there some bondoing involved to cover the old holes?

 

George brings up an interesting point, The 85 & 86 Wrap around spoiler have a texture. If you look at the textrue, I think its the standard bumpy texture that was used on the Bumperetts on the Firebird, Formula & S/E from 85 - 90. IIRC This texture is also similar to many GM vinyl surfaces such as the Dash Pads in our cars...

When it was decided to Paint the spoiler, Pontiac may have decided that since they already had an investment in tooling, to simply make the spoiler from the same materials, and not re-invent the Wheel ( or the Spoiler in this case.

To follow the logic, when making something out of Fiberglass there are several things that happen that most people are aware of. For example, Things coming out of molds made from fiberglass are usually not "Perfect" by themselves. For this reason many things such as small voids are corrected by some filler and sand paper. On a rough surface, such as the 85-86 Aero Spoiler, correcting these problems is quite difficult.

Soft Urithane parts are usually made with a Bag. How the system works is you have your mold, and the Urithane is injected into the mold until over full.

Once the mold is full of liquid urithane you put the part and the molds under an extreem vacuum. What this does is it removes the air from the liquid, essentially boiling the liquid. This reduces the number of bubbles and pockets in the part, it also helps the material to get into the small crevices. When the part has had a time to expell most of its air, the pressure is slowly increased to Atmospheric pressures, and the small bubbles that may have been presant under vacuum become much smaller or disapear to almost nothing.

The part would probably be then placed in an autoclave. In the Autoclave the part is both heated and put under pressure at the same time. The Heat helps reduce the cure time, the pressure takes those small bubbles and makes them even smaller. Once the part is cured it is removed from the mold, trimmed of excess material and then the mold is cleaned for the next part.

If you think by putting the part under pressure might make it smaller, think back to physics, you cannot make a solid or a liquid smaller by compressing it. The only thing you can make smaller is a Gas, IF there is no gasses left in the solution the size would stay the same.

Next week we will discuss injection molding and interior trim pieces.

John

 

The rear 2 holes that were used on the standard wing are in the same place as the rear 2 holes of the AEro Spoiler, However you need to drill 2 more holes for the standard wing.

In my opionion the Fiberglass aero spoiler is the way to go. If you install a standard wing, the car looks like a Base Firebird with ground effects and a trans Am hood.

John

 

I cant say for sure if the holes line-up or not, but if they don't, the old holes will have to be welded shut.
What ever you do, don't "bondo" them shut. It will just break out and look like crap in no time.
When it comes to body work, there's only one way, and that's doing it the right way.

Leon.

 

There was a textured finish, but I dont know that the later spoilers didnt have this finish. Its not deep enough that a couple priming jobs wouldnt wipe it out. Mine has 'worn off' in some areas and it looks like open cell material to me so they at least had to put something on there, maybe without the texture, to paint the spoiler.

 

My 87 was smothe, I remember that because I sanded it down to the rubber past the primer to get all of the flex cracks out of it. When I got down to the primer there was nothing to suggest that it was originally textured.

John