Building an "A" type hip-spoiler for the Manta

[Blueovalz]

When I finished my six year Manta conversion into a look-alike Mclaren, I no longer had the wherewithal to start on the M8A spoiler. I didn't want a wing to match the "B" body being this was mostly a street car, and the "A" spoiler is unique enough to compliment what had been accomplished already. So three years later, and having thought about how I would build it, yet not make it weigh a ton, and not being satisfied with a similarly shaped aluminum one that just wouldn't be "right", I dove into this mini-project. As it turned out, this seemingly simple idea and piece was probably one of the more complicated parts I've built for this car. Based on some very good scale drawings and photos, I came up with the dimensions, which appear to be reasonable once I was able to visualize it with foam-board template taped to the car:




One of the many challenges was to build this to fit the car like a glove, yet fabricate it without destroying the existing paint. This was done by carefully laying up masking tape to cover the existing paint, very evenly, anywhere fiberglass would be laid. Then I laid up a mounting flange onto the tape, which would be used to fasten the completed spoiler in place using 1/4" screws around the periphery of the mounting flange. The subsequent pieces of the spoiler would be bonded onto this mounting flange:

[Blueovalz]

Next up was to build the "down-planes" as I call them; the side pieces with a slight angle to them. They had to be bonded onto, and thus become another layer of the mounting flange sides. In order to save as much weight as possible, I had to make the spoiler hollow,which means I had to build two plates, or panel faces for every aspect of the spoiler, two surfaces for each side's down-planes, plus a front and rear-facing plate for the main spoiler panel. The passenger-side down-plane, top and bottom plates:


Once I completed the down-planes, I laid up the front and rear-facing plates for the main spoiler panel. I used a sheet of .125" aluminum as a buck to obtain a smooth even finish on each plate's exterior side. These plates had to be at least 83" wide, and are roughly 1/8" thick (4 layers of 2 oz mat + a couple of layers of thin cloth):


To ensure the front and rear-facing plates would be at the proper angle, I hot-glued some wood guides in place, and then bonded the rear-facing panel onto the mounting flange. The goal here was to have the front-facing panel be parallel and aligned with the angle of the body's rear lip and integrated spoiler already existing. My goal was to simply continue that angle upward another 6.5" taller:

[Blueovalz]

After the rear-facing panel was bonded in place, I installed threaded inserts into the mounting flange for additional insurance that the spoiler would stay in place at high speed. First I located the inserts, then wrapped them in fiberglass so that they were bonded to the mounting flange. Once this was done, I could go forward with bonding the front-facing plate:


I then bonded the front-facing plate in place, using spacers, between the front and rear-facing plates, all along the edges to ensure the spoiler would have uniform thickness along the entire edge and into the down-planes:

This is where the project is at this time. Next addition will be a cap along the entire periphery of the spoiler to tie the front and rear-facing plates, as well as the upper and lower down-plane plates. The original spoiler on the team cars use wood as a core. I will fill mine with expandable foam. The spoiler will be about 5/8" thick at the edges throughout the entire assembly, but will be thicker at the base of the main panel to ensure rigidity against rearward force from oncoming air at speed. A total of 6 internal 1/4" bolts, and 29 external screws (similar to the team method on the external screws) will affix this spoiler in place. The main deviation from the team spoiler design is that I will use the internal bolts (using the inserts with bolts coming up through the bodywork from under the bodywork), and the fact that this is a one-piece spoiler instead of two halves being joined in the middle. Anticipated weight will be 25 lbs.

[Blueovalz]

With cap installed, and with most external fasteners in place, but not finished:










To ensure the body under the spoiler was sufficiently strong to handle the forces imparted into it from the spoiler, I've added two perpendicular flanges (3" deep) on the inside of the rear vent panel, that extend from the upper rear body lip, down to the lower valance, and which are used with two 3/8" bolts to hold the rear of the body panel in place (as well as act as hinges).

[marfen]

nice work. great car.

[CoyoteX]

Awesome!

[Blueovalz]

Fiberglass work is pretty much finished at this point. Ready for Duratec, finish-sanding, and paint. Final weight came in at 24 lbs without paint. Will be moving forward with perhaps some quickly fabricated fences for the front bodywork to improve that end's downforce as well:

[marfen]

I really like this build. I think making scoops functional, adding spoilers that work and other functional body mods really take the "kit" out of the car body mold and take it to a new level.

[marfen]

What do you do for filters on your stacks?

[Blueovalz]

The current set-up is triple screens at the top of the tubes (progressively finer mesh). I have no idea of how much efficiency is lost being screen isn't that efficient for passing air. I occasionally run K&N stack filters, which I'm sure is more effective and efficient, but it really detracts from the CanAm look, and as little as this car is driven, not sure in the long run how much different engine wear would be.