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1975 Chevy Laguna Gets A Racing Spoiler- Spoiling For Fun!

You Can Build Custom Aluminum Spoilers With Ordinary Hardware. We Show You How.
April, 2009
By Johnny Hunkins
Photography by Johnny Hunkins, Keith Kanak
1975 Chevy Laguna Racing Spoiler Rear
1975 Chevy Laguna Racing Spoiler Render
1975 Chevy Laguna Racing Spoiler Tape
A simple line of masking tape... 
   
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1975 Chevy Laguna Racing Spoiler Tape
A simple line of masking tape across the rear deck was our starting point. This is where we want the rear spoiler to mount to the decklid. The contour of the trunk changes across its surface, so we needed to first establish where the spoiler would go.
1975 Chevy Laguna Racing Spoiler Taping Spoiler
We taped two pieces of cardboard... 
   
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1975 Chevy Laguna Racing Spoiler Taping Spoiler
We taped two pieces of cardboard together and cut it with a straightedge to the height we wanted. Deciding the height was difficult; NASCAR has never published its race car specs, and only supplies this to teams. We tried to find references to spoiler height on line, but to no avail. We finally decided on a height of 4.5 inches at its tallest point-the edges. The other issue: We needed to establish a rake angle, as that determines the contour at the bottom of the spoiler. We settled on 37 degrees. We devised a similar cardboard template for the front, fitting it against the core support.
1975 Chevy Laguna Racing Spoiler Templates
The cardboard templates were... 
   
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1975 Chevy Laguna Racing Spoiler Templates
The cardboard templates were taken to Advanced Waterjet in Anaheim, CA, where they were scanned into the computer. Here, our waterjet man, Mike, cuts a test piece out of masonite before doing the real thing. This can uncover errors in the shape or the programming without ruining good material.
1975 Chevy Laguna Racing Spoiler Spoiler Pieces
Seeing our spoiler pieces... 
   
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1975 Chevy Laguna Racing Spoiler Spoiler Pieces
Seeing our spoiler pieces cut out of sheet aluminum on the waterjet machining center was a rush! We now had one-of-a-kind spoilers! Getting custom waterjet parts is less expensive than you might think. These two spoilers cost us $200, included the small pieces for the struts. To get a quote on custom work, you can call Advanced at 714-278-9874.
1975 Chevy Laguna Racing Spoiler Metal
Back at the garage, we mocked... 
   
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1975 Chevy Laguna Racing Spoiler Metal
Back at the garage, we mocked up the front spoiler several times, marking our mounting points on the core support and drilling holes. We also carved out some clearance (center) for a brace on the core support we overlooked before. Some scrap flat stock was pressed into service to make four angled mounting tabs that attach with quality button head fasteners from the local Ace Hardware. We went to Ace Hardware a lot.
1975 Chevy Laguna Racing Spoiler Mounting Tabs
We tagged the homemade mounting... 
   
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1975 Chevy Laguna Racing Spoiler Mounting Tabs
We tagged the homemade mounting tabs with Dupli-Color satin black and assembled the tabs on the spoiler one last time. Once all the mock-up was completed, we grained the spoiler with a Scotch-Brite pad and some WD40 to give it a nice sheen.
1975 Chevy Laguna Racing Spoiler Four Mounting Tabs
The four mounting tabs can't... 
   
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1975 Chevy Laguna Racing Spoiler Four Mounting Tabs
The four mounting tabs can't handle all the aero load, so we fabbed some diagonal braces out of quarter-inch bar stock and some flat washers. It's just a matter of mocking up the spoiler with the washers attached to the spoiler and the car, cutting the bars to length, and tack welding it to the washers. Off the car, the braces were welded, smoothed, and painted.
1975 Chevy Laguna Racing Spoiler Front Spoiler
Voil! Custom front spoiler... 
   
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1975 Chevy Laguna Racing Spoiler Front Spoiler
Voil! Custom front spoiler with side braces. We later drove the desert between Phoenix and Los Angeles in August, and experienced zero overheating. This spoiler performs cooling duty by ducting cool air across the radiator.
1975 Chevy Laguna Racing Spoiler Taped Spoiler
Out back, we mocked up the... 
   
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1975 Chevy Laguna Racing Spoiler Taped Spoiler
Out back, we mocked up the spoiler and found the shape of our waterjet piece matched our curved trunk perfectly. Here, PHR contributor Keith Kanak checks the angle in preparation for attaching the hinges and struts.
1975 Chevy Laguna Racing Spoiler Piano Hinge
You can get these piano hinges... 
   
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1975 Chevy Laguna Racing Spoiler Piano Hinge
You can get these piano hinges at Ace Hardware for about a buck, and they were per-fect for the rear spoiler after we cut the corners off, bent them to curve to the trunk lid, and painted them-what else-satin black.
1975 Chevy Laguna Racing Spoiler Threadsert
After we worked the hinge... 
   
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1975 Chevy Laguna Racing Spoiler Threadsert
After we worked the hinge into shape, we marked the mounting position on the spoiler and trunk lid, then carefully drilled and crimped our threadsert mounting points. We used an 11/64-inch drill bit for these holes, and filled them with 8-32 threadserts. These handy pieces will allow us to screw our hinges right into the decklid.
1975 Chevy Laguna Racing Spoiler Hinges
Note how we're using masking... 
   
  read full caption
1975 Chevy Laguna Racing Spoiler Hinges
Note how we're using masking tape to constantly protect our paint, as well as mark the line of the spoiler. Here you can see how we attached the reworked Ace Hardware hinge to the threadsert with 3/32-inch hex-head button fasteners. Anybody else find it funny that Ace sponsored the IROC race for years? We bet they supplied the hinges.
1975 Chevy Laguna Racing Spoiler Mounting Holes
Under the spoiler, we marked... 
   
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1975 Chevy Laguna Racing Spoiler Mounting Holes
Under the spoiler, we marked mounting holes for the hinges where they attach to the spoiler. The key thing is to carefully measure the distance between the spoiler and the decklid: we needed it to fit tight, but not so close that it binds on the paint when it's adjusted.
1975 Chevy Laguna Racing Spoiler Various Parts
1975 Chevy Laguna Racing Spoiler Strut Assembly
This was the difficult part:... 
   
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1975 Chevy Laguna Racing Spoiler Strut Assembly
This was the difficult part: taking the pieces you see in the first photo, and making it into what you see in the second one. When we had our spoilers waterjetted, we also provided a design for a strut mounting bracket (the two triangles and rectangle with holes). We TIG-welded the three pieces together to form a U-shaped bracket that could retain one end of a small Heim joint. We made 10 aluminum brackets and 5 strut assemblies in all. The strut assemblies were made from 10-32 Heim joints (5 right-handed, 5 left-handed) that were screwed into 1/4-inch aluminum rod which we tapped with the appropriate dies. The tie-rod ends cost $5.50 each, and the jamb nuts were $15-all supplied by Ellis Racing in Phoenix (800-969-0450).
1975 Chevy Laguna Racing Spoiler Drill
It pays to slow up here, and... 
   
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1975 Chevy Laguna Racing Spoiler Drill
It pays to slow up here, and mock stuff up at the proper spoiler angle. Before drilling the threadsert holes for the strut mounts, we had to consider the spoiler angle, the amount of spoiler adjustment range, the cosmetic angle of the struts, and the length of the strut rods themselves. Then we drilled!
1975 Chevy Laguna Racing Spoiler Fasteners
Good-quality hardware isn't... 
   
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1975 Chevy Laguna Racing Spoiler Fasteners
Good-quality hardware isn't expensive, and we chose the best stainless Allen-head fasteners we could find. After crimping in our threadserts, we bolted on our homemade mounting brackets with no problem.
1975 Chevy Laguna Racing Spoiler Locking Nuts
We finished off our strut... 
   
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1975 Chevy Laguna Racing Spoiler Locking Nuts
We finished off our strut braces with nylon-locking nuts and more stainless hardware for the heim joints and mounting brackets.
1975 Chevy Laguna Racing Spoiler Finished Spoiler
Not too shabby for a homegrown... 
   
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1975 Chevy Laguna Racing Spoiler Finished Spoiler
Not too shabby for a homegrown spoiler. We set the angle at 37 degrees by twisting the strut tubes and locking down the nuts. Our Laguna has Neil Bonnett's name on the roof (he drove a Laguna throughout the mid-'70s), and according to people who knew Neil, he would often lay the spoiler flat during qualifying-and sometimes during racing-to get faster lap times. That would often result in extremely loose handling, and lots of pucker factor for all involved!
Advanced Waterjet

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