Last month we introduced our latest project, an '85 LX coupe. Destined for the open track, our max-effort, four-eyed Fox will also be required to perform just as well on the street. We laid out a few of the core components, including the FRPP Coyote crate engine and Controls Pack, Tremec T-56 Magnum transmission from American Powertrain, and a slew of stuff from Kenny Brown Performance (KB).
Along with showing you some of the parts, we also provided a few options for paint scheme in renderings by John McBride. And to make things even more interesting, we haven't even chosen a name for the project yet. Hopefully, you read our first installment and sent in your ideas.
Next on our agenda was to get cracking on the car itself. Since the engine and transmission were already removed, we started on the interior. The few pieces that we are going to reuse need to be dyed black anyway, so we went ahead and stripped the interior bare. Except for the parking brake assembly and steering column, nothing remained.
We removed and set aside the engine and chassis harnesses, as some will be reused and others modified later to accommodate our FRPP Controls Pack. We'll be rerouting and hiding as much as possible, as we'll be giving just as much attention to detail as any other project we've ever done.
Since the framework of the build will be constructed using a combination of chassis-stiffening and safety components from KB, it seemed only rational to do that next. A phone call to Kenny Brown himself validated our hypothesis. "Think of building a car like building a house," says Brown, "and the chassis is like the foundation. You don't build a house until you pour a good, solid foundation."
Using a four-post lift, we...
Using a four-post lift, we installed the Extreme Matrix System from Kenny Brown Performance on our ’85 LX coupe.
When it comes to the flexible properties of the Fox chassis, a solid foundation is what you need for extreme-use builds like ours. The disco-era uni-body design of the platform is great for street and light track use, but leaves a lot on the table when stepping up to extreme use like ours will see.
"The Matrix System places four full triangulations on each side, which provides exceptional rigidity," says Brown. This allows the suspension to work as designed, without unpredictable reactions caused by flex in the chassis. And at only 45 pounds, the benefit overshadows the weight addition. "The weight is low and in the center of the car," says Brown. "This helps handling immensely."
Before we just started welding in all this cool stuff, we gave the underside a good cleaning. And we don't mean just spraying it down with some brake parts cleaner or washing it with soapy water and a rag. We used professional-grade cleaners and degreasers, as well as a 2,200-psi pressure washer, which worked well. Short of removing the factory undercoating, our coupe's belly was as clean and smooth as ever.
Since the six-point Street Cage was a prototype for the new KB line, we wanted to make sure the mounting bolts wouldn't interfere with the Matrix brace. So we installed the cage using the provided hardware, but tightened the nuts and bolts by hand only.
Pre-fitting the Matrix system proved that the two would, in fact, interfere. Kenny Brown is using our feedback to correct the problem, so you won't have to worry about this issue. But we're going to weld ours in place anyway.
With all of our now-unnecessary rollbar hardware out of the way, we began installation of the Extreme Matrix System. Our coupe had a set of subframe connectors already installed, but because they won't work with the KB Matrix System, we had to remove them.
Mocked in place with locking C-clamps, we tacked everything in place first. After ensuring no other problems would arise, we welded everything in place.
Something else to consider are brake lines. The stock rear brake line must be moved aside to install the Matrix on the passenger side. Since we removed ours (as well as the stock fuel lines), we'll just find a new routing for our new ones or have custom lines made when the time comes.
Check back next month as we mock up the engine and transmission. We'll also finish up the engine bay, paint the underside, and pre-fit our new A/C unit before we send our coupe to paint.
1. Before we laid one weld...
1. Before we laid one weld or drilled one single hole, we wanted to make sure this baby was clean. There’s nothing worse than installing brand-new, clean parts on an old, greasy car.
2. Here's the underside after...
2. Here's the underside after we soaked it with a barrage of commercial-grade cleaners and degreasers—according to the directions on the label, of course.
3. We then used 2,200 psi...
3. We then used 2,200 psi of water to blast away the quarter-century of grease, grime, and gravel.
4. Our spring cleaning revealed...
4. Our spring cleaning revealed a few stress cracks in the floor—a couple near the driver-seat brace and a few in the tunnel between the torque boxes.
5. We drilled holes at each...
5. We drilled holes at each end of every crack to stop its progress.
6. Then we sanded the paint...
6. Then we sanded the paint away.
7. Next, we welded the cracks...
7. Next, we welded the cracks using a TIG welder, which allows more temperature control when butt-welding thin sheetmetal, like a floor.
8. The Street Cage was next....
8. The Street Cage was next. We raised the main hoop into place against the step in the floor where the rear seat mounts, and bolted it in hand-tight.
9. Using a 2.5-inch hole...
9. Using a 2.5-inch hole saw, we drilled holes in the rear seat brace for the rear bars.
10. Then we cut the rest...
10. Then we cut the rest away with an air saw.
11. After lightly massaging...
11. After lightly massaging the seat brace with a hammer, the bars fit just fine. If we were installing ours permanently now, we would have drilled holes and bolted these in place.
12. The door bars then slide...
12. The door bars then slide into the main hoop and bolt to the floor. We marked and drilled the holes for the door bars, and then bolted them in place hand-tight.
13. Here is the final product....
13. Here is the final product. Made of 1-3/4-inch 0.095-wall DOM steel, hand-welded, and wrinkle-black powdercoated, the Kenny Brown Performance Street Cage (PN KB-39003; $799) is clean, classy, and functional. It is designed to make use of the back seat easy, but for more serious drivers, the harness bar and crossbrace are optional at $50 each. There will also be an option if you have a hatchback (PN KB-39001; $799). If you have an SN-95 or New Edge (PN KB-39201), or an S197 (PN KB-39601), KB has you covered as well.
14. To stiffen the inherently...
14. To stiffen the inherently flexible Fox chassis, we chose the Kenny Brown Performance Extreme Matrix System (PN KB-29550; $359). Consisting of subframe connectors, jacking rails, and matrix braces, this six-piece kit is both lightweight (under 45 pounds) and sturdy.
15. Once we installed the...
15. Once we installed the subframe connectors by attaching them to the seat brace with provided hardware, we tacked in the jacking rails and pre-fit the matrix braces. They are intentionally left long so the customer can cut the bars to length. Since most of these cars are slightly different, it’s better to have a little extra material than not enough.
16. Holding the matrix braces...
16. Holding the matrix braces in place with locking C-clamps and a floorjack, we then tacked everything in place using a MIG welder. The MIG penetrates the KB components’ silver coating just fine, but you should grind away any undercoating and paint on the underside where you plan to weld.
17. We then finished welding...
17. We then finished welding the components to each other and the car, being sure not to stay in one place too long. It is easy to burn through when welding to sheetmetal, so be careful.
18. Here is the passenger...
18. Here is the passenger side completely finished. Next month, we’ll paint the entire underside of the car to hide our ugly welds. We’re also going to mock up the engine and transmission, as well as finish smoothing out our engine bay.