Surely you’ve had plenty of aha moments in your life, when you realize something that’s as true and as pure as the day you passed your driving test to get your first license. As we have throughout the build of our Factory Five Racing Mk4 Cobra, we’ve enjoyed countless of these profound events. The most impactful of these epiphanies is the enduring notion that we’re building an automobile from a prodigious collection of parts, now located in perhaps 50 or so boxes, a chassis, and four BFGoodrich Radial TA tires. We’re going to be counting on the fact that this Cobra replica is going to be safe, reliable, and fun to drive.
This Tech Tip is From the Full Book, HOW TO BUILD COBRA KIT CARS + BUYING USED. For a comprehensive guide on this entire subject you can visit this link:
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We don’t expect it to be a milesper-gallon champion, but it should be a well-constructed and solid road burner. And it should be as solid as if Factory Five Racing had built the car. It’s a profound notion to wrap your head around. For this huge reason, it’s of utmost importance that we resolved to be painstakingly careful at every phase of the roadster’s build.
Firewall and Footbox
There are 62 aluminum panels in the Factory Five Racing Mk4 roadster. When we marked, drilled, and removed the overlapping preinstalled panels from the Mk4 chassis, we did grow rather weary of disassembling all these panels. This was likely due to our having to really concentrate and be diligent about accurately marking and drilling the appropriates panels, so that we could begin to put the 3-D jigsaw puzzle back together.
We were really excited to get the aluminum panels riveted in place, because we could then see the car take shape. It was also interesting to find out how well we marked the aluminum. We found this out by installing the firewall and the front of the driver’s front footbox panel.
Project 1: Footbox Panel Installation
Step 1: Old Footbox Front Panel
You need a drill, a 1/8- inch drill bit, a riveting gun, silicone, and a caulking gun. These tools are required to install the firewall and driver’s footbox panels, and secondary body fasteners into place. After marking the firewall for drilling with the FFR-supplied piece of ruler-size aluminum that has the 2- and 3-inch spaced holes, drill the panel off the chassis. At this step, you’re drilling the holes in the aluminum firewall panel to serve as a guide for drilling into the powdercoated square-frame tube. Then weave the silicone around the drilled holes. Fasten the firewall panel with one of the sheet-metal screws that originally held it into position. Also use a clamp or a helper to hold the panel in its proper place, before drilling the rest of the rivet holes into the square chassis tubes. Drill the holes and then install the rivets with a rivet gun. Some of the holes may need to be enlarged with an auger.
Step 2: Front Footbox Driver-Side Panel
Here is the installed front driver-side footbox panel. Install it by marking, drilling, siliconing, and riveting the panel into position. Take your time so the panels are properly aligned. Don’t silicone or rivet the bottom inside wall; the engine bay inside-wall panel slips underneath this panel a bit later in the build. Please ignore the components attached to our front footbox panel. We mistakenly marked, drilled, siliconed, and riveted the front footbox panel that was pre-installed in the chassis. This replacement panel was in one of the boxes. If you’re building an FFR Mk4, Factory Five has this panel preinstalled, and you won’t make the same mistake we made. Also notice the brushed finish to our panel. We sanded every panel with 180- grit sandpaper and applied Sharkhide metal protectant to all the panels that are not covered. Sharkhide is easy to apply and protects any unpainted metal for 10 years or more. It gives the metal a satin shine, which, like the one we built sets your Cobra replica apart from all others.
Pedal Box Assembly
Consider the installation of the pedal box assembly. The Cobra better go when the accelerator pedal is pushed, and it better stop swift, straight, and true when you step on the brake pedal. Every system that’s constructed and/or installed must be done correctly so all the systems work harmoniously and without flaw.
Project 2: Pedal Box Assembly Installation
Step 1: Inspect Pedal Box Assembly
Factory Five Racing supplies a well-made Wilwood pedal-box assembly in the Complete Mk4 kit that is designed to use a cable clutch. You can use a mechanical clutch or install a hydraulic clutch. The pedal-box assembly installation requires: pedal box hardware; supplied bare steel brackets; pedal box assembly; 1/2- and 9/16-inch sockets; 3/8-, 11/32-, 1/2-, and 9/16-inch wrenches; 3/16-, 1/4-, and 1/2-inch drill bits; electric or air drill; 1/8-, 9/32-, 3/16-, and 5/16-inch hex keys; hammer; workbench vise; razor knife; file or grinder; and the trusty and elusive snap-ring pliers.
Step 2: Paint and Drill Hole in Brake-Switch Bracket
Rust is not your friend, so spray paint the supplied bare-metal brackets with black paint. Factory Five Racing recommends using gloss-black Rust-Oleum paint, as this is the closest match to the gloss-black powdercoated chassis. Use inside and outside snap-ring pliers to remove the retaining clip from the brake-pedal pivot sleeve, then pull the sleeve and remove the pedal. Next drill a 3/16-inch hole in the brake switch mount. Use the workbench vice and wear safety glasses to do this operation in the safest and best way.
Step 3: Install Brake-Switch Mount
Install brake-switch pedal mount between the brake-pedal mount tabs closest to the brake-pedal pivot holes with the black number-8 screw and the appropriate hex key and locknut. Notice we also painted the brake-switch pedal mount gloss black after drilling the 3/16-inch hole in the mount.
Step 4: Install Brake Switch and Brake Pedal
Attach the brake switch with the provided fasteners and reinstall the brake pedal. Use your snap-ring pliers and the snap rings to safely secure the pedal arm. We were unable to reinstall all four washers but could get three washers into place. Although we tried several times to get the inside washer to stay in place while routing the pivot sleeve into position, the washer kept falling out. After installing the three washers, we confirmed that the pedal action was still smooth and without any slop. Perhaps you can install all four.
Step 5: Remove Snap Ring and Bore Out Clutch Quadrant
The FFR Mk4 assembly manual indicates that the provided longer pivot sleeve gets a retainer ring attached to it. Use this pivot sleeve to locate the clutch quadrant, if you have a mechanical clutch. If the pivot sleeve does not fit through the attachment hole in the clutch quadrant your next step is to bore out the pivot sleeve hole in the clutch quadrant by holding it in the workbench vice and boring the hole with a 1/2-inch drill bit and the electric drill.
Step 6: Install Retaining Ring and Washers
After precisely honing out the clutch quadrant to accommodate the longer pivot sleeve, install the pivot sleeve into the clutch quadrant and retaining ring in its proper place on the end of the pivot sleeve. Install the ring with snap-ring pliers. A supplied copper/Teflon Wilwood pedal washer is in its correct position on the other side.
Step 7: Attach Wilwood Pedals to Bracket
Three button-head bolts with locknuts and one stud with a locknut attach the Wilwood pedals to the underside of the pedal-mounting bracket. (Notice we’ve painted our bracket gloss Rust-Oleum black to prevent rust.) If you’re using a cable clutch, make sure that you install the stud underneath where the clutch-pedal pivot sleeve boss goes. Tapping the stud with a hammer and punch secures it so you can tighten with the supplied locknut on the other side. We already had the clutch-pivot sleeve boss and clutch quadrant installed in this photo, but realized we had installed the stud in the wrong way. With the stud installed properly, the assembly should appear as shown.
Step 8: Attach Clutch-Pedal Stop Mount
Using the provided 1/4-inch socket-head screws and locknuts, simply screw the clutch-pedal stop mount to the bottom of the pedal box. Torque the locknuts to the specified amount in your assembly manual. We torqued the nuts to the FFR-specified 50 ft-lbs. As the FFR assembly manual indicates, you may need to file off the stud end so the clutch-quadrant aluminum pivot sleeve clears the stud end. Notice in the previous photo that we did need to perform this operation.
Step 9: Inspect Pedal Box Hardware
Installing the pedal box assembly with the supplied pedal box hardware is a relatively easy job. All of those fasteners look like overkill, but we didn’t have any left over.
Step 10: Drill Holes and Install Pedal Box
When placing the pedal box in the chassis, make sure that the brake pedal is in front of the 3/4-inch cross tube on the frame. After the pedal box is in place, mark the rear mount holes of the pedal box assembly on the 3/4-inch tubes. Then remove the pedal box assembly and drill the holes. The FFR Mk4 assembly manual does this process a bit differently than we did. Understand both procedures and then be sure you don’t make a mistake. After drilling the rear pedal-box mount holes, install the pedal box with the four 3/8 x 1-inch socket head screws through the front of the footbox wall. Install the locknuts that hold these bolts in place on the inside of the footbox. Also install the rear mount fasteners, since you’ve drilled the holes in the frame tubes.
Step 11: Install Brake Master Cylinders
After threading a jam nut from the Wilwood pedals fasteners onto each of the Wilwood mastercylinder shafts, turn the threaded shaft into the threaded mount on the brake pedal and secure the master cylinder with the supplied fasteners. Repeat the threading and installing operation with the other Wilwood master cylinder into the pedal box assembly.
Step 12: Tighten Pedal Box/ Master Cylinder Fasteners
With all of the fasteners in place for the pedal box assembly, secure them with hand tools and torque each fastener to the torque specs in your Cobra kit’s assembly manual. Perform a careful visual inspection of the entire assembly before tightening all of the nuts and bolts, to be certain that everything lines up properly and the assembly is correctly installed.
Step 13: Install Screw-in Quadrant Pedal Stop
Next thread the jam nut onto the 3/8 x 1.25-inch screw that FFR provided in the quadrant box. Push in from the bottom of the clutch-quadrant pedal-stop mount and install the clutch-quadrant pedalstop screw, with the locknut hand-tightened for now.
Step 14: Mount Clutch-Cable Adjuster
Push the firewall-mounted clutch-cable adjuster through its opening in the front wall of the footbox, and then use a 9/64-inch hex key and an 11/32-inch wrench to attach the screws to the firewall. If you’re not using a cable clutch, this installation is unnecessary.
Step 15: Pull Rubber Mount off Clutch Cable
Now that the clutchcable firewall adjuster is in place, you can install the clutch cable into the clutch quadrant. Start by removing the rubber mount from the end of the clutch cable. Use a razor knife, file, or grinder to smooth out the cable end before the clutch cable is installed.
Step 16: Install Cable into Quadrant
With the plastic now smooth, you can slide the clutch cable through the adjuster and place the cable end back from the quadrant.
Step 17: Install Accelerator Pedal
Separate the arms after unpacking the throttle pedal. To fit the box, you must fold the arms. The accelerator pedal sleeve needs to be removed and re-positioned, so that the arms are as shown here. When re-assembling the arms with the 1/4- x 3/4-inch screw and locknut from the pedal box hardware, leave the Allen screw hand-tightened for now so you can later adjust the fitment angle for optimal accelerator pedal action. For such a small component, you wouldn’t think very many tools would be needed to install the part. However, there are several necessary tools required. You need: a 5/64-inch hex key; 3/8-, 7/16-, and 1/2-inch wrenches; wire cutters; a 1/4-inch drill bit; a hand drill; a Sharpie marker; and some masking tape. To correctly mount the accelerator pedal to the mount plate in the footbox, you must align the pedal with the accelerator cable hole. This allows the cable to come out and go in straight, so the cable doesn’t rub while going through the opening in its mounting point. Using the provided 1/4 x 1/4-inch screw and locknut from the pedal box hardware, install the top fastener first. The FFR Mk4 assembly manual says to install the top fastener while aligning it with the cable, marking and drilling the bottom attachment hole. Our second hole was already properly drilled. If you are building a different manufacturer’s kit, this may be a moot point. Also your FFR Mk4 may have both these holes already drilled, as ours was. Install the two fasteners and tighten them with the appropriate hand tools.
Step 18: Install Accelerator Pedal from Engine Bay
If you’re left-handed, as I am, the best place to install the go pedal is from inside the engine bay, especially if you need to drill the bottom attachment hole into the mounting plate.
Step 19:Cut Off Cable End and Thread Cable Through Top of Pedal
Cut the cylinder end off the throttle cable, using sharp wire cutters to prevent the cable from fraying. Remove the throttle cable from its sheath and thread it through the hole in the top of the accelerator pedal arm and through the retaining locknut, which is in the accelerator-cable componentsassembly plastic bag (for FFR Mk4 builders).
Step 20: Inspect Cable to Throttle Pedal
Everyone makes mistakes, and you’re not going to install every part correctly the first time. We realized we had made a mistake when we initially routed the throttle through the wrong side of the accelerator pedal hole. The round ball stopper should be on the passenger’s side of the hole as shown. Having the cable installed in this fashion allows the throttle cable to run smoothly into the sheath.
Step 21: Install Throttle Cable Sheath on Firewall Side
After threading the throttle cable into the throttle sheath from the inside of the pedal, tighten the cable sheath to the firewall with the supplied retaining nut. Place a piece of tape on the end of the throttle wire to prevent the wire/cable from retracting into the sheath.
Steering Shaft and Steering Rack
The installation of the steering shaft is rather easy. You need to be careful when you’re working with the set screws that are in the steering shaft adapter; they are quite small. After we installed the steering shaft, we covered the entire assembly with Sharkhide, which protects the metal for many years. We also like the satin finish that we get from using Sharkhide.
Putting the steering rack in place is a bit more of a challenge.
Project 3: Steering Shaft and Steering Rack Installation
Step 1: Inspect Steering Shaft and Installation Components
Unpack the steering shaft assembly and organize the tools for this installation. The steering bearings/ hardware, the steering shaft, and the manual steering rack and adapter are all going into your C-car chassis, which is an exciting prospect. This kit is taking shape. After patting yourself on the back, be ready with a 5/32-, 3/16-, and 5/16-inch hex key. You also need: 1/2-inch, 9/16-inch, and 10-mm wrenches; Sharpie marker; drill; 3/16-inch drill bit; Philips screwdriver; 15-mm deep socket; and a ratchet. Then remove the splined adapter from the end of the steering shaft. The first steering shaft procedure is to remove the splined adapter from the steering shaft by using the correct-size hex key. Replace this adapter with the new one that is supplied in the steering shaft assembly components and hand-tighten the set screws with the hex key so they don’t fall out.
Step 2: Loosely Mount Bearing to the Footbox Front
With the set screw toward the inside of the footbox, mount the flange bearing to the footbox front, making certain that both sides of the flange are on the front side of the footbox plate.
Step 3: Loosely Mount Top Pillow Block on Chassis
Be certain that the set screw is facing toward the rear of the car. Hand-tighten the fasteners that install the top pillow block to the chassis. You need some wiggle room to properly install the steering shaft, so just barely snug on those pillow block fasteners is fine for now.
Step 4: Install Steering Shaft into the Footbox
With both pillow blocks installed, you can do the fun part—slide the steering shaft into the footbox from the engine bay side through the low bearing. Beautiful!
Project 3A: Steering System Installation
Step 1: Inspect Steering Rack, Fasteners and Tools
To install the steering rack assembly, you require the manual steering rack assembly with the steering system hardware. The inner tie-rod extensions (two standing cylinders just below steering rack) are only used with power steering racks. If you’re installing a manual steering rack as we are, don’t use these. You also need the two tie-rod ends, four bushings, and the following tools: needle-nose pliers, 3/4-inch wrench, 3/4-inch socket, and a ratchet.
Step 2: Push Bushings and Sleeves into Mounting Bosses on Rack
The first order of business is to push the bushings and sleeves into the mounting bosses on the steering rack. You should be able to do this with your hands. If it’s really tight, dab a little white lithium grease on the rubber before pushing it home.
Step 3: Slide Steering Shaft onto Steering Rack
First, center the steering rack and align the steering shaft and adapter to the rack so you can easily push the rack onto the steering shaft.
Step 4: Bolt Steering Rack in Place
It’s easiest to bolt the steering rack into the frame by starting on the driver’s side. Then swing the passenger’s side into place and quickly fasten it. You can use a large Philips-head screwdriver to get the installation holes properly centered.
Step 5: Torque Steering Rack Fasteners
According to the FFR Mk4 assembly manual, torque the steering rack fasteners to 110 ft-lbs. If you’re building another manufacturer’s kit, be sure to torque the bolts to the amount specified in your build manual.
Step 6: Finish Tie-Rod Ends
The assembly manual specifies for the tie rod ends to be installed next. Before doing this, if your outer tie-rod ends are raw steel, paint the ends with primer and gloss-black Rust-Oleum before installing the grease fittings. To prevent rusting, allow the tie rod ends to dry before installation. With the gloss-black RustOleum all dry on the tie rods, it’s time to screw-in the grease fittings with an open-end wrench.
Step 7: Jam Nut and Outer Tie Rod on Inner Tie Rod
Upon screwing the tie-rod end and jam nut 1 to 2 inches down onto the steering-rack rod, you may realize the tie-rod end cannot mate with the steering arm. The tie rod end sticks out too far. You may need to shorten the steering-rack inner tie rods.
Step 8: Cut Off Tie-Rod Ends
Cut the tie-rod threads 3/4 inch shorter. Center the steering before doing any cutting. Temporarily place the steering wheel on the steering shaft and have the threepronged wheel with the prongs at 9 o’clock, 3 o’clock, and 6 o’clock, respectively, going clockwise. First, protect the threads of the tie rods with masking tape. Using WD-40 on the hacksaw blade makes the cutting go faster. Make sure you measure carefully—don’t cut off too much of the tie-rod threads, or you may be buying a new steering rack to replace the one you just ruined. Make sure the blade is perpendicular to the steering shaft so you get a straight cut.
Step 9: Torque Tie-Rod End Castle Nut on Passenger’s Side
With the correct-length tie rod, screw the jam nut and tie-rod end 1 to 2 inches onto the tie-rod threads. Then install the tie-rod end into the steering arm from below the steering arm on both the driver’s side and the passenger’s side. The FFR Mk4 assembly manual specifies that thread locker is used on all threads where jam nuts and adapter screws are not used. So before you screw down the castle nuts, use blue Loctite on the threads. Torque the castle nuts to 25 ft-lbs.
Step 10: Install the Cotter Pin
Installing the cotter pin is the last operation required to get the steering rack fully installed (before turning your attention to the upper steering shaft). Remember, a cotter pin goes on both sides. Use a hammer and needle-nose pliers to install the cotter pins.
Project 3B: Steering Shaft Mounting
Step 1: Inspect Upper Steering Shaft and Fasteners
You need the upper steering shaft, the steering system hardware, and the following tools to install the upper steering shaft: 5/32-, 3/16-, and 5/16-inch hex keys; 1/2-inch wrench; and rubber mallet.
Step 2: Attach Steering Shaft to Lower Shaft
Carefully slide the steering shaft through the upper bearing and start the smaller upper-steering shaft into the lower steering shaft. Turn the upper steering shaft so that the recessed bosses for the spring washers are facing up and place the spring washers into respective positions as shown. With the rubber mallet, gently tap the upper shaft down until the upper clip just disappears into the lower shaft. Tighten the upper and lower bearings, as well as the set screw on the upper shaft. Your steering should now be spot-on.
Written by D. Brian Smith and Posted with Permission of CarTechBooks