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Pedals to the Metal
How to build a pedal box assembly
Created by Dan BurrillA number of street rod companies offer fiberglass bodies and kits at various levels of completion. Many of the bare-bones basic kits don't come with all the parts needed to complete the car. That's where swap meets, salvage yards and want ads come in. For many of us, collecting the parts is half the fun. Of course, a bit of elbow grease is necessary as well, along with some custom fabrication. One of the more common projects involves making and installing a box for the throttle, brake and clutch pedals.
A pedal box is fairly easy to construct and is universal, so it can be used with most any street rod or hot rod project. And it will work for either floor- or top-mounted pedals.
The three main parts of this project are the box, the arms and the pedals. Several different types of pedals can be fitted to the arms. We used the old AC Cars style of pedals (found on the original Shelby Cobra) because they are tall and narrow and don't take up a lot of room in a small foot well.
Taking Measure
The first step in building a working pedal box is measuring the size of the foot well area and deciding on whether to use floor- or top-mounted (hanging) pedals. In this particular project we used a B&B chassis that allowed us to show both installations.
The project is not too difficult, and with the help of a machine shop, it can be done at a reasonable cost in a short amount of time. Although the floor-mounted pedals may have a more original look for certain types of project cars (such as Cobra replicas), with the hanging pedals there is a lot more foot room, especially if the kit features a dropped floor such as this one does. Whichever type you choose, just be sure to measure twice before cutting, because there's not a whole lot of room for error.
Resources
Finish Line, Inc., 3593 S.W. 173rd Terrace, Miramar, FL 33028, 888/438-9113 www.cobraaccessories.com
B&B Manufacturing, 9940 Raccoon Rd., Granby, MO 64844, 417/472-3547 www.cobracountry.com/bbmfg.html
Boffin Motorsports, 12975 S.W. Watkins Ave., Tigard, OR 97223, 503/624-2659
Step 1
The backbone of our pedal box is a 2x4-inch piece of channel, 12 inches long, with a 4x4-inch square plate, 1/4-inch thick, welded to one end. This plate fits against the firewall, forms the front end of the pedal box, and serves as the firewall mount and the mount point for the brake master cylinder.
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Step 2
Approximately five inches from the front end of the pedal box, drill a 1/2-inch hole where the supporting bolt is inserted to hold the pedal arms in place.
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Step 3
The pedal arms are fabricated from 1/4-inch steel plate. Check the foot-box measurement and draw out the design on heavy cardboard for a cutting template. Any welding shop can cut the steel plate. A 7/8-inch hole is drilled at the top of the pedal arm for the 4-inch long support pipe. A 3/8-inch hole is drilled in one arm for connecting the brake master cylinder's push rod. At the very end of the pedal arm a 1/4-inch hole is drilled to attach the pedals.
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Step 4
The 4-inch long (5/8-inch inside diameter) pipe is inserted through the top hole and welded in place. The brake pedal arm is centered on the pipe and the clutch pedal arm is offset to allow for pedal clearance. Oil-lite brass bushings (1/2-inch inside diameter, 5/8-inch outside diameter) are inserted in each end of the pipes. (Oil lite bushings are made of oil-impregnated bronze and practically never need to be replaced.)
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Step 5
Here we have fitted the 5/8th-inch plywood floor on top of the car's frame rails to check for clearance. Note the two slotted holes cut in the plywood for the upright, floor-mounted swing arms.
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Step 6
The brake pedal arm is mounted in the center of the pedal box and the clutch pedal arm is mounted on the outside of the box. This photo shows the clutch pedal arm mounted on the right side of the box for use on the hanging pedal assembly. For the floor-mounted, upright assembly, the clutch pedal arm must be moved to the other side of the box.
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Step 7
The aluminum AC pedals supplied by Finish Line must be slotted and drilled before they can be mounted to the pedal arms. You may need to fabricate a wooden cradle to hold the pedals in the vise while milling out the slot. Shown here is the original pedal (top) and one with the slot milled (bottom).
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Step 8
After drilling a hole through the slot, this is how the pedals attach to the pedal arms.
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Step 9
The completed pedal box is positioned in the car and checked for fit. Remember to allow room for the gas pedal. The chassis from B&B Manufacturing features an dropped floor made of 18-gauge steel, making an upright pedal assembly fairly easy to install. With the pedal box in position, a 2x4-inch angle brace is used for support. With the plywood floor in place, this looks very much like the original car.
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Step 10
For the hanging (top mount) pedal box installation, we first make sure the clutch pedal is mounted on the correct side. Next the box is clamped into position with the front piece flat against the firewall. The rear of the pedal box is checked for fit and clamped to the underside of the cowl hoop. Don't forget to allow room for the gas pedal.
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Step 11
At this point, mark and drill the two mounting bolt holes and the larger center hole through the firewall. After checking for fit, use self-tapping bolts to attach the rear mount to the underside of the cowl hoop.
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Step 12
Now the brake master cylinder is ready to be installed on the engine side of the foot well.
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