I recently came upon the issue of installing the hydroboost and figuring out how I wanted to set up the pedal assembly. As with most people I really wanted to use the 04 Cobra pedal assembly for several reasons:
A. The clutch/brake pedals are much bigger than the Fox ones, and spaced farther apart as well.
B. The spacers that go between the pedals and the firewall are metal (sturdier) on the Cobra set-up, versus cheap plastic on the Fox ones. (SEE PICTURE)
C. The appearance of the Cobra pedals is much nicer.
D. The brake pedal doesn't have to be modified to connect to the hydroboost plunger.
My issue is that I'm keeping the Fox dash, so I need to have the mounts in place for the dash and steering column. Once I got the pedal assemblies side by side, I knew that I couldn't just bolt in the Cobra assembly because it didn't have the brackets to bolt in the Fox steering column. The placement of the pedals and sensors was the same, as well as the upper mounting hole. I thought about swapping the pedals from the Cobra to the Fox bracket, but the placement of the pedals wouldn't work because the come down at a different angle on the Cobra set-up, versus straight down on the Fox. So I consigned myself to having to rig up the Fox pedals to work with the hydroboost, and I set about building a spacer out of an aluminum plate to replace the cheap plastic spacers. When I was almost done with that set-up I was comparing the 2 assemblies side by side, and came up with an idea to make the Cobra assembly work after all, the steps of which I will detail here.
These pictures show the comparison of the spacers, and the alignment of the brake pedal to the hydroboost plunger when the fox bracket is finally bolted to the hydroboost.
The first thing that you want to do is mount the Cobra assembly in the car and bore out the holes in the firewall to match the holes in the pedal assembly spacers, and trim out the large middle hole where the center of the hydroboost comes through. You can pick up a decent inexpensive set of transfer punches Harbor Freight tools if there's one near you. Most of the holes will be 5/16 or 15/32.
What I keyed in on that made me realize that I could make a hybrid pedal assembly was that the hole for the upper mounting bolt, that's in the top of the bracket, is in the same location on both brackets. So I figured that if I trim off the excess parts of the Fox bracket, I could align those holes with each other, and weld the 2 brackets together. The pictures below show the lines that I made to mark the parts of the Fox bracket to cut off.
I did the cutting with a cut off wheel on a die grinder, and after the initial cuts I had to do a little trimming to get enough material off the Fox bracket to be able to get it inside of the Cobra bracket so that the holes would line up.
I then drilled 5 small holes around the alignment hole on the Fox bracket. Two of these were so that I could mock up the set-up with rivets before welding to make sure that everything lined up. One place to make sure to line up is the bracket with the forward mounting studs for the steering column in order to verify that it's bolt holes will line up. I then drilled out the rivets and the holes were used for the initial spot welds. Make sure to put a bead along the top where the brackets meet because that's going to be a stress point as you put weight downward on the steering wheel. You will also note in two of the pictures that I added a couple small pieces of metal in to add extra bracing.
Once the welding was done, I bolted the assembly and hydroboost in, and everything lined up perfectly. Now I have the best of both worlds with the Cobra pedals underneath a Fox dash/steering wheel. I bolted up the steering linkage and connected the brake pedal, and everything works perfectly.