Pedal box / brake MC fitment issue

[erachner]

Hi all,

I've run into a baffling & frustrating fitment issue mating my 2007 WRX pedal box to the brake master cylinder. As per the instructions, I mounted the pedal box and used the firewall panel guide holes to drill out the pedal box as shown here:

PXL_20240616_000015169.MP.jpg

But despite the fact that the holes are, as best I can tell, in the correct position with respect to the brake MC, when I go 'round to the inside of the firewall, I find that the holes are too close to the central structure of the pedal box to align the mounting bolts correctly, much less fit nuts around the mounting bolts:

PXL_20240616_000156048.MP.jpgPXL_20240616_000116178.jpg

I searched the forums a bit but didn't see any posts about this. Did I blunder or am I missing an obvious mistake here? For the moment, I'm assuming my solution will be to modify (read: cut/grind) the pedal box to make enough room to thread the bolts through, probably from the inside of the cockpit going outwards, and thread the nuts on the MC side forward of the firewall.

But I'm open to any suggestions folks might have. Much thanks!

[Bicyclops]

Howdy,

I can't find any detail pix of when I did this but I do seem to remember dealing with some alignment issues. This is probably not going to be the last place where you'll have to "make it fit". I've ground down one side of a hex bolt and/or washer on numerous occasions and enlarged/slotted holes too.

One piece of advice I'd give you at this juncture is to drill a hole higher up the brake pedal for where the yoke attaches for better leverage. FFR has you drilling such a hole, but it's not high enough for unboosted brakes. In the FFR hole, I had so-so braking action while really standing on the pedal. The hole I drilled higher than that is much better, but will be very difficult to accomplish after it's mounted up and the dash is in etc.

Ed

[RPGs818SNA]

That’s a FFR design flaw. I did just like you said, ground down one side of a hex head bolt and put the nut on the outside. That worked fine.
Happy building,
RPG

[lpmagruder]

I think I ended up using a SHCS and put that bolt in from the other side. It's been a while though.

[erachner]

One piece of advice I'd give you at this juncture is to drill a hole higher up the brake pedal for where the yoke attaches for better leverage. FFR has you drilling such a hole, but it's not high enough for unboosted brakes. In the FFR hole, I had so-so braking action while really standing on the pedal. The hole I drilled higher than that is much better, but will be very difficult to accomplish after it's mounted up and the dash is in etc.

Hi Ed,

Do you happen to recall roughly how much higher you placed that hole to get the improved brake feel? The most recent revision of the assembly manual suggestions 1/2" upwards of the stock hole. How much higher would you suggest? Like one full inch above the stock hole, or...?

Thanks

Eric

[Bicyclops]

Howdy Eric,

I'll look for a picture. I had drilled in the FFR location and then read about bad pedal feel from others. It might be another 1/2", not sure tonight. I remember thinking that I wanted to get at least 2 clevis pin diameters away. I do know that when I got the push rod installed, I was struck by how much angle there is on it. I was afraid it might bind, but that doesn't seem to be a problem. The end of the rod is rounded and fits in a cup in the master cylinder so it does push it even if it is at an angle. It's not an easy hole to drill, if I remember right. I think I used a long drill bit and might even have drilled through the pedal bracket to get there.

I've also got very large calipers, Cadillac Brembo, all around and turned down the proportioning valve 1 turn on the rears. FFR has larger brakes up front and you have to turn those down which makes for more pedal pressure to get the car stopped. Without power assist, you need every advantage you can get.

Ed