Help with Brakes, Wrong MC?

[JLMounce]

Over the last week I went through my entire brake system on my 1969 Firebird. The system has functioned well for many years now. It was never what I would call fantastic, but you could drive it hard and the brakes let you do what you wanted with the car. It was a basic setup consisting of factory style 11" rotors at all 4 corners, OE D52 calipers in the front and OE D154 calipers in the rear. Everything had gotten a good bit of rust on it, so I opted for the Wilwood D52 and D154 replacement calipers.

After wiring wheeling the discs and coating the hats for looks, I installed the new calipers and bled the system using a vacuum bleeder.

I completed the bedding procedure and I'm left pretty disappointed with the brake performance afterwards. I have a firm pedal with positive feedback and under normal braking the car stops as expect. Under hard or near panic braking, there's just not much more there. As the car starts to slow rapidly, I reach the limit of the brake pedal's travel and I'm unable to get to the point where locking the wheels is possible.

Here's a rundown of the entire system.

9" single diaphram booster
Engine makes 13" of vacuum at idle
1" bore MC
2" dual piston D52's in the front
1.12" dual piston D154's in the rear
Clevis attached to the bottom hole in the pedal. I believe Camaro/Firebird factory lower hole is 3.8:1 ratio

The previous calipers had the 2.75" pistons in the front and 2" pistons in the rear. 5.94 in^2 for the front and 3.14 in^2 in the rear.



New calipers are 6.28 in^2 in the front and 1.98 in^2 in the rear.

The way the pedal acts, it almost has me thinking the MC is undersized for caliper area, but I wouldn't think this small amount of increase in the front, and reduction in the rear would be that noticeable. The brakes are not hard to operate, so a little more pedal effort wouldn't be a deal breaker is a 1 1/8" MC would give me the travel necessary for proper function again.

I've thought about moving the clevis up to the top hole in the pedal as well, but am fearful that with the booster in place, it'll be too twitchy.

What's everyone's thoughts on this? I'm going to bleed the system another time tonight after it's been driven at sat for a bit to see if I just don't have a small amount of air, but I'm pretty positive it's bled properly.

Thanks in advance!