what a nightmare!!!! I took on this project for a friend, and I just CAN NOT win with this thing. it's a Scarebird disc conversion kit, nice kit, easy install. Uses 95 Crown Vic hat rotors on the original hubs, and 80 Electra calipers. I originally ordered a complete pedal kit from Butch's, but the owner changed his mind on a trans swap, so I fabbed a pedal setup and used the master and booster from Butch's. The master is 1" bore, and 1.25" stroke. It has the machined slip in plunger adapter, it'll work either shallow or deep plunger. the booster is an aftermarket 7" dual diaphragm with a short plunger Wilwood 2psi residual to the front, and Wilwood 10 psi to the rear. the pedal is the original pedal arm, pivoting on the original shaft, with a 5/8 rod running through the gutted original master cylinder, back to fabricated brackets that carry the new booster and master. The original pedal has a ratio of 5 to 1. stroke is 1" so here's the issue---how have you guys corrected a stroke mismatch like this one? The only thing I can think of is to fabricate a ratio corrector that increases the stroke at the master cylinder so it bottoms before the pedal hits the floor. Sort of a stub pedal between the original pedal and the booster, with like 2 to 1 ratio. and, to answer some of the most common questions: YES, I...... .....am sure the system is devoid of air .....mounted the calipers right side up and on the correct sides of the car .....adjusted the rear drums BEFORE bleeding .....adjusted the freeplay out of the pedal before bleeding .....double checked the booster plunger depth before installing the master
Hi, Call Butch up, that guy knows everything! He should be able to help you. The phone number for Butch's Cool Stuff is 937-405-3399. Good luck!!! I heard that their new website launches sometime in the next few weeks!
I cannot offer much, other than my own experience. I do NOT like that booster AT ALL!! I feel it simply does not work, period, full stop. That said, If t'were my car, I'd seriously look into a hydroboost unit. Slightly hosi-er, but the bloody things work. Rolling back a lot, I have always had the best luck with brakes if I: A) Match the master/booster to the front brakes, meaning from the same car. B) Use the pedal and linkage from a donor car, complete. C) Get "underfloor master" out of my mind. Accept the slightly ugly firewall unit as a sop to really good brakes. D) Juggle rear cylinder bore sizes until the car is either balanced or has slight tendency to lock the rear, then I might use an adjustable proportioning valve to fine tune. Hope this helps, Cosmo
You might talk with Ralph at ECI. As I recall the original Mopar brake leverage was done because they had 2 wheel cylinders in each front wheel so there is a lot of leverage to give enough fluid volume. I went with his pedal set up and it worked good.
to expand on my situation--- currently the car is completely stock EXCEPT the brakes. Stock Hemi, Fluid drive, factory 6 volt generator driving the power steering, stock interior, stock paint. the owner isn't an old car guy, but he likes the car, and wants to drive it regularly. He drove it before and wasn't comfortable with the stopping power, and felt that there was something wrong with either the engine or the transmission. We talked about doing the brakes, a 12v. conversion or a full rewire, and replacing the Fluid Drive with a 727. I drove the car before I tore it apart, and I thought it was just fine, but then, I LIKE the "old car-ness" of old cars. Turns out the trans is fine, he just didn't know how to drive it. That's when he decided to do just the brakes to begin with (again, I would have left them). and that's where the SNAFU came in. I couln't use the pedal assembly I got from Butch, because I had to keep the original clutch pedal, which pivots off the same shaft as the brake pedal, and is carried by the master cylinder casting. there's abolutely NO chance of changing this to a firewall mounted system. I could change the booster and master to match the calipers, but it's VERY likely that I'd still have a stroke/ratio issue, so I might as well fix it with all the stuff I already have.
A picture of the brake pedal would help, but why can't you just reposition the pushrod on the pedal to change the ratio and thus the stroke. As an example (since we don't know the exact numbers) say the pushrod was 1" from the pedal pivot and the pedal itself was 6" from the pivot. Pushrod moves roughly 1/6 as much as the pedal. If you want more stroke in the pushrod for the same pedal stroke, move the pushrod further from the pivot point. If the pushrod were 1.5" from the pivot in this example, the pushrod would move 1.5/6 (or 1/4) as much as the pedal. Obviously this increases pedal force required for the same braking force, but you can't have everything.
I forgot to address this aspect, as it WOULD be the easiest, but the ear on the pedal that pushes the rod has no extra material to reposition the hole, and the trans crossmember is directly below the original master cylinder, so there's noplace to run the rod, EXCEPT through the old M/C bore.
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