I wonder if You can give me some ideas about a problem i have. I channeled my -31 pu body 6" and want to keep the "original" brakepedal position i have. -46 pedals in a homemade frame. I Only want to rebuild the pushrods for main cylinder and clutch. Not relocate the pedals. The system has new wheel cylinders, new lines, new early Mustang main cylinder with dual jars. No vacum booster. -46 ford brakes in front and 8" rear. I have never tested this system filled up before the channeling and now i wonder how far can i expect the brake pedal to sink when i step on it? What is a normal distance for Your brakepedal, with simular systems?
Howdy Thor- I would expect the pedal to start "feeling" like brakes at a little over 1" travel.it really depends on the length of the lever at the bottom of the stock pedal. if you have the stock short lever there it will give you more travel than I mentioned. the problem is that it has too much pedal ratio as it sits. it will work- but you will have extra travel in pedal at least and may have to 'pump" em to get a firm pedal. I would look into increasing the length of the "bottom lever' on pedal.they are a forging so it can be welded sucessfully.
Another thing to keep in mind - you will need residual pressure valves to the front and rear brakes if your master (main) cylinder is below the level of the wheel cylinders
Thanks choprods and paul2748! I have some additional questions though. I realize that it does not matter how far my brake pedal rubber goes, in my case 2-3/8", if the stock short lever does not push the main cylinder rod enough deep, but i pressed the rod to the bottom and it needed 29/32"(dry). In my setup right now the main cylinder push rod only goes 15/32" before the brake pedal arm hits the edge of the engine block. Can i live with that maybe? How far must the rod travel to put the brake system pressurized, do You think? Second, does not the early dual main cylinder for drum-drum brakes have an internal residual valve? Maybe i need them anyway, because of the low location? If i use them, do i need to change the fluid pressure brakelight contact i use now, to a mechanical one? How about shortening the pedals 2"! That would be much easier then making the short lever longer. Will the changed ratio increase the needed power for braking and clutching so much that the traveling won´t be a pleasure? I have stong legs but my wife is a tiny one and i need her to drive sometimes when i have had a beer...
If you are running drum-drum leave internal residual valve leave in first, disc brake require alot hyd fluid thats why they are takin out, try not dry check it to much cause it can damage master cylinder. A check valve is put in when firewall mastercylinder are relocated below floor boards to prevent fluids from backing into master cylinder. Showed have little preload on shoes. Many aftermarket hotrod brake suppliers have FAQ sections that can explain alot of brake problems on thier sites. And free for viewing
[ QUOTE ] Second, does not the early dual main cylinder for drum-drum brakes have an internal residual valve? Maybe i need them anyway, because of the low location? If i use them, do i need to change the fluid pressure brakelight contact i use now, to a mechanical one? [/ QUOTE ] I'm using a fluid pressure brakelight switch, works fine with my all drum setup which has residual valves. It's a standard pressure switch, there are low pressure actuated switches but I can't see why you would use them. When applying your brakes so much pressure is built up a standard switch seems to work fine. If it were me, I would get the car running with the stock brake pedal length first. It's easier to shorten later, but not so easy to add back on length later. I would try to eliminate the interference with the block somehow, there would be more piece of mind if you knew you had more "Insurance" built into the system.
Yea, thats probably the most effective way to go. Assamble the brakes, fill up the system, bleed it and step on the brake, before i get carried away. I´ll do that! And i order the 10Lb residuals. They can rest on the bench for a while. Thanks guys. Btw, found this pretty fast: http://www.mpbrakes.com/mpfaqmasters.htm
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