Fire wall brake reservour

Hey Guys
I have fought tooth and nail a low brake peddle in my 1934 ford every since i finished it. I have exhausted all that I know what to do to improve it. From different master cyl (bore size),pedal ratio, calipers,etc, etc. One more, does a fire wall reservour help this issue of the under floor master cyl?

Thanks

 

Are you using 2 psi residual pressure valves for disc and 10 psi residual pressure valves for drums?

 

The height of the reservoir will not affect the pedal travel.

 

More info ?? Disk/drum? single /dual mc? Improper drum shoe adjustment,loose front wheel bearings or warped rotor. Flex in MC or pedal mount.

 

I suspect an adjustment problem. Especially if it is 4w drum brakes. It acts just like air in the lines because it can be pumped up.

 

Whats your exact setup? Its hard to diagnose brake problems without eyes and hands on.
Start with what master, what size lines, single or dual, are you getting full travel(front and back), do you have a return spring on th pedal, what brakes (front and rear) does your brake lines pass near a exhaust. Get where we are going.

 

I have four wheel disc. Using gm metric brake calipers with 11" rotors front and rear. I ran 3/16 dia line to both ends. Plumbed out of m/c to 2lb residuals, one for front and one for rear, then into gm proportion valve. Straight out to rear brakes and split line at rear to each wheel. There is two outlet on proportion valve for front. I plumbed to each wheel separate from there. I have 5 1/2 to 1 pedal ratio. I am running a 1 1/8" bore dual master cylinder with single booster. Have tried 7/8" bore, and 1" bore. Ended up going back to 1 1/8 bore that I got from ECI. I hope this is clear enough. Oh lines not close to exhaust.

Again thanks guys for all the helps

 

Issue has been done to death, do a search for "quick take up calipers" or "low drag calipers"

 

http://www.mpbrakes.com/technical-support/troubleshooting-disc-07.cfm

 

Would a GM quick take-up M/C be appropriate for old, large dia. drum brakes, since it would accommodate more slack in the shoe adjustment?

 

Would you suggest a quick take up m/c going under floor?

 

Either that or change the calipers to standard operation units.

I would just get the shoes arched properly and adjust the shoes than open that can of worms.

 

First off you have to many valves in the system. Get rid of the risidual valves (wrong application) take out the proportioning valve ( shouldnt be needed with the GM proportioning valve). That jumped right out to me.
Did you bench bleed the master?

 

Hi is correct on the too many valves, especially if you are running disc on all 4 corners.

a few other questions:

1] What size is your booster? if it is a 7" single there is part of the issue.

2] What type of rear calipers did you use? If you did not ratchet up the e-brakes first, you may have a sizable gap to be made up hydraulically - taking up quite a bit of "swing" before you begin to stop.

The quick takeup "issue" is a red herring: the piston in the caliper only retracts about 0.020" at most.

 

Keep in mind m/c is under floor. this stuff was sold to me by ECI Oh and i bench bleed m/c

 

Don't have caddy brakes anymore. Won't have anymore. And they were set up right several times till I filed them. Hardest caliper to get air bleed out of. They are to busy inside of them. Have 1978 to 8? malibu calipers on back same as front. Bolted right in to same caddy bracket and used same rotors. oh 7" booster with 17" of vacuum.

 

Take a look at this site.Lots of good info...http://www.hot-rod.com.au/builder/brakes.html

 

Don't forget to check end play in the pushrod.

 

Well Guys this is sort of embarassing but got my problem solved. Got a full pedal as well as brakes now. I had grabbed the wrong m/c off the shelf and put on the car. I had put a 7/8 bore m/c on the car. Got the right, 1 1/8 bore m/c and put it on the car and guess what? It fixed the problem of a low peddle. I am sorry if I wasted you all's time.Thanks guys for all of your support.

 

The issue that concerns me here is that may be masking the problem - can you lock up the wheels? A 1-1/8" booster takes a good sized booster to use, I do not think a 7" single booster will provide enough pressure.

As stated before - low pedal is indicative of air in the lines, not a master size issue.

 

You mention buying parts from ECI. I suggest you call them and go over your system. Ralph Lisena, the owner, is one of the best brake men in the business. If you haven't consulted with him about your system your missing the boat. It sounds like you have a piecmeal system and he can straighten out out on the correct combination.

Frank

 

Scarebird: It will lock them up but takes a lot of foot pressure. No air in lines. You got a point about booster but no room. Volume does make a differance. Big bore will allow you to push more volume. Small bore allows you to push more pressure. This tells me I have to pick the happy medium. Am I right? I am open for suggestions. But brake peddle/master cylinder is not bolted in. This would be a major job to change this.

fab32: Yes I do have one of their front ends no complaints at all. Think I will Call them. Thanks

 

Can you either find a 1&1/16 MC or increase your pedal ratio by 1" ? A 1/16 bore diff in a MC makes a noticable diff. Do a little math and figgure out the % area change from 1&1/8 down to a1/16 smaller.