Brake hoses causing spongy pedal?

Correct. However, velocity has nothing to do with volume. The only volumetric adjustments you can make are in the relationship between the master cyl and the wheel cyl.

Sounds like you might have found something you can try with your connections anyway.

good luck

Pete

 

He has the same rear (40) but has f-1 front brakes. I understand about the displacement but doesn't going to a smaller line push the fuid faster? If that was the case maybe it will give me more pedal on the first push. Maybe I'm wrong but we'll find out. My buddy ran 3/16 line all the way and his pedal is like a rock.

 

Yes, it will push the fluid faster...same as if you have a 3/4" garden hose and you adapt it down to a 1/2" hose. You might get the same amount of water out of the end but in order to get it the water will travel faster through the 1/2" hose. You cannot increase the volume of fluid moved in a sealed system by changing the size of the tube.

If one push on your pedal displaces 1 cubic inch of fluid, it will still be one cubic inch of fluid at the other end. It won't get any bigger by pushing it faster through a smaller tube.

Pete

 

Just a thought, you did mention that you were running residual pressure valves. I hope they are the 10# units for drum brakes. You did not mention if the master cylinder was mounted below the wheel cylinder heights but sounds like it is. The other thought, is the 68 Camero master cylinder from a drum/drum car and does it still have the factory residual valves in it as well. It should be punctured or removed if you are using the inline type or remove the inline valves and see if anything changes.

 

Is is lower than the brakes. They are 10 pound units but I never would have thought about the valves in the master. It is a drum/drum master, would it have factory valves in it?

 

Makes no difference, one valve or 10 valves, it still functions the same. Are they Wilwood valves inline?

 

Your pedal ratio is probably too high. I have run into the same spongy problem several times and a ratio change always solved it. Do a search on pedal ratios and lower the ratio.

 

try this, take your 10 lb check valve, take it apart, there is a spring like a ball point pen and a little piece of rubber inside there. Take it out, put the valve back together without anything inside of it, bleed it at that fitting, and then see if you have brakes. I have had this problem 3 times in the past year. If your pedal stays firm, leave the stuff out of it, that means there is one inside the master cylinder, if the pedal does not stay firm, replace it. Takes 5 min. to check. Good luck. Terry

 

This thing has me so stumped. The bore on the 68 camaro master is 1 inch, 1940 ford is 1 inch or 1 and 1/16. The pedal is pushing the piston all the way in. I cannot see a ratio problem here. I swapped the lines to the correct reservoirs and still nothing. Why don't I have any pedal??????????????? My pressure valves are from speedway, everything is new. Bout ready to throw this F@*ker out!!

 

Post some pictures, maybe someone can spot something.

 

Changed the front over to all 3/16 line and you guys were right, nothing changed. I got in the truck and noticed that the brake lights aren't coming on until the second pump (in line switch) so there is no pressure in the system on the first pump. Then, I was reading an old rod n custom and they had a section in there on brakes. It says you cannot have a loop that goes up and comes back down above the level of the master cylinder or it will hold air. My rear line goes up and over my banjo rear and it is above my master. Could this be the problem??

 

Yep It is posiable.

 

Line size has ABSOLUTELY NOTHING to do with your problem. I know it is a hard concept to wrap your head around but changing the lines back and forth is just complicating the problem you have here.

Soft pedal can be an incorrect pedal ratio. Non-***isted brakes are usually around 7:1 and you should be able to push your master cylinder piston into the bore about 1 1/4" durring a full pedal stroke. This would mean you need over8" of pedal travel available. If you do not have this, you need it.

 

I can push it in about 1 1/4 and there is about 9 inches of travel.

 

ok then, move on to the next issue.

Your master cylinder, remove the lines from the cylinder and install some plugs and see if the master cylinder locks up. This is an alternate method of bleeding the master cylinder. It also exposes the condition of said cylinder, it should lock up solid.

 

so how goes the battle?, do you have good brakes yet or what?

 

Just a thought, didn't see it mentioned: Did you bench-bleed the master? (small lines running into the fill area on top? You'd be surprised to see how many little air bubbles are in that *****! Must do!