Brake hoses causing spongy pedal?

I am trying to get my truck on the road again after my ****** rebuild and have some brake issues. I have a suicide front end. Frame is under my axle so I ran brake hoses down to the axle and hard lined them to a fitting in the center. I then have another brake hose there going to the frame so I have a total of three. This truck has been bled and bled, master cylander changed and still a spongy pedal. This weekend we got out a set of vise grips and clamped on the one hose that leads to the axle and whammo, hard firm pedal. Do I have too much flex in my brake system because of the three hoses? I cannot see the hose ballooning and they are all new. What do you think?

 

the part of the system that you clamped off either has air in it or the brakes are not adjusted or working correct.

 

The more rubber hose you use the softer or spongier the brakes will feel.

 

I have had problems with '' SPONGE PEDAL'' from just ONE section of brake line and NO you can't see it balloon out.....

Also like 440roadrunner advised its not cool to use vise grips on any soft brake line .

It WILL damage it

 

Baloney.

 

Sounds to me like you might need to rebuild a wheel cylinder, or maybe the master cylinder even though you say it is new. Either could cause spongey feel without a huge brake fluid leak.

 

i'm having the same trouble i think, but its a stock 29 chrysler, i think the lines must be swelling, next time my buddy comes by i'm putting my digital calipers on the hoses just to see what happens.

 

If those stock rubber lines are new if they were swelling King Kong must be stepping on that brake pedal. Hell, if your drums are thin THEY will be swelling and end up egg-shaped to boot...don't ask me how I know this.

 

Another possibility is if the drums were trued and the lining were NOT arced to match you may be bending the brake shoes a little - that feels spongy - and don't ask how I know this.

 

Ok, the wheel cylinders are new, new master, new lines, new hoses, new shoes. Drums have been turned but are still within spec according to old ford manuals. The vise grip was put on with a rag between the teeth so don' worry about that. This is not a bleeding issue, trust me. It has been bled and all air is out.

 

I understand that some reproduction-type early Ford brake hoses are manufactured in Argentina and ARE NOT DOT-approved for use in this country. This could be the problem if all else seems okay.

Hope this helps.

 

Sometimes new parts are defective. Try switching out the hose you clamped off. I had to replace a set of new hoses on my apache because of defective parts.

 

440 roadrunner has suggested a way that I feel makes a lot of sense. That will completely eliminate or verify the balooning hose question.

 

The hoses coming from the wheel cylinders are for a 40 ford from Sacramento Vintage Ford. The one that comes off the center of the axle to the frame is a store bought hose and it says made in Japan on it. It is much more pliable than the ones from Sacramento, not as stiff. Think I will change it out and see what happens.

 

if you have lower adjusting pins on your brake ***embly i would check to see if you have them adjusted correctly..

 

Front brakes are from a 48 so no lower adjustment. The shoes are backed all the way out to the drum at the moment to see if that changed anything and it didn't. I find it hard to imagine I have a defective new hose but could be I guess.

 

Ok guys, what about this. I am running a 68 camaro master, 3/16 line coming out to the residual pressure valves. This goes to the brake hoses. Then I have 1/4 line from the hose going to the wheel cylinders because ford used bigger lines back in the 40's. Is this the sorce of my problem???? What about getting adapters and making all the hard lines 3/16? I think that the jump in line is causing the problem. What do you think?

 

are you thinking that because of the larger line the fluid could be compressing a little more, if so then nope, if the line was 1" it wouldnt make any difference either, it would have to be air or a hose expanding, i dont really how you have the three front hoses hooked up but you could try replaceing the hose with steel line just to try, do one at a time, if when you were bleeding the fluid only came out kinda slowly then air can get t****d in a high spot leaving the fluid to p*** without ever moving the air bubble, the fluid should shoot out of the bleed screw like a jet.

 

Just a thought....Are all your bleeders at the the most upper location for bleeding? (air will always gather at the top of a caliper of wheel cylinder or such.) Also I have ran into brake linings that are just plain soft/poor stopping power to the point of unsafe. This I have seen twice on disc...but just a thought.

 

My axle is over my frame (underslung). i could not find hoses long enough to reach the frame so my solution was this. Run a hose from the wheel cylinders (48 ford brakes) to tabs welded to the axle. 1/4 Hard line from there to a T in the center of the axle. From there there is another hose going to the frame. I have 3/16 line coming out of the master through residual pressure valves to the hoses. Back is just like the front but hard lines all the way to the wheel cylinders (40 ford brakes). Just after the hoses I bumped the lines up to 1/4 to screw into the wheel cylinders. Just wondering if the change in line size is causing a problem. Everything is new and this system should work but 2 pumps makes the pedal hard, not one. I hate brakes.

 

two pumps sounds like your brakes are not adjusted enough, but you say you have them adjusted out tight allready. so after two pumps no more spongy?

 

No more after 2 pumps, hard as a rock. One pump, pedal goes down almost all the way to the floor. Is my master not pushing enough to move the wheel cylinders?

 

sound more like your shoes are moving too far, or your master is no good, if it gets hard then we can rule out air, i saw your front end in the other thread.

 

master is new, old one was doing the same thing so I thought it was that and bought a new one but same problem. Shoes at the moment are backed agaisnt the drums, almost locking the wheels up but just enough to turn them. This is getting frustrating.

 

That is why I was thinking that running all 3/16 line might fix it because it pushes more fluid than 1/4 line. I thought they were working ok just needed to be bled more but maybe it's been wrong since the start. What is a good dual master to use with 40 ford brakes???? Only reason is because I want the comfort of not having any brakes if I blow a line.

 

Line diameter will not influence the volume of fluid you move. Only the diameter or stroke of the MC piston will change that. It sounds a lot like adjustment but you seem to be ruling that out. Sure you can't crank the shoes out any further? No? Then the MC volume sounds like a reasonable line to pursue.

Oh yeah, have you adjusted the lower adjusters on the rear?

Pete

 

What is the stock piston bore of a 40 MC? I wonder if the 68 camaro MC I have is too small for the stock 40 wheel cylinders. the pedal pushes the piston in all the way so the pedal adjustment is right on. I may be wrong but when 3/16 line goes to 1/4 line, there is a jump in volume. If it was all 3/16, it would be pushing more because there is less fluid to push correct??

 

once the lines are full of fluid then it wouldnt matter what size they were, one thing is with a duel master you get fluid from two chambers while with a single you only have one chamber, so how do you have your master hooked up, are the front brakes hooked up to the outlet away from the mounting tabs?

 

I don't think that brake fluid can compress.


Check to see if there is an adjustment between the pedal ***embly and the master cylinder rod. I thought that my brakes were spongy and bled them all this weekend to no avail. my pedal would almost go to the floor before the brakes started working. I adjusted the linkage bet. pedal and M/C and now it is a nice high pedal with good brake feel. I could get it higher yet once I back off the shoes a bit.

Scott

 

My thought is that with 3/16 line, I would be pushing fluid faster than with 1/4 line. I measured my master, it has a 1 inch bore and my buddy's 40 master is also a 1 inch bore so that throws the wrong piston diameter out the window. Here is a mistake I noticed. I have the master hooked up backwards compared to where it would be on the 68 camaro, it is bolted with a conversion plate to my 40 pedals. I am running the lines to the wrong places. The rear on the master is now the front and vise versa. This could be causing a problem also. What I am going to do is swap the lines and go to all 3/16 line. This thing has to push enough fluid to make the 40 wheels cylinders work.