Brake problem, need to fix ASAP for the roundup! FIXED, post #22

[chris]

Long story short, I took the front axle out to work on it and found a rubber brake line leaking. Figured I would replace both lines with Braided lines so I ordered 2 lines from Wildhorses for the 76-77 disc axle. I have a 71 axle that got the drum to disk conversion. The new Brake lines had larger hardline connections so I put adapters on and the caliper end was 1/16 to small for the old banjo bolt so I drilled it out. Used new copper washers and put it back together.

Bleed the front and rear lines but the brake pedal still goes to the floor and won't hold well. Figured the Master Cylinder was bad so I picked up a new one last night for my Duffs power brake unit. Bleed the lines again but still same problem, try to gravity bleed everything, still same problem.

Brakes worked before, WTH? The system acts like there is a leak, or air in the system, even if you pump the brakes it still ends up going to the floor.

Only real difference is the new brake lines. No leaks at all. Fluid flows easy and drains Master cylinder with no issues.

Id like to try replacing both of the soft lines but I need to pick them up local because of the time left before the event, anyone know what I should tell the local auto parts guy I need?

Anything else I should try?

 

[broncnaz]

Could be another bad MC it happens. I really dont see it being the lines again.

 

[bronconut73]

.I have seen aggressive bench bleeding hurt an mc.
Naz might be able to better explicate but you can damage the seal between the front and rear reservoirs/circuits leaving you unable to build pressure on either side.
That might not be the proper explanation but it's something like that.
I know you can damage an mc with "aggressive" bench bleeding cause I've done it

 

[chuzie]

Could be bad master. I have been through this too many times to assume a new master is a good master. I would suggest putting vice grips on the soft lines but I don't want you to ruin your braided. You can either swap the master OR pickup a couple inverted flare plugs for your MC ports. Plug the two ports and see if you have the same pedal issue. If you do, the MC is bad. If you don't, the MC is good and it is something else.

Pop the MC cap and SLOWLY press and release the pedal a couple times. Do you get a significant amount of return flow back to the reservoir? If so, I say you have air. Sometimes you get a little return, but a small fountain tells me air.

 

[chris]

Chuzie, I get a fountain when pressing the pedal from the front reservoir, nothing really when I let go.

I have the small plastic threaded plugs, should I try putting a set of those on to see if it gets stiff?

 

[chuzie]

Re: Brake problem, need to fix ASAP for the roundup!

Fountain on application is normal. On release is usually air.

U can try but I doubt they will hold. Worth a try I guess

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[chris]

Fountain on application is normal. On release is usually air.

U can try but I doubt they will hold. Worth a try I guess

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I tried the plastic plugs in the old MC and it was nice and stiff. So I tried looking where air might be trapped and figured maybe the two flexable lines going to the calipers since they were hump shaped. Disconnected them, drained and reconnected. Same problem.

Going to PU some plugs tomorrow and will start capping stuff off to see where the problem really is.

I really want to take this truck to the Roundup this year.

 

[broncnaz]

Fountain when applying the brakes could be a bad MC its bypassing internally. Of course they do push a little fluid normally maybe its just because the pedal goes to the floor. But I'd still suspect the MC.

 

[chuzie]

Re: Brake problem, need to fix ASAP for the roundup!

Agreed. By fountain I really mean squirt. ;-)

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[xcntrk]

You can bench bleed the MC right on the rig. Just cap off the output lines and pump the pedal a few times. Then hook back up, gravity bleed to all 4 corners, then pressure or vacuum bleed. Should do the trick..

 

[JohnJohn]

Chris,
I have a good working, original 77 Disk/Drum MC on the floor of my garage. Let me know if you want me to bring it to the Round Up. Your welcome to come down and get it but I think we are about 3 hours from each other.
Good luck tracking down the problem.

 

[ransil]

don't start replacing everything, the problem is the first thing you monkeyed with.

make sure the brake fittings are seated, back them off a few turns and re-tighten.

PS
never work on anything last minute before an event, never goes well...

 

[01Dudley]

Still sounds like air. Try bleeding with a vacuum pump.

 

[chris]

don't start replacing everything, the problem is the first thing you monkeyed with.

make sure the brake fittings are seated, back them off a few turns and re-tighten.

PS
never work on anything last minute before an event, never goes well...

Randy, I agree. I stopped at the Ol Parts store this morning, the real one without the computer on the counter and handed him my old brake line, called me two hours later and said he had one just like it on the shelf and another should be there by 1pm. Love those guys!

I'll swap the flexable lines and bleed the hell out of it again tonight.

01Dudley, if I had a vacuum pump I would use it. %) ;D

John,John, thank you for the offer, if this does not work I may try going back to the old manual camper special I had on there for 10 years.

 

[Rustytruck]

You can try reverse bleeding. take off the caliper leave the line connected. place a block of wood between the pads and tape or tie in place so you dont risk popping a piston. remove bleeded screw and wrap a little tefflon tape around the threads to help seal the threads. screw in the bleeder screw but dont seat it. hook up a hose and submerge into brake fluid. tie the whole thing up in a mannor the keeps the fluid flowing up as best as you can. now go to the master cylinder and disconnect the line. hook up a vacuum pump and suck the fluid up the line until you suck up good clean air free fluid. Start at the passenger front. and once you get good fluid set the bleeder screw and go to the drivers front.

Things to check. remove the bleeder screw and make sure its port holes are clear. poke a piece of wire into the calipers bleeder screw hole and make sure its clear too so fluid flows properly.

 

[chris]

You can try reverse bleeding. take off the caliper leave the line connected. place a block of wood between the pads and tape or tie in place so you dont risk popping a piston. remove bleeded screw and wrap a little tefflon tape around the threads to help seal the threads. screw in the bleeder screw but dont seat it. hook up a hose and submerge into brake fluid. tie the whole thing up in a mannor the keeps the fluid flowing up as best as you can. now go to the master cylinder and disconnect the line. hook up a vacuum pump and suck the fluid up the line until you suck up good clean air free fluid. Start at the passenger front. and once you get good fluid set the bleeder screw and go to the drivers front.

Things to check. remove the bleeder screw and make sure its port holes are clear. poke a piece of wire into the calipers bleeder screw hole and make sure its clear too so fluid flows properly.

Don't have a vacuum pump.

Bleeder screws are clear, made sure of that as they normally get plugged up with dirt.

 

[chuzie]

Re: Brake problem, need to fix ASAP for the roundup!

If ur gonna bench on vehicle jack the front up to level mc.

U can reverse bleed too. Get a 2 port bleed bottle. Fill with fluid. Hook low 10 psi air to one side and hook other end with tube to brake bleeder. Gotta have output line with small tube at bottom of bottle so u dont send air to system. Disconnect line from mc and let it piss. 4oz should do it.

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[01Dudley]

When go back to the parts store to get your hose get a hand vacuum pump. They are fairly cheap.

Don't have a vacuum pump.

Bleeder screws are clear, made sure of that as they normally get plugged up with dirt.

 

[chris]

Re: Brake problem, need to fix ASAP for the roundup!

So, replaced lines to calipers, replaced front pads, found slight leak from rear drum wheel cylinder, replaced both of them, bleed everything multiple times.

I lock up the rear wheels braking but the pedal still feels soft and goes to the floor. I'm here at the roundup, guess I'll ask Suzy from Duffs when I see her later this week.

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[Rustytruck]

Your conversion to disc on this 71 axle did you do the Ford Knuckle swap or the Chevy spindle/ disc swap. If its a Chevy caliper swap you might have to go up to a 1-1/16" Bore mastercylinder. Alot of Chevy swaps will not work with the smaller 1" Bore Mastercylinders. Do you get good hard brakes if you double pump and hold thats a sign of needing a larger bore. if you double pumop and hold and the peddle still sinks then the mastercylinder is bypassing or you have a leak somewhere.