• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Master Cylinder need help

B RON CO

Contributor
Bronco Guru
Joined
Jun 29, 2016
Messages
2,412
Loc.
Statesville, NC
Hi, I'm guessing the hole in the brake line is too big for you. The banjo bolt must fit tight in the hose end.
Measure the banjo bolt and the iD of the fitting.
Good luck
 

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,033
I got the new hoses from WH I can't stop them from leaking . I have changed the copper washers and they both still leak when you mash the brakes.

You need the size to match the banjo bolt, so confirm that first. If that's good, then next you should inspect the sealing surfaces for any significant flaws, nicks or dings that would keep them from sealing...which I would believe possible if it were only one side leaking. If it's both, then I would anneal the copper crush washers by heating them up with a torch and then quenching them in water. When annealing copper, it will turn black and then a cherry red, at which point you should quench. With an Oxy-Acetylene torch, it take less than 20 seconds at 3-4 inches away in my experience.

I've gotten batches of copper crush washers that have not been fully annealed, and tended to seep fluid no matter what. Rather than over-torquing the fasteners and risking damage to either the banjo bolts and/or calipers, I'd make sure the issue isn't the crush washer first.

Tobin
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
Not to high jack the thread but I have related question to this as well. I was unaware of needing to bleed the MC prior to install. Can you get away with this? I'm assuming yes but you'll just need to bleed the brakes over and over till all the air is gone. Correct me if I'm wrong ?:? ps I did all 4 disc swap, new booster, new mc, and all stainless lines w/ parking brake delete 83 monte carlo calipers on the rear.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
Many people get away with it actually.
But the proper and long-time accepted (and expected) method of installing a new master is to bench bleed it first.

Been that way as long as I can remember, back before we even were using dual-reservoir master cylinders.
And even though "bench-bleeding" is called that because it can be done on the work bench prior to installation to make sure it's good (saves time, frustration and shop labor costs) it's just as easy (easier?) to do on the vehicle, as has likely already been discussed here (will have to go back and read it again). But while one person can do it on the bench, it usually takes two people when already on the vehicle.
(edit: it doesn't really take two to bleed a master on the vehicle either, unless it has a bleeder screw. Using the typical fittings in the output ports, one person can do it easily)

If yours is already installed, and already plumbed and bled, give it a try. If it feels good and solid you may have just gotten lucky.

Paul
 
Last edited:

Pa PITT

Contributor
Bronco Guru
Joined
Jul 15, 2005
Messages
11,252
Loc.
Stephenville TEXAS
.. RY . I've got to where I don't bleed mine the standard way.
I'm Always by my self.
... SO I get it all installed . I go to the rear back passenger side . Fill the M/C & OPEN THE BLEEDER ON THE REAR . & GO BACK TO THE FRON & POUR IN BRAKE FLUID UNTIL I'M SURE IT RUNNING OUT THE BACK END . I actually run back & fourth watching for bubble at the rear. . THEN i DO THE OTHE 3 THE SAME WAY .
... I think this removes the air easier than the original way.
& You can add a rubber hose from the blender to a bottle & not have the mess to clean up later.
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
.. RY . I've got to where I don't bleed mine the standard way.
I'm Always by my self.
... SO I get it all installed . I go to the rear back passenger side . Fill the M/C & OPEN THE BLEEDER ON THE REAR . & GO BACK TO THE FRON & POUR IN BRAKE FLUID UNTIL I'M SURE IT RUNNING OUT THE BACK END . I actually run back & fourth watching for bubble at the rear. . THEN i DO THE OTHE 3 THE SAME WAY .
... I think this removes the air easier than the original way.
& You can add a rubber hose from the blender to a bottle & not have the mess to clean up later.


thanks Pa!
 
OP
OP
DEEPWOODS

DEEPWOODS

Contributor
Bronco Guru
Joined
Jul 29, 2007
Messages
1,100
Sat. I pulled the line to the passenger rear caddy caliper and Plugged it. I then had a good firm pedal so I at least now know it’s my problem . I found instructions from Chuck at BC Broncos on how to adjust it I thought I had it fixed and checked it this morning and it’s back to doing the same thing first pump to the floor I think that maybe the caliper piston is drifting back is that even possible?
 
OP
OP
DEEPWOODS

DEEPWOODS

Contributor
Bronco Guru
Joined
Jul 29, 2007
Messages
1,100
A big Thanks to everyone helping me with this brake mess. So you are correct the new front lines are for 7/16 banjos and the rebuilt calipers I got are the 10mm metric banjos bolts. I have ordered more new lines with the smaller hole I hope this will fix this problem also ordered a right rear caddy caliper. I adjusted the rear as per the BC instructions and can’t find anything wrong with them maybe the stud the lever is on is letting air get behind the caliper piston or the cam action is not working correctly.Thanks again for all your help Keith
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
My truck is doing the same thing....i can't find a leak anywhere ...
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
Make sure the piston in the master cylinder goes all the way back when you let off the peddle Look in the master cylinder at the port in the bottom of the rear master cylinder well. make sure the piston clears the well. If it doesn't you need to adjust the rod between the master cylinder and the booster.
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
Make sure the piston in the master cylinder goes all the way back when you let off the peddle Look in the master cylinder at the port in the bottom of the rear master cylinder well. make sure the piston clears the well. If it doesn't you need to adjust the rod between the master cylinder and the booster.

Thanks I'll give that a look, I also noticed when the engine gets a little gas the pedal gets firmer. I may have a vacuum leak as well, but over all is still soft
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
Make sure the piston in the master cylinder goes all the way back when you let off the peddle Look in the master cylinder at the port in the bottom of the rear master cylinder well. make sure the piston clears the well. If it doesn't you need to adjust the rod between the master cylinder and the booster.

Thanks Rusty...I haven't got to it yet but Ive had this picture on my phone. Youre saying I'll need to adjust rod "B" in the photo? Just for clarification... ;D

IMG_9292.jpg
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
These are other things I'm going to try....

Gravity Bleeding
Calipers, especially rear calipers with all the parts and crevices can trap air inside them. Gravity bleeding is the best method we have found to bleed calipers. To gravity bleed, take the caliper off the bracket but leave the flex hose connected. Take the top off the master cylinder and keep filled. Hold the caliper so the flex hose is going slightly uphill to the caliper. Open the bleed screw so fluid and air will slowly come out of the bleeder. You can move the caliper around, hit it with a rubber hammer to knock air bubbles loose. When the fluid runs clear, do the other side and then do both calipers again. (Do not push the pedal until you install the calipers on the rotors) Remember that air bubbles rise. The bleed screw must be at the top where it breaks into the caliper cylinder to get the air out. (The bleeder might be pointing to the front) Rear calipers have their mounting screws one above the other. Front calipers sit on approximately a 45-degree angle.

Would this hold true? Technically they're front calipers for a monte carlo...


Problem: Pulling piston back too much.
Fix: Adjust caliper brake arms.

Problem: Defective caliper.
Fix: Replace caliper.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
Thanks Rusty...I haven't got to it yet but Ive had this picture on my phone. Youre saying I'll need to adjust rod "B" in the photo? Just for clarification... ;D

I believe he was referring to the one at the opposite side of the booster. The rod that comes in physical contact with the back of the piston in the master cylinder.
It's also the easiest to adjust!

You have to make sure of two things:
1. That is not touching the back of the master cylinder when your foot is not on the pedal.
2. And that the gap between the tip of the rod and the back of the piston is very tiny. VERY tiny.

Less gap means brake action sooner when you first start to push the pedal. Too little gap, as in touching, means the master cylinder never releases fully and can't do it's job.
It's the most common reason for long pedal travel in a boosted system when all else is working as it should.

Paul
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
"Bleeders Up!"
Would this hold true? Technically they're front calipers for a monte carlo...

Caliper, drum brake cylinder, clutch, whatever... If it's a closed hydraulic system where air is not supposed to be in the system at all, this is at least one universal truth. The bleeder MUST be at the highest point on the component, and aimed upward at least mostly (they're not always vertical, but still pointed roughly up) for there to be a chance to bleed all the air out using standard methods.
And even some non-standard methods are ineffective if the bleeder screws are not pointed up.

Doesn't matter what type of component, or where it was originally from (front caliper used on the rear for example) if the bleeder is pointed in a funky direction, you need to either fix it or bleed it with the previously described method where the caliper is actually removed during bleeding so that you can point it in the right direction.
No factory does that though, as far as I know. It's up to the designer of the kit, the installer of the parts, or the end-user/bleeder dudes (us) to make sure things are oriented correctly.

Paul
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
Thanks paul, im going to also replace my front and rear rubber hoses first, I have no clue how old they are...shoulda done it earlier. They might be bulging and i don't even know it..
 

rydog1130

Sponsor/Vendor
Bronco Guru
Joined
Jun 19, 2014
Messages
4,020
UPDATE: I changed out my flexible rubber hoses, bled the brakes again, and adjusted my push rod on my vacuum booster. Truck stops a lot better, I can push the petal down about 25% of the way and it will hold the truck to shift into gear, but overall the brakes still feel soft. Should I bleed them again since I lengthened the push rod or will that not make a difference? Only thing left I havnt tried is gravity bleeding the rear calipers...
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
did you adjust the rod to spec? Or is it still in the experimental adjustment phase? If you think you can move it farther out without touching the back of the piston, then by all means give that a try.

and no, you do not need to re-bleed just from this adjustment. Mechanical and hydraulic are usually separate and don't necessarily respond to cause-and-effect rules.
but that's not to say you should not bleed again. Spongy is still air, or something flexing.
So soft as in "spongy" needs fixing. Soft as in "long travel" can still be different things.

Paul
 
Top