Brake Bleeding Nightmare

[SFEbody]

Hello my friends, So have my Resto near complete, but having issues getting the brakes to bleed.

So its an all new stainless line 70 barracuda with stock disk/drum setup. I started by bench bleeding the master cylinder and it went well, then started at the passenger rear and could not get a good flow, only very bubbly slight fluid coming out. ( using a pneumatic bleeder setup) Tried the drivers rear, then pass front and then drivers front, all with the same bubbly results. I did have a couple fitting leaks which I have tightened.... any advice to get good flow would be very appreciated. BTW, the pedal is very soft and goes to the floor when running

Brian

 

[gzig5]

So you are using something like a Motiv bleeder that pressurizes the master? You should be able to do the passenger rear until solid fluid comes out, might take longer than you think. Make sure you have enough fluid in the master to replace what fills the pipes. Another way I have used in the past is to gravity bleed. Open the bleeder and just let gravity take over. I guarantee fluid will find it's way to the leak within an hour. Can't think of anything being wrong in the master that would prevent getting decent flow at all corners.
The pedal goes to the floor because you have a lot of air in the system.

 

[Steve340]

Have you checked the clearance between the master cylinder and the brake booster pushrod?

 

[Chryco Psycho]

Stainless can be very difficult to get to seal , probably still have air getting in somewhere .

 

[SFEbody]

Stainless can be very difficult to get to seal , probably still have air getting in somewhere .

Whats the trick Chryco with Stainless lines, I have tightened tot he point i am afraid to snap the fitting

 

[moparlee]

You may have to check all the flares for any burrs or imperfections. I used a piece of emery cloth on the end of small tapered dowel to smooth out an imperfection that prevented a good seal.

 

[terrywalker]

I have tried the bleeder kits and I still like to bleed them the old fashioned way with a clear jar and about 1/2" of brake fluid in it. I put a 1 foot long snug fitting piece of hose over the end of the bleeder valve on the wheel cylinder or caliper. I have my wife get in the vehicle and as she presses the brake pedal, I open the wheel cylinder or caliper bleeder until the pedal is on the floor and she holds it there until I shut the bleeder and then she lets off brake pedal. With the other end of the hose in the brake fluid in the jar, I can see the air bubbles go out of the line. We keep doing it until brake fluid comes out the bleeder in a solid stream. We start at the right rear, then the left rear, etc. Yeah, it takes two people but it sure works and I just pour all of the clean brake fluid from jar back into master cylinder and add as needed.
Terry W.

 

[MoparCarGuy]

Pressure or vacuum bleeding can be difficult if the combination valve does not allow flow to the wheel cylinders and calipers.
Go with terrywalker’s proven method and then, if still not working, check those stainless connections for leaks and air infiltration.

 

[SFEbody]

Thanks guys, will have my beautiful wife be a pedal pusher.....

 

[moparlifer]

I heard somewhere that sometimes the calipers may have a high spot the air goes to that is above the caliper bleeder.
I have heard that you could remove the caliper and rotate it up so the the bleeder screw is at the very top.
This may help purge any trapped air that doesn't push out when bleeding.
I have not done this but it makes sense to me.

 

[Buckminster]

I heard somewhere that sometimes the calipers may have a high spot the air goes to that is above the caliper bleeder.
I have heard that you could remove the caliper and rotate it up so the the bleeder screw is at the very top.
This may help purge any trapped air that doesn't push out when bleeding.
I have not done this but it makes sense to me.

In addition to moparlifer's comment. I've experienced issues bleeding brakes if there is anything preventing the pedal from coming all the way up. The piston must be able to retract fully to open the port in the bottom of the master cylinder to allow fluid to get in "front" of the seal. Once the seal passes the port in the bottom of the master only then will it build pressure. conversely, if it is not allowed to replace the air with fluid due to the piston being limited from retracting all the way, you will get a soft pedal. With tolerances on parts these days, I've seen more of these types of issues.

 

[MoparCarGuy]

It is easy to chase a problem and overlook the simplest possible solution. I am hoping your bleeding procedure goes well the old-fashioned way and your stainless tubing connections are not letting air into the system on pedal release.
That being said, a problem that was mentioned and may need to be checked is the brake booster rod to master cylinder piston clearance. I thought mine was okay but when checked it was almost 1/4" gap between the booster rod and the piston. I ended up buying one of the better tools HERE. Adjusting the brake booster rod to about .020" made a serious pedal feel difference.
Not saying yours is excessive but something else to consider if you continue to have issues.

 

[Steve340]

If anything he will not have enough clearance therefore not uncovering the compensating port in the master cylinder.

 

[MoparCarGuy]

If anything he will not have enough clearance therefore not uncovering the compensating port in the master cylinder.

Exactly why it must be checked. Too much or too little is bad.

 

[Gary Kitchens]

Don’t forget that new master cylinders can be bad right out of the box.

 

[terrywalker]

In addition to my reply #7, I've had recently doing a system bleed where no air bubbles were visible in the brake fluid in the jar and the pedal was soft. It turns out the bleeder screw was plugged up with a hard grit that had gotten into the rear wheel cylinder.. I removed the bleeder screw and fixed the problem and flushed the wheel cylinder out. There are many good suggestions here to try until you find the problem.
Terry W.

 

[Gary Kitchens]

If the pedal is still soft after you get no bubbles out of your brake lines, then you have misadjusted rear shoes and you need to adjust those shoes further out until they just start dragging on the rear drums after they’re adjusted and re-centered. Just a tad. The self adjusters will normally cover the rest as time goes by.

 

[MoparCarGuy]

If the pedal is still soft after you get no bubbles out of your brake lines, then you have misadjusted rear shoes and you need to adjust those shoes further out until they just start dragging on the rear drums after they’re adjusted and re-centered. Just a tad. The self adjusters will normally cover the rest as time goes by.

This is very good info. A visual inspection of the rear brakes can identify the problem Gary mentions above.
True story:
I had a mushy pedal after I finished my Cuda's restoration. I theorized it was due to a lot of different things. Big cam/low vacuum, air in brake system, bad master cylinder, etc.
After actually troubleshooting and checking the rear brake shoes, I found that the driver side rear wheel cylinder pin had come out of the shoe and was not expanding the brake shoes. The pin was extending over to the curved metal portion of the shoe and the spring was holding it in place under spring tension. This simulated a mushy pedal as the wheel cylinder piston was expanding with no resistance. After adjusting the shoes outward and putting the cylinder pin back in place, the pedal was solid.

In troubleshooting, I was always told "visual first". Certainly held true for the problem above so I agree with Gary on checking your rear brake shoe adjustment as well.

BELOW: A picture of my actual rear drum brakes after I put the pin back in place.
Marked up to show where the cylinder pin was hitting the RED line area and slipping down under the spring tension.

 

[SFEbody]

Wanted to update, I finally bought a universal kit that goes on the MC anbd pumps up at 15PSI, it has a tank that continuesly feeds the MC as you open the bleeder valves. I am happy to say, I now have normal brake pedal and they are operating as designed. Thanks to all the experts whom directed me to solve my issues.

 

[AUSTA]

Hello my friends, So have my Resto near complete, but having issues getting the brakes to bleed.

So its an all new stainless line 70 barracuda with stock disk/drum setup. I started by bench bleeding the master cylinder and it went well, then started at the passenger rear and could not get a good flow, only very bubbly slight fluid coming out. ( using a pneumatic bleeder setup) Tried the drivers rear, then pass front and then drivers front, all with the same bubbly results. I did have a couple fitting leaks which I have tightened.... any advice to get good flow would be very appreciated. BTW, the pedal is very soft and goes to the floor when running

Brian

When using a vacumm bleeder i put white sealant around the thread on the bleeder screw as the the bleeder tends to suck air in from around the thread (the path of least resistance ) rather than sucking fluid once all the bubbles have gone follow up with a pump ,hold & release method if pedal is still soft check rear brake pad adjustment