Brake Bleed help

[BB767]

Trying to bleed the brakes and having a problem I hope someone can figure out. We are doing it manually the old fashioned way with one person pushing the pedal and the other opening and closing the bleed valve. I have done this before on other vehicles and in fact it worked fine on the front brake system. (I have installed another reservoir to make the two systems fully independent, front and rear.) We have been pumping on the rear system for over three hours and have pushed over a half a gallon of fluid through it. We are still getting bubbles out of both sides of the rear brakes. Here's a clue that I do not think is normal. When the pedal is depressed, nothing happens in the reservoir (which I think is correct) but when the pedal is released, air bubbles come out of the hose into the reservoir! I just noticed this when trying to figure out where all the air in the line was coming from and I do not remember every seeing this before. It appears to me that the cylinder is somehow sucking in air and releasing it into the lines and back into the reservoir, however there are no fluid leaks whatsoever anywhere in the system. So, what is wrong?

[GoDadGo]

BB-767

I've had good results by simply doing an Extended Gravity Bleed before doing the regular (Pump It / Pedal Pushing) brake bleed.

1. When I did the bleed, I raised the front of the car a pretty good bit and did a Gravity Bleed starting with the longest run first and did each wheel individually.
2. Raising the front of the car will likely ensure that you've got the reservoirs above the plane of the master cylinders and it helps to move fluid to the rear of the car.
3. Once I completed both the front and rear, I then did a regular (Pump It) bleed with a bit of a twist by bleeding the passenger side 1st, then the drives side.
4. This process allowed the balance bar on the pedal box to even out and totally bottom out, thus causing the air to be forced out.
5. I repeated the process a few times and checked to make sure that the balance bar went evenly and all the way down.
6. Please be advised that if you bleed the front and back separately when doing the (Pump It) bleed method you probably won't bottom out the master cylinders.
7. Basically, that balance bar pedal assembly needs a little finessing in order to adequately bleed the system.

My gut feeling is that the balance bar set up is giving you as much fun as it gave me until I understood exactly what was happening.

Good Luck & I Hope This Helps!

Steve

[michael everson]

I just went through the same thing last week. I ended up pressure bleeding them using a bike tire pump and a modified cap for the reservoir. I can send you the cap as long at you return it.
Mike

[CraigS]

I just went through the same thing last week. I ended up pressure bleeding them using a bike tire pump and a modified cap for the reservoir. I can send you the cap as long at you return it.
Mike

I agree. Find a way to pressure bleed. You don't need much pressure, in fact the CNC folks who made my MC setup recommend staying at 5# max. A fish tank pump works great. Heck, blow up a balloon.

[Mark Dougherty]

pressure bleeding works well.
I have had good luck with a couple other things though.
1) fill the res. to the top then crack the banjo fitting loose where it goes into the master cyl.
this will make sure you do not have an air bubble over the master cyl.
2) extend the master cyl. push rods as far out as they can go bringing the pedal way up.
what this does is lets the master cyl. move full travel getting the last of the air out.
3) do a 3 person bleed, meaning open 1 front and 1 rear caliper at the same time.
again this will allow the pedal to go full travel

[michael everson]

Not sure whats going on but I have never had such a hard time bleeding the rear brakes. someone else on here said that maybe the fittings and hoses are too small and when you release the pedal too fast it sucks air in through the rear seal rather then fluid through the hoses.

I spent 2 days working on it to no avail. The only way was pressure bleeding. My setup is the black masters, red small diameter hose into a Y and out to a single reservoir. Rear calipers are the standard T-bird calipers supplied with the new IRS setup.
Mike

[Gromit]

Going out on a limb here you did "bench" bleed the master cylinders I would want to see that working before I started going to the wheels

I would think putting a finger over the end of the open line to make a check valve would help rule out the master cylinder

And yes it would be a pain but as a test swap the front and rear lines at the master to isolate the problem

Good luck and speedy resolution
Chris AKA Gromit

[michael everson]

In my case I bled the master. Even replaced it with another. Same exact problem. 4 hours of bubbles before I gave up and pressure bled them.
Mike

[CraigS]

I have also come across the threads on the bleeder leaking. So my procedure closes the bleeder while there is still fluid coming out. As the pedal is pushed the fluid comes out at a fairly steady flow. As soon as that flow slows slightly, I close the bleeder. This way air can not get sucked into the system as the MC returns to rest.

[slpro1207]

I went through the same problem as BB767. Spent hours trying to get the bubbles out. Finally after a suggestion on the forum I removed the master cylinders and bench bled them. Reinstalled and bled the system normally and problem solved.

[Itchief]

For me the pass rear was the pain

I used a vacuum pump bleed from HF and put some teflon tape on the top threads of the bleed nipple so that it would not draw air when using the pump and just barely crack the bleed nipple

Without the teflon tape it will never stop bubbling

Rick

[Papa]

I have the CNC reservoir and their bleeder cap. Fist bench bleed the master cylinders by connecting some tubing from the master cylinders and into the reservoir(s). Fill the reservoir with fluid and pump the pedal until you don't have any bubbles. Be sure to keep the reservoir full! Now reconnect your lines and start with the corner furthest from the reservoir. With pressure applied via a pump on the CNC reservoir (your application may be different) and a collection bottle attached to the caliper bleeder, slowly crack open the bleeder. Close it and top off the reservoir, then repeat until you have no bubbles. Move to the next closest wheel and repeat.

[BB767]

Thanks all. I think Mike has a good guess as I think I can hear air being drawn into the M/C as the pedal goes out. I will try each of the above suggestions until one works!

[michael everson]

BB767. I could too. Just couldn't figure out where. Must be the rear seal in the master.
Mike

[Cyclotic]

I have also come across the threads on the bleeder leaking. So my procedure closes the bleeder while there is still fluid coming out. As the pedal is pushed the fluid comes out at a fairly steady flow. As soon as that flow slows slightly, I close the bleeder. This way air can not get sucked into the system as the MC returns to rest.

I bled my brakes this way, too. Worked fine for me.

[NAZ]

Can't help you with a procedure as I've never had a problem bleeding the dual M/C with balance bar. I must be livin' right as so many others have had issues.

However, I can give you a suggestion to help a one-man operation try to use some of these multi-person procedures. Invest in "solo" bleeder valves -- they can be purchased in a variety of sizes and threads to fit most applications. Retailers like Summit Racing carry them. These replace the standard bleeder valve on the calipers with ones that have a check valve. When loosened to allow fluid out, the spring loaded check ball will open to allow fluid to flow out of the caliper (both air & liquid) but close to prevent air from being drawn back into the system. Simply attach a hose from the "solo" bleeders and place into a collection bottle. You can bleed one are all at the same time by yourself. You don't have to man the valve while you pump the brakes but you still have to keep an eye on the reservoir.

This is much like the old school method of placing a hose submerged in a bottle of brake fluid to prevent air from being drawn back into the system. But unlike the old school method, nothing can be drawn back into the system including contamination as would sometimes happen if not careful with the submerged method.

[michael everson]

The problem BB767 and I were having has nothing to do with the bleeders. Sounds like both of us were getting air at the master. I could actually hear it as I released the pedal. Not sure whats going on but I have never had this happen in 70 plus builds. This is the first car that I have built utilizing the smaller black masters. The front bled right away. There was no way the rears wereg oing to bleed the conventional way.
Mike

[GoDadGo]

The problem BB767 and I were having has nothing to do with the bleeders. Sounds like both of us were getting air at the master. I could actually hear it as I released the pedal. Not sure whats going on but I have never had this happen in 70 plus builds. This is the first car that I have built utilizing the smaller black masters. The front bled right away. There was no way the rears wereg oing to bleed the conventional way.
Mike

Mike,

Did your "Pressure Bleed / Bike Pump Rig" do the trick?
Did Wilwood change the design of the Masters when they went to the coated versions?

Steve

[BB767]

Pressure bleed using a basketball pump did the trick in half an hour. Works great.

[CraigS]

That basketball pump is a great idea!

[phileas_fogg]

That basketball pump is a great idea!

That's not all. When you start making soft lines with AN fittings, you can buy a test adapter set and make sure the lines don't leak before putting them on the car. The sets come in multiple AN sizes, but I "standardized" everything on my car to -6AN so I only needed a single test fitting. Then using the bicycle pump and a bucket of water, I call dial the pressure up to 2x what the line will experience, flex the hose all around the fitting, and get comfortable the line won't leak. This technique works for everything except the power steering pump feed line (which is a couple of orders of magnitude more than any bicycle pump can generate).

Cheers,


John