I just rebuilt the brakes (4wheel manual drums) with new cylinders, shoes, hardware, hoses and hard lines (I'm saving up for disks, but not on budget for this summer). So, I've bleed the system four times around, doing it correctly, until no more bubbles come out. For the first two or three openings of the bleeder screw at each wheel, tons of bubbles come out. After that, no more, so I move on to the next wheel. It seems to be firming up. I didn't bottom out the master cylinder. I haven't seen fluid leaking from any fittings.Considering how much has been changed (new lines), about how many go arounds do you think it should take? Will it take 8 goes around? At what point do I consider that one of my fittings may be loose and air re-entering? Thanks.

 

You should stay at each wheel until you see the new fluid and a complete lack of bubbles. Does the brake pedal stay solid, or does it drift down when you have pressure on the pedal?

 

Any Sponginess at all indicates air or a leak

 

I've bled my brakes like crazy. The drums it had on it and now these new discs that I've got and can't get the sponginess out at all. I'm beginning to this I may have got a bad M/C

 

Braking 202 -- "Bleeding the Brakes" [/align] Bleeding the brakes requires a properly sized box wrench for the bleeder and the clear plastic bleed hose provided with your system. Good quality, non-silicone fluid is also a must. Baer Brakes has tested a wide variety of fluids and strongly recommends Performance Friction’s Z-Rated fluid #90016 for street and occasional track use (with Motorcraft PM1 our backup suggestion for this same duty). These two have been proven to be more effective than fluids that are often many times more expensive. For racing, Baer recommends and uses only Castrol SRF. Baer stocks and sells both the Performance Friction Z-Rated and Castrol SRF. Always remember, good to excellent brakes or fluid do not function without adequate cooling. In fact, the more serious your brake system, the more attention that needs to be directed to proper ducting, as they will generate more heat due to increased capacity. BLEEDING BRAKES IS NOT DONE WITH PRESSURE, IT IS PURELY A FUNCTION OF MOVING FLUID THROUGH THE SYSTEM. THE OBJECT IS TO DISPLACE AIR, NOT TO SEE HOW FAR FLUID CAN BE SHOT OUT OF THE CALIPER!
Proper Bleeding Technique Enlist someone who will help you bleed the brakes. Make sure they also read these instructions carefully (so they understand the goal). [ol][*]For systems which are essentially dry front and rear, start by filling the master cylinder with proper fluid. Pour slowly so as not to aerate the fluid.[*]Next, move to the first caliper, attach the clear plastic bleed hose to the bleeder and open it. Hold the hose upright so that you can monitor the escape of air bubbles. VERY SLOWLY stroke the brake pedal by hand or foot until fluid comes out. Now close the bleeder.[*]ACTUAL BLEEDING SEQUENCE: [ul][*]Have your partner very slowly, with modest pressure (approximately 25-30 lbs.ft.), stroke the pedal ONE TIME until hydraulic resistance is encountered. Ask your partner to hold at this point with the same modest and even pressure and notify you that he is “holding.�[*]Open the bleeder, letting the pedal go to the floor or until it stops, using the same modest level of pressure, then close the bleeder again. Notify your partner “the system is sealed.� He can then slowly release pedal pressure.[/ul][*]Repeat the BLEEDING SEQUENCE (never stroke the pedal more than one time) until all signs of air are purged (no bubbles) from fluid. IMPORTANT [ul][*]NOTE: DO NOT LET THE MASTER CYLINDER RUN DRY! Be sure to check the fluid level after every third bleeding sequence or sooner if reservoir volume is very small.[/ul][*]Before moving to the next caliper, take a small block of wood or a plastic hammer and carefully tap the caliper to dislodge any additional air bubbles that may be trapped. Then bleed one last time.[*]Move to the next caliper and repeat the procedures previously outlined. Continue until all calipers have been bled. Before re-installing wheels and placing the car on the ground, we recommend you carefully wipe clean all caliper surfaces, hose joints and fittings, making sure they are all dry and free from seepage. If not, inspect and tighten appropriately. Spray all rotor surfaces with Brake Kleen® or a similar product to remove all dirt and oils from your hands that may have been transferred to the rotor during assembly. Also remember to remove the nut that has been holding rotor in place before attempting to re-install the wheel.[/ol] For street use, as with any time you open the brake system, it may be advisable to repeat the bleeding procedure after driving the vehicle for a day, as driving the car may dislodge some additional air bubbles. For competition cars, we recommend repeating this procedure directly after at least the first two sessions the car is on track and at the beginning of each race weekend thereafter. Even if your pedal is high and firm and additional bleeding is deemed unnecessary, always inspect the calipers, hoses and fittings after the first outing for signs of any fluid seepage and correct immediately.

 

Did you change the M/C, or are you sure it's never been run dry? Otherwise you'll need to bleed the master cylinder too.

 

Thanks for chimeing in. Well.. I'm familiar with proper bleeding. The pedal seems to firm up a bit after each time around, but it still slowly sinks down in the test drive down the block. The car will stop, as the pedal firms up when it gets closer to the floor. I'm thinking there must still be a lot of air in there because of all the new lines. Thats why I'm wondering how long the process should take. If I did brakes more often than once every ten years, I'd probably have more experience in this. So, keep bleeding and bleeding? I will try bleed the master in the car if it doesn't get too messy. If air is leaking back into the system, shouldn't I also see fluid leaking out when pressurized, right? All looks dry as I can tell.

 

Seems like everyone has a different method for bleeding brakes.

I start out with a large size bottle of brake fluid, with the intent on using it all. (Otherwise it sits on the shelf and soaks up water..right?)
I also use a 2' length of clear tubing and a clear plastic liter bottle. The tube goes through a drilled hole in the top of the bottle cap and down to the bottom (where I have a bolt tied to it). The bottle starts out with about 2" of fluid.

Starting at the back right, I hook it to the bleeder valve and have the helper start pushing. I watch till the clear tubing is completly free of bubbles, then close the bleeder valve on the pedal down stroke.

Refil the M/C and repeat for the other 3 corners.

Then repeat the entire process again... till you've gone through the $3 bottle of brake fluid.

This method keeps any air from being sucked back into the bleeder.

 

If the pedal firms up and then gets soft, than air is present. "Pascals" law is always a good thing to remember when it comes to brakes. "Pressure applied to a confined fluid is transmitted undiminished in all directions, and acts with equal force on equal areas, and at right angles to them". Thats the basic of any hydraulic system. Given this, brake fluil is non-compressable, so, when you hit the brake, it should be solid (their is some expansion in the rubber hoses that allows the pedal to give a little). However, if any air (air is very compressable) in the line or system, that will give a spongy pedal. When you pump it up, and it gets firm, the air is compressing. But when you let your foot off the brake, the air expands again and the pedal gets soft. A bench bleed is necessary to relieve the master cylinder piston of any air. Often this is overlooked. I ususally use a vacuum pump to clear the lines of most of the air, then use the method that James described. If you have a loose fitting, you will see fluid leaking also. I feel your pain as Iwill chasing a brake issue today very simular to yours. I would not rule out a bad master cylinder either. It can be bypassing. You may want to look at the (inside the car) firewall to see if any fluid is leaking. Sometimes it will run down the firewall and under the carpet withoug being noticed. Good luck and post the solution when you get this fixed so we all can learn.

 

OK, I'm about to get started again. The new lines, hoses and cylinders were full of air and empty of fluid when installed, so that entire volume of air will have to come out, right? I think I need to patiently keep bleeding. I did buy a rebuilt master from Auto Zone last night, in case.
Thanks for the suggestions. I'll keep you posted.