Bevans077 Posted September 8, 2017 Share Posted September 8, 2017 Hello everyone! I was just out in the garage the other day trying to bleed the brakes on my 29' 75 and I couldn't get fluid to the rear wheel cylinders. After a little investigation I noticed the master cylinder does create pressure when the pedal is pushed, but when it is allowed to return to the realised position it sucks back in fluid from the line. So... Am I missing something? I need your expert advice Link to comment Share on other sites More sharing options...
keiser31 Posted September 8, 2017 Share Posted September 8, 2017 Did you adjust the brakes shoes before trying to bleed? If you do not do that first, you will have loads of trouble bleeding them. Link to comment Share on other sites More sharing options...
ArticiferTom Posted September 8, 2017 Share Posted September 8, 2017 You may have a collapsed rubber brake line going to the axle . Causes pressure in the liner to seal off . Would explain both going out in rear loosen fitting on axle see what you get there . Link to comment Share on other sites More sharing options...
Bevans077 Posted September 8, 2017 Author Share Posted September 8, 2017 No, I did not adjust the shoes, I will look into that. Would I have to fill the lines before trying to bleed them? Link to comment Share on other sites More sharing options...
keiser31 Posted September 8, 2017 Share Posted September 8, 2017 (edited) Adjust the shoes so that they barely touch the drums. If you hear a LITTLE or FAINT rubbing, it's good. Once you adjust the shoes, fill the master cylinder with fluid. Start bleeding at the farthest wheel cylinder from the master cylinder and work toward the front left. Add fluid to the master cylinder between bleeding of each wheel cylinder. If the car is a regular left-hand drive car, bleed the right rear wheel cylinder first. Next, do the left rear, onto the right front and finishing with the left front. You may have have to do this bleeding procedure about three times. Drive the car around once you get some brakes and re-adjust after a few miles. Edited September 8, 2017 by keiser31 (see edit history) Link to comment Share on other sites More sharing options...
Spinneyhill Posted September 8, 2017 Share Posted September 8, 2017 IF the rear brakes are not working because the flexible line is blocked, it is a fair chance the front flexible lines are nearly blocked too. All three flexible lines are usually pretty similar so buy a set and replace the lot, once you have ascertained there really is no fluid going to the back. Test: put a person in the driver's seat, with one rear wheel jacked up and supported securely. Apply brakes and see if you can turn the raised wheel. If you can, either brake line is blocked, or the shoes are miles away from the drum = way out of adjustment, probably on more than one wheel. Link to comment Share on other sites More sharing options...
Bevans077 Posted September 10, 2017 Author Share Posted September 10, 2017 I am getting air out of the bleeder on the rear wheel, but the more I try to bleed it the less I get. The brake drums have not been apart since it was last driving 2 years ago. So.. I am going to have to check them out, but is it normal for the master cylinder to be sucking back in just about as much as it puts out? Link to comment Share on other sites More sharing options...
ArticiferTom Posted September 10, 2017 Share Posted September 10, 2017 Yes , So brakes release . But it has to have all air forced out of system to remove the spongy-ness . There is a valve in end of master to limit speed or return, I believe . Other please chime in on that ! If that where bad brakes would feel like there pushing your foot back not the spring pulling pedal back . Link to comment Share on other sites More sharing options...
Spinneyhill Posted September 10, 2017 Share Posted September 10, 2017 The fluid has to return to the master cylinder for the brakes to retract. I don't know your technique, but.... after each pedal downstroke, release it slowly up to prevent problems in the master cylinder. The usual instruction is to not use full pedal travel so you don't pump around the dirt in the master cylinder. I had never read this instruction so always went to the floor. When I did read about it, on these fora, I took the master cylinder out to check. It was spotless. I can get three full strokes before having to add fluid to the master cylinder. Another trick is to use a clear bleeding hose so you can see the fluid and air and run it UP from the nipple before down into your collection jar. This way, there is a little fluid available to run back into the cylinder rather than air. It also allows me to bleed the brakes on my own: set it up, release the bleed nipple, three strokes, close the nipple, refill master cylinder, repeat. You can see the air in the tube. I keep going until clean fluid comes out. Link to comment Share on other sites More sharing options...
Bevans077 Posted September 20, 2017 Author Share Posted September 20, 2017 Thank you for all your input, it's just so hard to find time to get out in the garage and actually work on it. Link to comment Share on other sites More sharing options...
c49er Posted September 21, 2017 Share Posted September 21, 2017 Maybe the rear wheel cylinder rubber cup lips are blocking the fluid inlet holes so you cannot bleed the brakes. This can happen because the shoe lining is too thick and that causes the pistons and cups to be pushed in too far if the cups are at the end of the pistons. I have had this happen and also seen fluid leak past the piston towards the cylinder boot and leak on the shoes. Link to comment Share on other sites More sharing options...
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