rapidride2 Posted May 28, 2014 Share Posted May 28, 2014 1952 Buick Roadmaster: Apple hydraulics rebushed/rebuilt master cylinder and rebuilt all wheel cylinders. Ive ran new stainless brake lines and rubber hoses. New linings and spring kit. Lightly turned drums. Basically EVERYTHING on the brake system is new except the proportioning valve which was cleaned thoroughly and blown out with compressed air through each port.I have a soft pedal that goes to the floor with minimum force. I've adjusted the drum brakes thinking they were out of the wheel cyl's range. With the pedal to the floor i can literally still turn all of the drums by hand.I have bench bled the master cyl 2x. I then cracked the discharge line to free any more possible air. with pedal held down.I 'buddy bled each wheel cyl 3-5x. I have also used a mity-vac vacuum bleeder to bleed to 15-20hg vacuum at each wheel an additional 3-4x. ALL WHILE KEEPING THE MASTER CYL. FULL. I thought about hooking up a pressure gauge to check hydraulic pressure at the master cylinder but I am not sure how much pressure I should have? I can only think a bad new/rebuilt master cylinder at this point. I am getting fluid to each wheel cylinder. If my proportioning valve was blocked I would think i would have no brakes but a rock hard pedal? Instead I have no brakes and a soft pedal.Any suggestions? Link to comment Share on other sites More sharing options...
JohnD1956 Posted May 28, 2014 Share Posted May 28, 2014 All four drums scrape the brake shoes? Link to comment Share on other sites More sharing options...
rapidride2 Posted May 28, 2014 Author Share Posted May 28, 2014 Right now I adjusted all 4 drums to lightly drag the drums. When i pump and press the brake pedal I have the exact amount of light drag. Link to comment Share on other sites More sharing options...
Guest shadetree77 Posted May 28, 2014 Share Posted May 28, 2014 Get a flashlight and look down inside the MC. Make sure there are TWO holes in the bottom of the reservoir. A tiny one the size of a pin head and a bigger one. I had my MC sleeved and rebuilt and the chuckleheads forgot to drill the larger hole. I spent a LOOOOONG time and countless $ on brake fluid for bleeding before I noticed mine was missing the larger hole. Link to comment Share on other sites More sharing options...
rapidride2 Posted May 28, 2014 Author Share Posted May 28, 2014 Shade tree. I remember seeing the small one. Regarding the larger hole, will i see this pass by the bottom casting hole if i slowly depress the master cylinder plunger? I will check. Link to comment Share on other sites More sharing options...
rapidride2 Posted May 28, 2014 Author Share Posted May 28, 2014 I think I am good on the casting holes??? Link to comment Share on other sites More sharing options...
old-tank Posted May 28, 2014 Share Posted May 28, 2014 After you are satisfied that all the air has been bled out, rapidly pump the brake pedal about 10 times. If you get even a little pedal that holds, there is still air in the system. If still no pedal, replace the MC. Link to comment Share on other sites More sharing options...
rapidride2 Posted May 28, 2014 Author Share Posted May 28, 2014 After you are satisfied that all the air has been bled out, rapidly pump the brake pedal about 10 times. If you get even a little pedal that holds, there is still air in the system. If still no pedal, replace the MC.I did that quickly up to 10-15x twice. Absolutely no dice. I was wanting to place a gauge on the master cylinder to see what pressure I have.Looks like i'll be calling Apple Hydraulics tomorrow. I hope this doesn't get ugly. Link to comment Share on other sites More sharing options...
MrEarl Posted May 28, 2014 Share Posted May 28, 2014 I hope this doesn't get ugly.Me too... Link to comment Share on other sites More sharing options...
rapidride2 Posted May 28, 2014 Author Share Posted May 28, 2014 I'm going to plug the master cylinder and see if my pedal firms up due to a 'dead head' blockage. If it's still a soft pedal then I'll know it's the master cylinder at fault bypassing internally. Link to comment Share on other sites More sharing options...
Bhigdog Posted May 28, 2014 Share Posted May 28, 2014 I HATE brakes.................Bob Link to comment Share on other sites More sharing options...
rapidride2 Posted May 28, 2014 Author Share Posted May 28, 2014 Today after work I installed a 5/16'' inverted flare plug into my master cylinder and the pedal was rock hard! This tells me the master cylinder isn't bypassing internally. I guess i need to start leak checking all my fittings & flares....I don't have any visual leaks? Fun? Nope... Link to comment Share on other sites More sharing options...
JohnD1956 Posted May 28, 2014 Share Posted May 28, 2014 If your reservoir is not depleated, I would try adjusting the brakes again and tightening till they were stopping the brake drum, then backing off 15 clicks. Link to comment Share on other sites More sharing options...
Bob Engle Posted May 31, 2014 Share Posted May 31, 2014 You didn't by chance get some of those Argentine brake hoses that expand under pressure. I only buy from Brake hoses Unlimited as they meet DOT specs and only use braided line that is rubber coated to look original. The vacuum bleeders can suck air through the threads of the bleeder valve and not pull enough to get the air out. Pressure bleeding is the best way. On cars with the master cylinder on the firewall you can gravity bleed by letting the bleeder valve open for an hour or two. Don't let the Master cylinder reservoir go empty.Bob Engle Link to comment Share on other sites More sharing options...
rapidride2 Posted May 31, 2014 Author Share Posted May 31, 2014 You didn't by chance get some of those Argentine brake hoses that expand under pressure. I only buy from Brake hoses Unlimited ey meet DOT specs and only use braided line that is rubber coated to look original. The vacuum bleeders can suck air through the threads of the bleeder valve and not pull enough to get the air out. Pressure bleeding is the best way. On cars with the master cylinder on the firewall you can gravity bleed by letting the bleeder valve open for@DJ_YG an hour or two. Don't let the Master cylinder reservoir go empty.Bob EngleStill having issues. I bought raybestos " made in china" brake hoses. I have since plugged each of my octagonal proportioning valve ports to narrow down the location of my issue.First I plugged my master cylinder itself.... rock hard pedal so it is deemed to be working correctly. Secondly I plugged both front brake ports and ran fluid just to my rear brakes..... Again a solid pedal.Then I moved to the front brakes after bleeding them several times I simply cannot achieve a firm pedal. Ive even isolated each of the front brakes independent of each other. The wheel cylinders are not leaking.What gives? Lol. Link to comment Share on other sites More sharing options...
rapidride2 Posted May 31, 2014 Author Share Posted May 31, 2014 (edited) Also. I gently clamped off each of my front brake hoses and with the rear brakes isolated i had a solid pedal. This tells me there are no Leake from the proportioning valve. It could be the brand new hoses?i have buddy bled and used a mityvac vacuum bleeder. Edited May 31, 2014 by rapidride2 (see edit history) Link to comment Share on other sites More sharing options...
buick man Posted June 1, 2014 Share Posted June 1, 2014 (edited) Bad front wheel cylinders? Take the front drums off and have someone hit the brake pedal. Watch as the front cylinders expand the shoes. Measure to see if you are getting full wheel cylinder piston travel. This is got to be it. ... Yes Brake Hoses Unlimited. Edited June 1, 2014 by buick man (see edit history) Link to comment Share on other sites More sharing options...
TexasJohn55 Posted June 1, 2014 Share Posted June 1, 2014 (edited) Bad front wheel cylinders? Take the front drums off and have someone hit the brake pedal. Watch as the front cylinders expand the shoes. Measure to see if you are getting full wheel cylinder piston travel. This is got to be it. ... Yes Brake Hoses Unlimited.????If that '52 does not have shrouded wheel cylinders with stop tabs, you will blow the guts out on the garage floor.The problem with low pedal and no pressure is either TOO MUCH travel, low volume capacity of master cylinder or air in the system.(or if you have a balloon for pressure line)I have seen very rough bored wheel cylinders cause the cup and piston to stick enough that it would not retract after first application. That would be obvious because the shoes would not be resting on the anchor point. Slim chance of this happening though. Edited June 1, 2014 by TexasJohn55 (see edit history) Link to comment Share on other sites More sharing options...
TexasJohn55 Posted June 1, 2014 Share Posted June 1, 2014 Try this, Adjust the front brakes up tight so you cannot rotate the wheel by hand and test the feel of the brake pedal. If you have a firm high pedal, there you go! Link to comment Share on other sites More sharing options...
Mudbone Posted June 1, 2014 Share Posted June 1, 2014 Try this, Adjust the front brakes up tight so you cannot rotate the wheel by hand and test the feel of the brake pedal. If you have a firm high pedal, there you go!Do what he said, Mud Link to comment Share on other sites More sharing options...
buick man Posted June 3, 2014 Share Posted June 3, 2014 …. Not with the brake shoes in proper position and place. Have done it many times on various vintage and newer vehicles. But i should of clarified my statement by saying not to stomp on the brake pedal but very gently have someone do it while you observe the action at the wheel. Link to comment Share on other sites More sharing options...
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