I fought the same things and it was just a lot of air in the system.I ended up putting speed bleeders on all my wheel cylinders and just kept working at bleeding the lines.It was great as I didn't have to worry about trying to find somebody to have the patience to pump the pedal as much as it needed.I couldn't believe how much air was in the system.I have drums on all four corners and it was important to make sure the brakes were adjusted correct as well.Now they work great.
Mack I'm not sure why, but jacking the front end up on my car helped. I think in my situation that after I replaced both hoses, the left front wheel cylinder and master cylinder, more air got into the lines. Watching the clear plastic hose attached to the drain bottle during the bleeding process, I noticed one air bubble did not move no matter how much I bled the darn thing. I tilted the line and the bubble moved. I jacked up the car leaving it that way over night. I then bled the system. I then jacked up the other end and did the same thing. I maybe going crazy but performing these tasks did help. The brake lines on the car have many bends that can trap the air. I still haven't driven the car yet. I want to make sure I get out all the air. With no emergency brake, I don't have many options if the brakes fail. Good luck! Going out to to the garage tonight.
Stupid question at this point but i here no mention if the brakes shoes are adjusted till the wheel drags.
Hey Dave, I'll try it!! It's been crazy here & my car time has disappeared this week. I'm sure you can't wait to get out on the road!! Posted using the Full Custom H.A.M.B. App!
Tedley, Yes, shoes adjusted. Brakes were working properly not long ago, lost pedal & replaced brake line that was leaking. After having replaced master/booster/cyl's. all new system at this point.... Perplexed as to why I can't get back to 100% Posted using the Full Custom H.A.M.B. App!
I have not tried deadheading yet. It's poss MC is failing although recently replaced. Posted using the Full Custom H.A.M.B. App!
Went out last night and depressed the brake pedal. It didn't go the floor. That's a good sign. Didn't have time to work on it. Have time tonight. As I stated earlier, those damn air bubbles have a long way to travel before they reach the wheel cylinders. My homemade pressure bleeder had 25 PSI. I was concerned going higher PSI would blow the seals in MC & wheel cylinders. Not a fan of this type of bleeding. Maybe I was doing it wrong. I didn't know if I should have the brake pedal depressed while pressure bleeding. Nothing was stated to depress the pedal.
no, the brake lines are "open" to the MS when the peddle is all the way up and the piston is at it's "rest" position. good luck
Only 5-10 psi is all that's needed when using a pressure bleeder, because you want volume, not pressure, to purge the air out of the system. Slowly full stroking the master cylinder while pressure bleeding helps chase air out of the master bore and provides the extra volume for a good bleed throughout the system. The use of a correct brake pressure bladder bleeder is the best way to bleed a system, other than the more complex and expensive vac/fill method most factories use. By correct, I mean a bleeder with a fluid bladder totally isolated from air, not a cheap "garden sprayer", which builds pressure from air mixed with the fluid, something you want to avoid with brake fluid!
All good points V8 Bob. The home made " garden sprayer " pressure bleeder I made was a great experiment and waste of time/money but the results speak for themselves. My homemade bleeder allowed air from the container & lines to be mixed with the fluid. I should have bled the pressure bleeder first! LOL. I fell for it without thinking it thru.
Mack It appears I got my brakes back. Took the jalopy out this morning on a 20 miles drive. Felt GREAT! Blew a fuse on the electric fan going back. Not sure why that happened. Didn't spoil the drive. Let us know if you got your brake issue resolved.
One way I use to bleed brakes when there is a lot of air in them... helper required and takes some verbal coordination. One person in the car, one at the farthest wheel from MC. Open bleeder depress pedal and hold (slowly and with light pressure until it reaches the floor) close bleeder release pedal repeat this several times Test pedal by pressing on it. If you can pump it a time or two and it gets better... you still have air (or not enough drag on the shoes) Repeat the bleeding like this, going from wheel to wheel and some times back to the beginning at the farthest wheel. Compair how much pressure you are getting at each wheel also.... make sure your helper uses the same amount of pressure when pushing the pedal down to make this easier to tell. I have bled brakes on a car for an hour or better some times to get all of the air out.
Dave29 AWESOME MAN!!!!! I bet that drive was incredible!! I will keep you posted on progress here. Tomm may be the day!! Mack Posted using the Full Custom H.A.M.B. App!
Burnt Hills? We gotta meet up sometime, I'm nearby in schenectady. My car is over at Devine's Auto shop on Albany Street if you come over to this area sometime within the next few days! My brakes have been funny too...they were bled, all new lines, rebuilt MC, etc..still manual brakes. For no reason they went. I topped off my brake fluid and pushed up the locking clip inside the rubber boot behind the MC, that helped. I believe I have to take it off, adjust it, and press it all back in. That gave me pressure back. Perhaps it's the same with yours? Keep us posted...
56Pontiacpiano, Hey man, schenectady!! Sounds good! I may shoot over that way this eve. Posted using the Full Custom H.A.M.B. App!
Ok, i deadheaded the MC. Only getting pressure from front. Rear-nothing. Pedal to the floor. So, returned MC only 2 months old. New one tomm afternoon. Also installed speed bleeders.... Let's see if we're closing in on this.... Thanks all!! Posted using the Full Custom H.A.M.B. App!
What MC did the PO install? If it is the dual circuit MC (two chambers in the reservoir, as opposed to the "fruit jar" type master)? If dual circuit, is there a combination valve installed (usually a brass piece with 4 tube connections)? If so, is it a Drum/Drum unit? I ask, as I saw someone asked (earlier) what residual pressure valve(s) you have installed currently (10Lb for drums) and I didn't see a reply. If the MC is set up for Drum brakes, it should have them, if they are not, you need some (Drum/Drum combination valve should have them, without them wheel cylinder pistons can retract too far, causing the symptom you describe). When you get the new master, check how far the pin sticks out off the booster, if it's adjusted too long, it won't let the master cylinder piston return fully, which can cause the same greif as a sticking pedal (very similar to what you describe).
It's drums front/back with a '72 chevelle dual MC, no residual valve. See, I had a great pedal and brakes were super before the line started leaking. Only difference is a replace brake line that takes a slightly longer route to the MC. Posted using the Full Custom H.A.M.B. App!
some additional info http://mbmbrakeboosters.com/index.php?option=com_content&view=category&layout=blog&id=8&Itemid=16 http://www.amazon.com/Brake-Handbook-Fred-Puhn/dp/0895862328 good luck
Ok, new MC bench bled and installed, speed bleeders installed. Wondering about the residual valve still? Kersplat, going to re-read the info you sent now.... Posted using the Full Custom H.A.M.B. App!
Ok, re-read about RPV's and not certain if new MC has them already. I'll check with part store. But, sounds like a no brainer to install if the '72 chevy MC doesn't have already. Posted using the Full Custom H.A.M.B. App!
Where are you getting the vacuum for your brake booster? You need an average of 16lbs of vacuum for the booster to function properly.
I had an old single resivior master cylinder with drums front & rear on my mercury. I changed to a dual one still with drums. Should I change the pedal rod between the vacuum booster & the M/C? I seem to have a low pedal with lots of travel.
Br8nek, vacc is from the manifold. Unsure of amnt. The booster was working great before changing a leaking line. Posted using the Full Custom H.A.M.B. App!
Ok, frustration may have set in a little... Lol. No fluid from the pass rear bleeder. Nothing, pedal being pumped & no fluid. How come? Posted using the Full Custom H.A.M.B. App!
How is the line routed from the master to the right rear? Is it separate from the line to the left rear, or does it T off from there (ie one line from the master to the right rear, or one line to the axle, a T then one to the right rear, the other to the left)? Are you getting fluid to the left wheel cylinder? If the line is common to a T somewhere (I suspect it is) and you have no fluid from either side you may have the pin on the booster too long, to test that, try loosening the nuts on the booster that hold the master on so the master will move forward slightly (1/16" - 1/8"). If that helps, it's the booster pin (they are usually adjustable). If not, I suppose you could have some sort of blockage in there, how much of the brake plumbing did the PO change when he installed the booster? IIRC you haven't replaced the rear wheel cylinders?
It's "T'd on the pass side. I did not check the dr side yet. Posted using the Full Custom H.A.M.B. App!
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