Brake issue and I am at a total loss.

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67dart_drop_top

67dart_drop_top

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I have been on this problem for over a year. Actually, it has really just taken a backseat to building my garage, but I started this nightmare over a year ago.

67 dart convertible, 273 automatic, manual drums all around. Nearly 100% stock.

I have had the car over 7 years. The brakes were never that great. I did a complete overhaul of the stock system. I did not want to change it from original. I really do not get on it much, and I am probably more careful than I need to be. So I know a lot of you will suggest that I should have upgraded, and at this point I will now agree. The reason? I cannot get a pedal when I move to bleeding the front brakes.

My main problem is that I should not have replaced the entire system all at once. I did the shoes, master cylinder, prop valve and even the lines. I just got back on the project, and I even installed a second master cylinder from NAPA. I wish I would have done one part at a time so I could troubleshoot each part; however, I exchanged my original master cylinder, and I am fairly sure the shoes or lines cannot be giving me a problem.

Now here is what happens when I bleed the brakes.
Right rear: pedal gets a little stiff
Left rear: getting better- almost 100%
Front right: starts to lose pedal
Left front: I lose the whole deal. No more pedal at all.

I repeated this process three times with this new master cylinder. And this is exactly what happened a year ago that led me to giving up and focusing on my garage and other car--a 69 Road Runner.

I do not know what I can add. I bench bled it correctly. We bled them in the correct order five or six times. We do not have a leak anywhere. I just do not know.

Any of you have any ideas?

I looked into pushrods length, but I do not see where it could be adjusted???

I even took off the plate that holds the pushrod in from the back. It resembles a gasket and is held on with two bolts. I thought maybe the pushrod was not traveling far enough back, so at that point I was willing to try anything.

I know I left something out???

At this point, I would be willing to do something I have not done in probably 20 years, and that is to let someone else work on my car. My other option is a brake upgrade if it is guaranteed to solve my problem.

Anyone not tired of reading yet? And have some advice?
 
General rambling from the old and senile.

It might be possible that you have something wrong with the master / pushrod piston. Basically you will have to carefully inspect and manually feel the pedal.

"What you want" is to be absolutely certain that the pedal / linkage / pushrod is allowing the master piston to fully return all the way to the clip retaining the piston in the bore.

I'm not "real" sure what I'd do because I've never been where you are.

One thing is to get on the adjusters and tighten up all 4 good and tight to eliminate the shoes as a problem

Another thing might be to buy some 3/16 inverted flare plugs and unions so you can cap off the lines, that is pull the lines loose where the metal lines connect to the hoses. Cap /plug off the metal lines. You should be able to bleed right there at the cap and produce a "rock hard" pedal.

I would review what you've done with / at the master for bleeding it. There is some but not great possibility that the master is defective. I'd think this is low on the list.

Detail "just how" you are bleeding. If you are somehow allowing air BACK IN when releasing the pedal, this might account for the problem.
 
Also, did you replace the drums or use the old ones? Drums if turned too large cause all sorts of problems, not the least of which is poor brake performance. This is because as you turn a drum out larger, the two circles, IE the circle which the shoes make, and the circle of the drum, become much different. The shoes now only contact in the mid-part of the shoe, using very little of the surface area.
 
How are you bleeding the system - two friends are better than one or none - and lots of brake fluid and tight shoes. It can be a nightmare. I think the lines are to blame - too many high spots for air to accumulate and not enough flow. Get friends - no radio or TV noise - make them pay attention -know what they are doing - and pump the **** out of each line - bleed the master lines at the master, bleed at the PP valve if you can get them loose, bleed front to back then back to front - test pressure again and again. Been driving mushy brakes for years - they aren't all that great to start with and not enough friends or kids willing to help bleed brakes. Promise of Beer or Treats sometimes helps. Tried all gimmiks and systems - Been there done that.
Still doing it.
Good luck.
Bcudamatt
 
Pics might help. There are many different faults that we might not see in pics.
Adjusters assembled wrong or switched left and right. The more you work the worse they get.
Grooves worn into backing plates at shoe contact pads.
Wrong wheel cylinder bore diameter or length.
If everything possible checks out OK we're back to the master cylinder.
Remand master cylinders are built from 40+ year old cores. To get a couple of bad ones in a row is possible.
 
Did you replace the rubber hoses?

They can be bad and cause problems also

I upgraded to SSBC it really is a safety thing, much better than drum brakes.
 
Sorry about the no replies. We are in the middle of Cruising the Coast, and my RR is running fine. We are going to spend a few minutes looking over a few things that were suggested, and I will repost if anything good happens.
 
try this from an old mopar guy, get an unpainted oil squirt can, fill with brake fluid. Now attach a hose to it , start furthest away from m/c, put hose on a bleeder and loosen bleeder. pump brake fluid until no air bubbles in m/c. tighten bleeder and then remove hose. Do all 4 and you should have no air left in system. don't let can run out of fluid!
I bleed clutch systems like this also.
 
Oklacarcollector offered the first response and was correct. One of the fronts was not tightened down. I have never forgotten this step before, and did not realize what could happen if I did. Now I feel both dumber and smarter.

Thanks!

And next time, I am going to try pete9857's idea with the squirt can to bleed. I have never thought of a reverse bleed process.

Thanks to all. It is really nice to have somebody in which to bounce around problems. It is extremely nice when the replies lead to solutions. Thanks again!!!
 
Glad to toss out an idea that worked for you. As I have gotten older, I find myself having to double check everything just to make sure I did it.
 
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