Brake system issues remain - next steps??

[Ron H]

A lot of good advice on these posts and know you have a lot of knowledge. I also know how damn frustrating brakes can be. I think as has been touched on – a possible diff with M/C’s can be the throw (depth) of the plunger and return. There should be a bit of free play with the pedal in its home position to assure no possible pre-activation of the M/C. Not binding against the brake light switch. Other check is how deep the piston is entering the M/C. No doubt you know the diff btw a power vs manual brake M/C. Also as mentioned, if there’s any hang up with the brakes not-disengaging this can cause pedal sink. Both issues I mention were problems I had.
Not to insult your intelligence; just a few tidbits that come to mind.

 

[moparedtn]

A lot of good advice on these posts and know you have a lot of knowledge. I also know how damn frustrating brakes can be. I think as has been touched on – a possible diff with M/C’s can be the throw (depth) of the plunger and return. There should be a bit of free play with the pedal in its home position to assure no possible pre-activation of the M/C. Not binding against the brake light switch. Other check is how deep the piston is entering the M/C. No doubt you know the diff btw a power vs manual brake M/C. Also as mentioned, if there’s any hang up with the brakes not-disengaging this can cause pedal sink. Both issues I mention were problems I had.
Not to insult your intelligence; just a few tidbits that come to mind.

Thank you kindly as always sir - but I'm specifically asking if anyone knows of any difference(s) between the
original style drum master cylinder and the only one available from the aftermarket these days (other than the
lids, of course) as pictured??

Further - as far as replacement front lines go - are there actually a bunch of different routings/locations on these
cars as built, like the vendors claim now?
Further - what were the original lines made of and do I actually need stainless?

 

[4406bbl]

You do not need stainless, no idea on the master but it kinda can't cause a side to side pull issue. The wheel cylinders, I assume are new and have been disassembled to be sure that are the same exact size bore inside. A 1/32" difference would be a problem.

 

[threewood]

I'm interested in knowing what others say. I have to pull up on the brake pedal to release the brakes.

I ran into this issue with the Dr. Diff front disc upgrade kit. Plastic master cylinder reservoir using my factory push rod. I don't believe the internal springs are heavy enough to reset the brake pedal. I ended up adding an external spring to pull pedal back up. No issues since.

 

[threewood]

Ed, with one side locking prematurely I would look at the proportioning valve. The M.C. has an outlet for front and and outlet for rear. So it goes to reason that the same pressure is leaving the M.C. outlet and getting out of balance further down the line. Or possibly a stuck or dragging wheel cylinder.

 

[khryslerkid]

Ed, with one side locking prematurely I would look at the proportioning valve. The M.C. has an outlet for front and and outlet for rear. So it goes to reason that the same pressure is leaving the M.C. outlet and getting out of balance further down the line. Or possibly a stuck or dragging wheel cylinder.

I was thinking the proportioning valve also. Am I wrong in stating it devides left and right front wheels?

Normally when you have a brake/wheel locking up, it's the opposite side that's not working which gives you the impression it's the wheel that's locking/pulling at fault. If the wheel that's locking is running hot and dragging then you can have a wheel cylinder or caliper hanging up and not releasing. Or maybe the proportioning valve?

 

[Budnicks]

www.therammanINC.com

 

[moparedtn]

@4406bbl @threewood @khryslerkid
I'm looking at the master cylinder because I've never liked the pedal I get from this one.
The distribution block is definitely a suspect; as I've repeatedly mentioned, it's original to
the car, as are the front hard lines....
This is the point I've reached in figuring this thing out, hence the questions.
Thanks!

 

[khryslerkid]

@4406bbl @threewood @khryslerkid
I'm looking at the master cylinder because I've never liked the pedal I get from this one.
The distribution block is definitely a suspect; as I've repeatedly mentioned, it's original to
the car, as are the front hard lines....
This is the point I've reached in figuring this thing out, hence the questions.
Thanks!

If you don't have enough play, just a little, in the pushrod, it could cause problems not letting the master cylinder piston return far enough.

(Ed says..."Don't make me get up under that dash again! "

 

[moparedtn]

If you don't have enough play, just a little, in the pushrod, it could cause problems not letting the master cylinder piston return far enough.

(Ed says..."Don't make me get up under that dash again! "

Pedal travel/adjustment seems pretty close - it's the "can't get rid of the mushy" part I'm done with.

 

[MoparGuy68]

Further - what were the original lines made of and do I actually need stainless?

I’m certain the OEM lines have some lead in them, as they can be bent fairly easily. I did not get Stainless because I was told it is much harder to bend and tweak. Even though I purchased a set of pre-bent OEM lines from Dr. Diff, ALL of them needed some bending and tweaking to fit my car properly.

For me I shudder at the thought of trying to make all those adjustments on stainless lines. Even with the non-stainless OEM I had difficulty getting the shortest line bent to fit properly. It is the one that connects the proportioning block to the metering block on my system.

 

[4406bbl]

Stainless line bends just as easy as steel. The problem is sometimes it likes to leak at the brass fittings/flares at master, hoses brake line tees, anything brass as th line is harder. It helps to start with all new parts, lube well with brake fluid, and what I do is buy some stainless couplers on ebay tighten the flares in those a few times to form the flare then install in brass. The ones I can reach with a flare tool I just use that, but sometimes the flare nut cannot be backed off. Brass couplers only last for 1-2 flares, stainless last longer. Anyway if you want stainless this is one way to get it leak free.

 

[ruffcut]

Ed, this is the mastercycylinder I used from Summit Racing Inc. You'll notice it has a larger capacity for disc brakes, and that's what I installed on the front of my 68 RR.(manual disc)
So, if your present MC is not returning the pedal, I think it's weak at best, and should be replaced, even though general thought is that's not the culprit as for the grabbing brake on just one side.
Sure wish I could be there to help figure this out!
ruffcut(Dave)

 

[ruffcut]

Ed, even though you replaced the brake hoses, doesn't mean one is not defective.

 

[moparedtn]

Ed, this is the mastercycylinder I used from Summit Racing Inc. You'll notice it has a larger capacity for disc brakes, and that's what I installed on the front of my 68 RR.(manual disc)
So, if your present MC is not returning the pedal, I think it's weak at best, and should be replaced, even though general thought is that's not the culprit as for the grabbing brake on just one side.
Sure wish I could be there to help figure this out!
ruffcut(Dave)
View attachment 1285165

Thanks as always, Dave - but it was someone else sort of highjacking the thread who had the "pedal
not returning" problem. This one does fine in that regard, anyways...

 

[moparedtn]

Ed, even though you replaced the brake hoses, doesn't mean one is not defective.

True, but I'd assume I'd see some sort of evidence of that at bleeding time - and there's none.
Thanks again!

 

[moparedtn]

Status Update 5/15:
No, no actual work has taken place since the beginning of this thread.
I didn't want to start throwing parts at it until I got a plan settled that a)made logical sense
and b)actually had a chance of improving what I have now (vs. the looming disc swap/last resort).
In that pursuit:
1 - Given that EVERYTHING that could be swapped side to side HAS already been tried, that rules
out the shoes, hardware and drums themselves. No changes planned with either.

2 - The only assumed original, unreplaced pieces of the system left on the car are the front lines and distribution
block; BOTH of those are going to be replaced/serviced as part of this plan, done deal.

3 - The master cylinder is a rebuilt but of dubious nature, always has been. Looks wrong on the car, acts
spongy I don't care how many times it's all been bled - it's going to get replaced as well.

4 - The brand new (but aftermarket) wheel cylinders can't be swapped side to side of course - but there
IS something eating at the back of my mind about them:
They're two different brands and although what research I could do online indicated they're correct (from
manufacturers' archives and such), something is telling me it's worth fetching a new pair from RockAuto
or wherever (yes, that means Chinesium) to give them a whirl as well, to ELIMINATE the wheel cylinders
as a possible cause (or what the heck, maybe not?). Those get changed just to eliminate them as well....

That's where we are with this mess. The usual cobble up money and get to buyin' part commences now,
albeit hampered by my wife having to travel to look after her mother, who is not faring well at all right now.
Priorities....
Been there, all mine are gone now. I can relate. I can wait.
Thanks y'all!

 

[super-bee_ski]

www.therammanINC.com

Great product line Budnicks

 

[super-bee_ski]

Ed,
Hope things work out
I'm watching thread so I can learn
Great support form all members here...

 

[furyus]

I would replace the M/C with one for manual disc. It will work fine, and then you won't need to go through that again when you go to disc. I bought new wheel cylinders for my Dart. Couldn't get good pedal. I ended up peeling the wheel cylinder boot back, and saw where fluid was leaking past the piston. I put the old one back on. Sorry, I don't know the difference between the drum masters.