Moparts
Brake pedal "meh" thinking about braided lines.
Posted By: gdonovan
Brake pedal "meh" thinking about braided lines. - 03/18/14 01:16 AM
Converted my GTX over to 73-76 Dart/Duster disc brakes this weekend and the brake pedal seems like weak sauce. Rebuilt Autozone calipers, Wagner Thermoquiet semi-metalic pads, new rotors and new Wagner brake hoses.
Power bled the calipers with a electric vacuum pump and the old fashion way with an assistant. Clear bleeder hose shows nice clean fluid with no bubbles. Calipers are pointing the correct direction (bleeders UP)
Car has a '74 Disc brake master cylinder with no booster which was on the car when I was running the 11" drums and works fine. If I turn the line lock on and then hit the pedal its iron. If I heave on the pedal with the line lock off the pedal will go 5 or 6 inches down.
Driving the car is a pleasure, I can hit the brakes and the car doesn't dive about like it did with the old drum setup. The car doesn't lock up the brakes but I can stop in a hurry if I bury the pedal as hard as I can.
Admittedly, I only have about 40 miles on the brakes and perhaps the pads still need to be fully burnished in. I'll continue to drive the car and work the pads in but it seems to me even so the pedal could be better. I ran my Dart with the same setup decades ago and don't recall the pedal being this soft with a manual disc setup.
Inline Tube makes braided hoses for the front, good investment? For $60 shipped for the pair chump change that I don't mind spending.
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 01:53 AM
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Inline Tube makes braided hoses for the front, good investment?
No cuz there is still an issue someplace that needs to be dealt with. I'd think the problem is likely air. I'd screw a pair of brass inverted flare plugs from the Edelman parts cabinet at your parts house (they're cheap & you will reuse em) into the M/C ports & if the M/C is bled out (& good & it was good before)) the pedal will be rock hard with virtually no travel. then uncap/hookup the rear drums & bleed them out but first pulling the E brake on will tell you if it is a rear lining clearance problem instead of air. When good there uncap/hookup the fronts & work on them. Some calipers are hard to bleed & pumping the pedal 3 times then having a helper opening the bleeder at just the right moment (on the 4th downstroke/perfect verbal timing needed) helps sometime to agitate the mixture & drive the air out. On some cases you need to take the calipers off & block the piston & hold them at the right angle so they bleed out. The bleeder might need to be at 12 o'clock exactly but the passage where it meets the bore must be at 12 0'clock cuz that's as you know where the air will rise to but the agitation helps with that.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:05 AM
I'm 100% positive there is no air in the system, even went as far is to put 26 inches of vacuum on the caliper bleeders and pull a half quart of fluid out on each side.
And then manual bled them with an assistant for good measure.
The rears and master cylinder has already been eliminated as the issue, the line lock is on the front circuit after the master cylinder.
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:07 AM
when it acts up it will not pump up at all?
Posted By: ahy
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:11 AM
The braided hoses help firm pedal feel a little. I like and use them. That said, I think you have more sponginess than can be explained by the hoses unless you have a weak or defective hose (which may be). 5-6" of pedal travel is a lot of difference line lock on and off.
Posted By: 340SHORTY
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:14 AM
did you put a proportioning valve in place of the distribition block ?
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:16 AM
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when it acts up it will not pump up at all?
It doesn't "pump up" like a bad master or even like there is air in the system. If you let the pedal set it acts the same. Pumping the brake has no effect on the pedal height or stopping power.
It feels like something is flexing, like a hose is expanding or the pads are really not bedded in. I have had cars with crappy brake jobs sort of feel this way (heavy grooves on the rotors with new pads for example)
The pedal is in the normal position, it won't drop all the way to the floor but you have to really dig in to get the car to stop with authority and it feels soft. Only way I can think to describe it.
Activating the line lock makes the pedal virtually immobile during braking. I tried it on a road test to check the rears and they are working, the pedal is stout so what ever is going on is related to the calipers, pads or hoses on the other side of the line lock.
The master was not allowed to bleed out while I swapped the brakes over, didn't take much time in a shop with air and a lift with everything ready to go months ago.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:28 AM
Like I said, its possible the pads are not bedded in. Maybe the compound is a bad match for the car without a brake booster. The rotors are new '78 big 11.75" rotors with the Duster slider calipers, one would have thought it will stop better. It did improve somewhat after a long roadtest with lots of heavy braking with cool down between applications.
P.S. the Master cylinder is the 1-1/32" unit if curious.
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:29 AM
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but you have to really dig in to get the car to stop with authority and it feels soft.
Alright, I'd take off the front wheels & have a helper work the pedal as you checkout the hoses/pads/calipers for anything wonky. I did have the exact symptom on the stock car once & it was partial blocked flow to the front calipers from using the wrong braided hoses to the calipers that were bent at a bit too much of an angle & was restricting the flow. I had to stand on the pedal to get brakes. EDIT The more I think about it the more I think it's a mechanical hangup with the caliper/pad action
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:39 AM
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did you put a proportioning valve in place of the distribition block ?
Actually I did not- This would be a concern if the rear wheels are locking up and then I would install an adjustable one for the rear brakes as outlined here: http://www.moparaction.com/Tech/archive/disc-main.html
I have done disc swaps before and would rather change about the pads, shoes and wheel cylinders to get the brake bias I'm looking for before installing an adjustable bias valve.
Since I'm not getting any locking action on the front end I'm not concerned with that being an issue at the moment.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:43 AM
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Alright, I'd take off the front wheels & have a helper work the pedal as you checkout the hoses/pads/calipers for anything wonky.
That is the plan for tomorrow.
I even jacked up the passenger side of the car only to make sure the pass brake caliper was the highest part of the system when bleeding it, made no difference.
I'm just looking to eliminate possible issues, I'll be real curious what those brake hoses look like tomorrow. They were old Wagner stock I had on the shelf for three years, I wonder if they can get funky from sitting?
Posted By: Supercuda
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:45 AM
I suggest you look into what the factory combination valve does before you dismiss having one or think just putting an aftermarket adjustable proportioning valve in is the same.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:47 AM
Quote:
EDIT The more I think about it the more I think it's a mechanical hangup with the caliper/pad action
Possible- Everything looked good and flat, pads were sprayed, tabs tweaked so they were snug on the calipers, etc. Possible one of the calipers is warped? If so you think the car would pull in one direction or another...
Hmm.. If need be, I can steal the calipers off the Duster since they are known good units.
Posted By: Todd
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:49 AM
Make sure none of the pistons in the calipers are retracting to far after the pedal is released.
Had a brand new one do that. Turned out the seal bad and was pulling the piston back 1/8".
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 02:54 AM
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I suggest you look into what the factory combination valve does before you dismiss having one or think just putting an aftermarket adjustable proportioning valve in is the same.
The '70 GTX drum/drum unit is just a distribution block.
A disc brake car has a prop valve that regulates how much pressure the rear sees. For this application the current block is just fine, the problem is I'm not getting enough force on the FRONTS, not too much on the rears.
I need to find out why the fronts are acting as they are, the current block being used will have no impact on the issue.
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 03:30 AM
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pads were sprayed,
"disc brake quiet" on the back side of the pads?
Posted By: skicker
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 03:46 AM
Is it possible the 1 1/32" MC does not provide the volume of fluid needed to make the calipers more aggressive?? You said it used to dive with the drums, which to me means it had substantial front brake. Calipers do require more fluid volume than a wheel cylinder don't they?
My 70 Satellite has the same issue. It has a long pedal on the first pump but it stops fine. Its been bled and bled with no difference. Makes my think maybe the M/C bore is the culprit. The line lock comment makes sense when mine is on and you touch the pedal there is nothing but hard line in the system and no way for the pedal to move whatsoever. This is normal.
Posted By: west
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 09:29 AM
Quote:
Make sure none of the pistons in the calipers are retracting to far after the pedal is released.
Had a brand new one do that. Turned out the seal bad and was pulling the piston back 1/8".
I would look into this as well.
A residual valve would fix the problem. Either way, the braided lines won't correct the problem.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 10:38 AM
Quote:
Quote:
pads were sprayed,
"disc brake quiet" on the back side of the pads?
Yes
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 10:53 AM
Quote:
Is it possible the 1 1/32" MC does not provide the volume of fluid needed to make the calipers more aggressive?? You said it used to dive with the drums, which to me means it had substantial front brake. Calipers do require more fluid volume than a wheel cylinder don't they?
Car already had a disc brake master cylinder on it for the last two years. It is a standard disc brake unit used in millions of Darts, Dusters, Valiants, 71-74.
A 1" bore would increase the pressure but at the expense of more pedal travel.
The pedal is not solid (unless the line lock is on) as it should be and its taking excessive pedal pressure and travel to get the car to stop quickly.
After sleeping on it I'm convinced something is flexing. Maybe one of the caliper slides are tweaked, seals are junk or hoses are no good.
I can swap parts off the Duster, heck I can swap the calipers, brackets, rotors and pads over if need be in an effort to isolate the problem.
Posted By: therocks
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 01:48 PM
get a reman master for a 70 C body with disc/drums.They are all we run.Pedal is always right there.That and make sure the rears are adjusted up.Rocky
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 01:52 PM
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That and make sure the rears are adjusted up.Rocky
Rears are spot on.
Tonight I may bypass the calipers by blocking the lines at the bango fittings. If the pedal still has a lot of "travel" then it has to be the two flex lines, if not I'll have to look close at the calipers and pads.
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 03:01 PM
i had about an inch more pedal travel than i was happy with on my last conversion to discs.no amount of bleeding or adjustment helped but i did have good braking.
continued driving over the first few weeks brought the pedal up to a satisfactory position.
i suspect that with use,the pistons worked there way closer and retracted less but don't know for sure.
a pedal ratio of 1:6 with a 1" master,2" of pedal travel would not move a couple of 2.75" caliper pistons very far
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 03:31 PM
Quote:
continued driving over the first few weeks brought the pedal up to a satisfactory position.
I'm tempted to do just that but it will cost me nothing but a little time to narrow down the possible reasons.
I still think $60 isn't a bad investment for the braided hoses.
Posted By: Supercuda
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 04:56 PM
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Quote:
I suggest you look into what the factory combination valve does before you dismiss having one or think just putting an aftermarket adjustable proportioning valve in is the same.
The '70 GTX drum/drum unit is just a distribution block.
A disc brake car has a prop valve that regulates how much pressure the rear sees. For this application the current block is just fine, the problem is I'm not getting enough force on the FRONTS, not too much on the rears.
I am not talking about your current problems, other than that problem of thinking you do not need a factory style combination valve. I highly suggest you read up on what they do and why, you're a smart fellow and unlike some here ought to be able to understand it's function.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 05:16 PM
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I highly suggest you read up on what they do and why, you're a smart fellow and unlike some here ought to be able to understand it's function.
I have, there are several threads on the subject.
https://board.moparts.org/ubbthreads/show...amp;Search=true
Unless I'm locking up the rear brakes (which I'm not at the moment, they are deliberately undersize at 10") a distribution block is just fine. It isn't the cause of the current issue.
Now if I was locking up the rears all the time I would agree with you.
BTW as an aside? My Reliant doesn't even have a valve, no rear brakes! With 75 pounds on each rear tire they would just lock up instantly. The master on that car does the left and right wheel separately.
Posted By: DoctorDiff
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 05:18 PM
Did you confirm the master cylinder and caliper bore sizes?
If you installed '76 and newer slider calipers (2.75" bore), coupled with a '73-'75 A-body POWER (15/16" bore) master cylinder, you will experience long, light pedal travel.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 05:33 PM
Quote:
Did you confirm the master cylinder and caliper bore sizes?
If you installed '76 and newer slider calipers (2.75" bore), coupled with a '73-'75 A-body POWER (15/16" bore) master cylinder, you will experience long, light pedal travel.
The master I'm working off the part number that was ordered for my '74 Duster with disc brakes, same for the calipers.
The master is *suppose* to be 1 1/32" and worked fine with the drum brakes. It takes a stout leg to operate a power master cylinder without a booster but I'm use to a clutch pedal with big spring rates so not a big deal to me.
The pedal feels solid, not light at all just spongy. Almost like the pedal linkage is flexing but that has already been eliminated by turning the line lock on.
I'll take some measurements tonight if you like, have to check the casting for numbers though since the master is secured from the inside.
Posted By: stumpy
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 06:09 PM
Seems like your hung up on installing braided lines. Just do it and then you can go about fixing the original problem.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 06:17 PM
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Seems like your hung up on installing braided lines.
Not necessarily, it does seem logical that they would flex much less than factory rubber lines and that does *feel like* what the problem is. I'll know more tonight when I block the calipers off.
Posted By: barracuda7199
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 06:24 PM
A new aluminum 1 1/32 master cylinder with adapter from doctor diff fixed your same problem on my car. Stops far better than it ever has and has the best pedal it ever had. His masters are going on all our cars from here on out.
Posted By: AndyF
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 08:15 PM
I'd be surprised if you feel a difference between OEM hoses and SST hoses.
The main reason to run SST hoses is either looks, or because you can't find a stock hose that fits/works for a custom brake setup.
SST hoses aren't really a performance upgrade even though they look like they are.
Posted By: TJP
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 09:24 PM
I am suspecting that you may have air in the front (disc) portion of the system or master. WHY ???? you indicate that the pedal is rock hard with little movement when the line lock is engaged which effectively blocks the front lines off.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 09:41 PM
Quote:
I am suspecting that you may have air in the front (disc) portion of the system or master.
That was my first thought which is why I vacuum bled them twice, had a helper bled them twice and even jacked up the car on one side to raise the caliper higher. And when I say vacuum pump, I mean a $250 electric pump with clear reservoir and lines I use just for bleeding brakes when help isn't about, it does a superb job.
Not my first rodeo, I have done thousands of brake jobs over the last 30 years professionally. Air was the first thing I thought of and did my best to eliminate it as a possibility.
Usually if you have air in the system you can pump the pedal and it will come up, this doesn't act that way.
The best description is new pads on a beat grooved rotor if you have ever done it. Its a spongy "not right" feeling.
Heading out to the garage now after a java infusion, pics later.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 10:51 PM
Pulled the pads off and it looks like they had uneven contact with the rotor, will head out to take a pic.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 11:03 PM
You can clearly see three spots on the pads where they were not making full contact. Either the pads were not flat out of the box or the caliper and or slides are not totally square to the rotor face.
Posted By: Twostick
Re: Brake pedal "meh" thinking about braided lines. - 03/18/14 11:28 PM
Can you seal off the top of the master and then put a vacuum on the reservoir? Any air hiding in the system will have no choice but to go to the top.
Also if you vac it out and close the valve you can see if it will hold a vacuum. If it won't you will have found out why your pedal is spongy. Then you get the fun of figuring out which seal can hold fluid under pressure but not air from the lack of it.
Kevin
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 12:07 AM
So I'm digging around further and here is what I found- When there is two chunks of steel in the calipers I can clearly see the pistons move out 1/8" and then back in about the same amount when the pedal is released.
This jarred a memory- Is there not suppose to be a residual check valve built into the master cylinder that leaves a pound or three of pressure in the lines for disc brakes? Or do I have it backwards, for drum brakes?
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 01:00 AM
In for the night, I can't get a good seal on the banjo fittings. Try again tomorrow..
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 02:20 AM
no check or residual valves for discs...
Posted By: Telvis
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 03:03 AM
I had a similar problem with a rear disc conversion. I have a pressure bleeder and ran about 2 qts. of brake fluid trying to get the pedal firm with no luck. I worked for a week every night trying to figure out why the brakes wouldn't pump up. as a last ditch measure I took off the calipers and put the bleeders at 12 o clock (they were at about 10 o clock on the brackets). I bled them again in that position and it did the trick. I would have bet a months pay that they were fully bled with my pressure bleeder but there was air trapped in the system. I think someone already said it could be the issue. I would give it a shot before replacing anything. FYI... Make sure you put a clamp on the piston before you bleed the caliper off the rotor. Your piton will pop out otherwise. Don't ask me how I know that...
Posted By: west
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 03:09 AM
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no check or residual valves for discs...
That is incorrect.
Posted By: TJP
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 03:54 AM
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Quote:
no check or residual valves for discs...
That is incorrect.
I'll agree but the OP appears to have all the answers having done thousands of brake jobs throughout his professional career. "NOT his first RODEO". OK I'm done here. 
Posted By: west
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 04:25 AM
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 10:59 AM
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Quote:
no check or residual valves for discs...
That is incorrect.
If my dusty memory serves me right on some master cylinders they built in and are where the line screws in.
I have included a picture from the factory service manual, drum brake only,
For the hell of it I'll bleed the calipers at 12 o'clock, they are already off with blocks in them.
Oh and we did bled the system again last night, at the master, line lock and calipers and it made no difference. Pedal still had a measured 5" drop when heaving on the brakes.
For those interested in the lines, I observed no measurable swelling. They would "squirm" a little bit under hard application but thats it.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 11:22 AM
Quote:
Quote:
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no check or residual valves for discs...
That is incorrect.
I'll agree but the OP appears to have all the answers having done thousands of brake jobs throughout his professional career. "NOT his first RODEO". OK I'm done here.
You opined there was air in the system even though there isn't a single indication there is. No bubbles in the system, no surge in the master when the pedal is released and the pedal doesn't pump up to a higher/better location. I've done everything short of rotate the car 90 degree while bleeding. (have had at 45 degrees though) it hasn't changed at all.
No opinion on the unevenly worn pads? There is an problem right there that will cause the described issue even though I don't think that is it totally.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 11:30 AM
For those leaning towards the prop valve, here is the section where the manual clearly states its for metering pressure to the rear brakes to prevent lockup.
I have done this swap several times with great success, I'm starting to think I have a defective master since the rest of the system looks to be up to snuff. Stranger things have happened. I have a lightweight manual master with adapter on my Dart, I'll try swapping it and see what happens.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 11:38 AM
Quote:
Can you seal off the top of the master and then put a vacuum on the reservoir?
I could fabricate something, I might try it if the other master I have doesn't work out. I really hate swapping out a manual master, I'm not as flexible as I use to be after pulling wrenches for 31 years.
Posted By: slantzilla
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 12:05 PM
Don't be surprised if your Otterzone rebuilt calipers are junk. I had the same issue on my old Duster and ended up changing calipers.
Had the same experiences with an AZ master. Took 3 of them to get a good one.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 12:14 PM
Quote:
Don't be surprised if your Otterzone rebuilt calipers are junk. I had the same issue on my old Duster and ended up changing calipers.
At this point the only thing I'm sure that is good is the darn hoses!
Posted By: Supercuda
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 02:57 PM
Quote:
For those leaning towards the prop valve, here is the section where the manual clearly states its for metering pressure to the rear brakes to prevent lockup. /quote]
I take back my smart comment.
I have repeatedly told you that my comments on the combination valve have NOTHING to do with your current issues. What I have said is that not running one is a bad idea and if you actually COMPREHENDED what both myself AND the FSM is saying you'd know why. BUt like others have said, you know it all.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 03:05 PM
Quote:
What I have said is that not running one is a bad idea and if you actually COMPREHENDED what both myself AND the FSM is saying you'd know why. BUt like others have said, you know it all.
"I suggest you look into what the factory combination valve does before you dismiss having one or think just putting an aftermarket adjustable proportioning valve in is the same. "
The factory combination valve does nothing but regulate the amount of pressure to the REAR brakes and provide a location for the brake warning pressure switch.
If I had a problem with the REAR brakes not functioning correctly I'd look into it. Since the problem is with the FRONTS not working effectively its something that can be excluded for the moment.
Opinion on the unevenly worn pads?
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 04:03 PM
Gdonovan you sure are handling the haters on here much better than I would (or have)
. It's always a pain when peoples' Mammas dont tuck em in at night then we have to deal with their attitudes. After rereading your OP, with the line lock in the line to the front discs when it's on the pedal is rock solid which tells me that the M/C is good (& it was before) & the rear drum half is good & that the problem is downstream from the line lock which is the front discs. I bet it is the calipers
& rebuilt ones are cheap. Keep us updated
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 05:09 PM
why do you suspect calipers?
..the ops calipers are working and he has described no leaks.
..how did your rebuilt units fail?
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 06:12 PM
Quote:
why do you suspect calipers?
I suspect ANY of the new parts myself. Some caliper seals are directional, maybe the installer bungled it and thats why they are retracting 1/8" when you lift off the brake. I didn't think the mopar single piston units were that way but its been a decades since I have rebuilt a pair. Maybe the Advance Auto caliper rebuilder is using kits from China! 
Time permitting the easy thing to do is swap them off my Duster, known good units.
Has to be hoses or calipers. While the pads look funky they do look like there were starting to shape themselves flat and the odd pedal was still there when I substituted blocks of steel for the pads.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 06:20 PM
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Gdonovan you sure are handling the haters on here much better than I would (or have) .
Well I try to give them the benefit of the doubt, maybe I wasn't clear on some point or left some chunk of information out hence I try to be as descriptive as possible. Perhaps I didn't grasp the meaning of what one person suggested and ask to have something expanded on.
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/19/14 06:21 PM
yes,1/8 travel seems far too much.perhaps using a spacer
position those pistons further out and re assemble?
Posted By: Todd
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 12:22 AM
Quote:
yes,1/8 travel seems far too much.perhaps using a spacer
position those pistons further out and re assemble?
Spacer???
Maybe your forgetting how a disc brake caliper work
If your pistons are retracting 1/8" that's way to far.
Like I stated before the seals are pulling the pistons back to far.
They should only retract far enough to let the rotor spin without touching.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 12:40 AM
Swapped the calipers from Duster <---> GTX, noted the Duster had steel pistons while the GTX had the phenolic resin units. Both calipers had 3699963 part number cast into the back of the drivers side unit.
No road test tonight, have to be up at some ungodly hour of the morning to pull a third shift fire drill. Dinner, Justified and bed!
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 02:17 AM
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Swapped the calipers from Duster <---> No road test tonight,
We'll be waiting
Posted By: skicker
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 03:12 AM
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yes,1/8 travel seems far too much.perhaps using a spacer
position those pistons further out and re assemble?
Spacer???
Maybe your forgetting how a disc brake caliper work
If your pistons are retracting 1/8" that's way to far.
Like I stated before the seals are pulling the pistons back to far.
They should only retract far enough to let the rotor spin without touching.
I think Todd nailed this correctly with his first post. 
I have had this happen on the rear of a 4 wheel disc dirt car but have never had it on a dodge. It only stands to reason all calipers serve basically the same principle, they're just in different configurations.
Is it possibly caused by the phelonic piston rather than the steel?
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 03:31 AM
let me explain..
take the calipers off the rotors and using a "spacer" narrower than
the rotor,force the pistons further out.
re assemble such that they are only about 1/32" off the rotors.
now there will be almost no travel.
Posted By: skicker
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 03:44 AM
What is to stop them from retracting the 1/8" next time you apply the brakes? If they retract 1/8" wouldn't they retract the same each time?
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 03:50 AM
when the brakes are applied the pistons are pushed out until the pads hit the rotor,distorting the o ring.When released the rubber o ring
will go back to it's original shape,pulling the pistons back.
If the piston moved 1/32" and contacted the rotor,it will only move back 1/32" to it's original position.
Posted By: skicker
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 04:04 AM
I get what your saying. Maybe I'm just skeptical...kinda maybe wanna see it for myself type thing.
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/20/14 04:10 AM
the o ring will only distort or roll over so far and at that point the piston will start to slide through,keeping the pads close as they wear.
1/8" of travel seems eccessive and would use a lot of fluid and pedal
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/21/14 01:39 AM
A quick recap, since it looks like I found the problem.
1) Car was pulled into the garage with functioning 4 wheel drum brakes with a .960 manual disc brake master cylinder. No pedal problems.
2) In less than three hours the spindles were swapped out, new lines, rotors, reman calipers and pads were installed. The system was never allowed to bleed out.
3) Pedal quality was poor, multiple efforts to bleed out system with both helper and electric vacuum bleeder tool to no avail.
4) Swapped calipers from known good vehicle, pedal the same.
Tonight I installed a cast iron master cylinder with plastic reservoir and 2 to 4 bolt adapter from my '67 Dart (patiently waiting in the wings) which had manual disc/drum when I purchased it and it worked great. Don't even have an idea what year it is off, former owner mentioned late 80's truck and Autozone.
Did a half ass bleed with the unit in the car and then hooked up the lines. Bleed the master out again by cracking open the lines at the master with a helper.
Now I have an awesome pedal.
So, whats up with that?
Can't wait to road test, hope the ground is froze in the morning and I'll buzz it to work. Been raining here for several hours, driveway is mud pit.
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/21/14 01:48 AM
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it looks like I found the problem.
Tonight I installed a cast iron master cylinder and it worked great. Now I have an awesome pedal.
So, whats up with that?
Bad M/C or air in it or a combination of both. I'm assuming it's bore dia was not so small that it took an inordinate amount of pedal travel to fill the calipers
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/21/14 01:52 AM
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Bad M/C or air in it or a combination of both. I'm assuming it's bore dia was not so small that it took an inordinate amount of pedal travel to fill the calipers
Something funky.
I'm 100% positive there was no air in it. Pedal was great when I pulled into the garage and the system was bleed several times after in a vain attempt to isolate the problem. Pedal was great when the line lock was on! Almost like there was a bad spot/pitting in the master bore and fluid was getting by? Maybe the further travel was letting the seal to reach that part of the bore.
I didn't even do a decent bleed job tonight, it was wham bam thank you ma'm, slap it in and hit the pedal a few times. If the road test is good I'll do a proper 4 wheel bleed this weekend.
Posted By: Todd
Re: Brake pedal "meh" thinking about braided lines. - 03/21/14 02:01 AM
Posted By: skicker
Re: Brake pedal "meh" thinking about braided lines. - 03/21/14 03:44 AM
I put the 4 bolt to 2 bolt adapter on the 69 Dart. It was aluminum master cylinder with the plastic tank. I got the entire set up from Rick Ehrenberg. I have had no issues with the brakes on the Dart whatsoever. I attributed it to the fact that the 73-6 disc spindles and calipers were used with the correct distribution block for manual disc brakes. I was fortunate the donor car was also a manual disc. Maybe I should get another kit from Rick and install that on the 70 Satellite.
Glad everything seems to have worked out.
Posted By: barracuda7199
Re: Brake pedal "meh" thinking about braided lines. - 03/21/14 04:07 AM
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A new aluminum 1 1/32 master cylinder with adapter from doctor diff fixed your same problem on my car. Stops far better than it ever has and has the best pedal it ever had. His masters are going on all our cars from here on out.
Nailed it earlier! Glad you got it straightened out. I will say again that The good doctor diff has the best deal on the new lightweight masters with adapter.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/21/14 11:38 PM
Road test was very successful! Was a riot banging through the gears and then heaving on the brakes watching the twins plastered against the seatbacks.
Would not mind a little more aggressive pad or a master with more pressure, might look into one of the Dr.Diff units!
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 12:29 AM
So I have a question while we are still on the subject of brakes- If the St.Regis rotors and caliper adapters work on the A-body spindles does it follow the pads do as well?
Under A-body part numbers there isn't much for good pads but under St.Regis there is several police and taxi pad sets listed.
I was out road testing today and it felt like on the last application of the brakes it felt faded, I don't think the Wagner premium semi-metallic pads I have on there are going to cut it.
Posted By: Twostick
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:06 AM
I'm not up on what caliper is what but if the A-body one is the same as the R-body then the R-body cop pads etc should work. If the calipers are different but you are using R-body adapters I would think you could then use R-body calipers instead and whatever R-body pad you wanted.
Kevin
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:21 AM
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I'm not up on what caliper is what but if the A-body one is the same as the R-body then the R-body cop pads etc should work. If the calipers are different but you are using R-body adapters I would think you could then use R-body calipers instead and whatever R-body pad you wanted.
Kevin
The R body and A body Calipers will interchange, some cars got 2.75" piston calipers and others got 2.60" calipers.
I'm thinking the pads should interchange.
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:27 AM
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The R body and A body Calipers will interchange, some cars got 2.75" piston calipers and others got 2.60" calipers.
73-75 A calipers are 2.60" & 76 A calipers are 2.75" & they (73-75 and 76) A calipers interchange (with each other) & take the same pads.
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:36 AM
..what was the size of your new master cylinder piston compared to the size of the piston in the one that gave you problems?
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:37 AM
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The R body and A body Calipers will interchange, some cars got 2.75" piston calipers and others got 2.60" calipers.
73-75 A calipers are 2.60" & 76 A calipers are 2.75" & they (73-75 and 76) A calipers interchange (with each other) & take the same pads.
Now that I have a taste of good braking on the car I want more of it.
I think some calipers and pads might be on order soon.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:41 AM
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..what was the size of your new master cylinder piston compared to the size of the piston in the one that gave you problems?
The one that is in there now is a truck unit around 1.10" there was a .960 unit before.
Posted By: RapidRobert
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:47 AM
I used 2.75" calipers with ceramic pads & they were adequate around town & I never needed to challenge em so I dont know how they'd be under performance conditions. The R calipers are all 2.75" & the bleeder location would likely be different on em & not sure how they interchange & reportedly (by Andy) Andy's bible covers that subject very well. If I wanted more I'd get some 11&3/4" horseshoe adapters/ 11&3/4" rotors. They take the same calipers & I'd do a bed in procedure with some performance pads
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:50 AM
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If I wanted more I'd get some 11&3/4" horseshoe adapters/ 11&3/4" rotors. They take the same calipers & I'd do a bed in procedure with some performance pads
Already have the big rotors, to be honest I did not know Mopar had two different piston sizes on the slider type caliper or I would have opted for the larger ones right off the bat.
Not money wasted as I still have to do the swap on the Dart, just hate wasted time.
I was hard on the brakes today, they felt faded out when I got home. I was flogging them pretty hard in a 5 minute window. Upgrades!
Posted By: can.al
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 01:54 AM
you have increased .140" (more than 1/8")
i think 1/16" is about 12% increase in volume...and leg, and will
explain the hard pedal with a lot less travel.
Posted By: skicker
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 03:58 AM
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I was hard on the brakes today, they felt faded out when I got home. I was flogging them pretty hard in a 5 minute window. Upgrades!
Sounds like you have it to where a more aggressive pad is all you need.
The typical parts store pads all tend to fade somewhat once heated up.
If you get to a higher grade of pad (harder)the stopping is better once heated but sometimes suffers when not being driven aggressively.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 10:58 AM
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Sounds like you have it to where a more aggressive pad is all you need.
Which is why I was looking at the Police/Taxi listings for St.Regis.
Most parts books don't show an interchange, but that might not be an issue. Wasn't sure if there was a slight change in the caliper and the calipers are only 20 bucks a pop.
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The typical parts store pads all tend to fade somewhat once heated up.
Had very good luck with the Wagner Thermoquiet in the past with the turbo cars, we would flog them for dear life. But they might have a different formulation or just the weight difference in vehicles is enough to push them over the edge.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/24/14 11:02 AM
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you have increased .140" (more than 1/8")
i think 1/16" is about 12% increase in volume...and leg, and will
explain the hard pedal with a lot less travel.
I'm considering a swap of masters, I'll do pads and calipers first. I'll need another master for the Dart, so what I order will depend on how the car is with different pads and calipers.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 03/29/14 01:05 PM
Bigger calipers will be here today and the pads have already arrived.
Pads are Wagner SX84/SX7017 severe duty pads.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 04/04/14 02:59 AM
Just an update- Swapped the calipers and pads over last night and bled the system out. Drove the car for about 1/2 hour and worked on bedding the pads in. As expected there is more pedal drop than before due to the larger pistons (2.75" vs 2.60") but the brakes seem to work better. I'm going to drive the car this weekend for a few hours and see where everything settles out. I think the current master is going to stay as with the current caliper and pad setup the pedal drop to pressure ratio if you will seems good to me.
Next step is to move to the rears and get them where they belong with 11 x 2.5" brakes again. Already have two brands of shoes on the way along with new wheel cylinders from e-berg.
Thanks to everyone who chimed in! The car is much more fun to drive with some proper brakes and not diving about.
Posted By: gdonovan
Re: Brake pedal "meh" thinking about braided lines. - 04/04/14 10:11 PM
Rock Auto strikes again!
I ordered the first set of heavy duty pads and they came in correct so I went ahead and ordered a second set to have on the shelf.... and they are generic junk pads in a generic Big A Automotive box.
sigh.
