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Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594507 03/18/14 09:48 AM 03/18/14 09:48 AM
Joined: Jan 2003 Posts: 21,067 Niles , Ohio T therocks oh wait.but hey.lets see.oh yeah.
therocks oh wait.but hey.lets see.oh yeah. T Joined: Jan 2003 Posts: 21,067 Niles , Ohio	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 Chrysler Firepower

Re: Brake pedal "meh" thinking about braided lines. [Re: therocks] #1594508 03/18/14 09:52 AM 03/18/14 09:52 AM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	Quote: 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. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594509 03/18/14 11:01 AM 03/18/14 11:01 AM
Joined: Feb 2009 Posts: 1,274 Ontario.Canada C can.al pro stock
can.al pro stock C Joined: Feb 2009 Posts: 1,274 Ontario.Canada	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

Re: Brake pedal "meh" thinking about braided lines. [Re: can.al] #1594510 03/18/14 11:31 AM 03/18/14 11:31 AM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	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. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594511 03/18/14 12:56 PM 03/18/14 12:56 PM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: 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. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: Brake pedal "meh" thinking about braided lines. [Re: Supercuda] #1594512 03/18/14 01:16 PM 03/18/14 01:16 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	Quote: 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. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594513 03/18/14 01:18 PM 03/18/14 01:18 PM
Joined: Jan 2003 Posts: 8,016 Polson, MT DoctorDiff master
DoctorDiff master Joined: Jan 2003 Posts: 8,016 Polson, MT	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. Contact info

Re: Brake pedal "meh" thinking about braided lines. [Re: DoctorDiff] #1594514 03/18/14 01:33 PM 03/18/14 01:33 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	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. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594515 03/18/14 02:09 PM 03/18/14 02:09 PM
Joined: Jan 2003 Posts: 32,928 Grand Prairie,Texas stumpy I Win
stumpy I Win Joined: Jan 2003 Posts: 32,928 Grand Prairie,Texas	Seems like your hung up on installing braided lines. Just do it and then you can go about fixing the original problem.

Re: Brake pedal "meh" thinking about braided lines. [Re: stumpy] #1594516 03/18/14 02:17 PM 03/18/14 02:17 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	Quote: 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. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594517 03/18/14 02:24 PM 03/18/14 02:24 PM
Joined: Apr 2011 Posts: 280 GEORGIA barracuda7199 enthusiast
barracuda7199 enthusiast Joined: Apr 2011 Posts: 280 GEORGIA	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.

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594518 03/18/14 04:15 PM 03/18/14 04:15 PM
Joined: Jan 2003 Posts: 31,016 Oregon A AndyF I Win
AndyF I Win A Joined: Jan 2003 Posts: 31,016 Oregon	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.

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594519 03/18/14 05:24 PM 03/18/14 05:24 PM
Joined: Jan 2003 Posts: 15,338 Omaha Ne T TJP I Live Here
TJP I Live Here T Joined: Jan 2003 Posts: 15,338 Omaha Ne	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. www.tandmautomotive-omaha.com

Re: Brake pedal "meh" thinking about braided lines. [Re: TJP] #1594520 03/18/14 05:41 PM 03/18/14 05:41 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	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. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594521 03/18/14 06:51 PM 03/18/14 06:51 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	Pulled the pads off and it looks like they had uneven contact with the rotor, will head out to take a pic. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594522 03/18/14 07:03 PM 03/18/14 07:03 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	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. 8079342-DSCN7585d.jpg (71 downloads) "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594523 03/18/14 07:28 PM 03/18/14 07:28 PM
Joined: May 2003 Posts: 6,561 Downtown Roebuck Ont Twostick Still wishing...
Twostick Still wishing... Joined: May 2003 Posts: 6,561 Downtown Roebuck Ont	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

Re: Brake pedal "meh" thinking about braided lines. [Re: Twostick] #1594524 03/18/14 08:07 PM 03/18/14 08:07 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	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? "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594525 03/18/14 09:00 PM 03/18/14 09:00 PM
Joined: Jun 2008 Posts: 10,847 Oakdale CT gdonovan OP I Live Here
gdonovan OP I Live Here Joined: Jun 2008 Posts: 10,847 Oakdale CT	In for the night, I can't get a good seal on the banjo fittings. Try again tomorrow.. "I think its got a hemi"

Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594526 03/18/14 10:20 PM 03/18/14 10:20 PM
Joined: Feb 2009 Posts: 1,274 Ontario.Canada C can.al pro stock
can.al pro stock C Joined: Feb 2009 Posts: 1,274 Ontario.Canada	no check or residual valves for discs... Last edited by can.al; 03/18/14 10:21 PM.

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