Brake line plumbing withOUT a combo valve?

[Kern Dog]

I have had a ongoing problem with the brakes in the Charger. I have tried several master cylinders, combination valves and the brakes still suck.
Here are the stats: 1970 Charger. Front has 12" Cordoba rotors, 2.60" piston calipers spec'd for a 73-75 A body, Raybestos pads. Rear is 10.7" rotors with 1.5" piston calipers (Dr Diff kit). I am currently using an aluminum 15/16" non power master cylinder, also from Dr Diff. Below the master is a drum/drum combo valve.
From 2001 until February of this year, I had a power booster on the car, along with an iron master cylinder spec'd for a 73-76 disc/drum A body. The brakes were great EXCEPT at low speeds, due to the lumpy cam and low vacuum. I switched to manual to have predictable braking.
I have tried 3 different master cylinders, and this 15/16" one has the best feel so far, but the brakes are still pathetic. Yesterday I drove my brother-in-laws Duster and was blown away by how fantastic that car braked. Its all factory stuff on that car, but from different years. 11" rotors, 2.75" piston calipers from an '88 5th Avenue and 10" drums. NON power stock master cylinder spec'd for a 73-76 A body. The larger front calipers got me thinking....I bought a pair of Raybestos 2.75 calipers and started swapping them in. What if the newer, larger calipers and brake pads make no difference? Where do i go from there?
The Charger feels as follows: You press the pedal and while there is resistance, it just feels like the brakes are not responding very much. Its just like when brakes are fading: Increasingly firmer pedal but little reaction. Today was the first time I got the tires to skid, and I had to really STAND on the pedal to get it. The rears skidded, but the car didn't feel like it was slowing down any faster the moment before they skidded like you'd expect. THIS is where the point of this post comes in!
What if the combination valve is a POS? Has anyone plumbed their brakes without one? My thoughts are to run a line from the M/C front reservior to a TEE, splitting off to each front wheel, THEN run a line from the M/C rear reservior, through an adjustable proportion valve, then to the rear of the car. I read in Mopar Action about this, April 2004. Has anyone else made this change? Does anyone have advice on the matter? Thanks, Greg

 

[YY1]

IMO, nearly doubling the surface that pressure can be applied to on the caliper should have a noticeable effect. Are you using a "Texas" shaped valve? I understand these are all the same and were still used on trucks well into the 90s. I see them in salvage yards all the time. I paid $5 for the last one I picked up. Your m/c is for a non power disk car?

 

[67 coronet]

if you dont currently have some kind of prop valve then that is your problem.if the car was all drum,it will only have a diverter valve.your back brakes are comming in too early,that is why they are locking up first.put in an adjustable prop valve after the diverter block,in the rear line and try some testing with differnt settings.(i normally start with max close and adjust up from there)

 

[5.7 hemi]

Drum/drum combo valve is wrong for a 4wheel disc setup. I would use an adjustable proportiong valve from wilwood, and then dial in the brakes, it works really good.

 

[Kern Dog]

Thanks guys. I think that there is something else in play here that isn't making sense.
EVERY manual master cylinder that I have tried has delivered similar results: firm pedal and minimal reaction. The biggest M/C I used was a 1 3/16" unit..Heck, I didn't know! It was new and free from a buddy. The pedal was super firm! I couldn't skid on dirt though! I tried a 1 1/16" iron unit. It was a little bit better. The 15/16" unit in there now FEELS okay, but that feel doesn't directly translate to enough pressure at the calipers. I wish that I had a brake pressure guage. Some guys have said that 1000 PSI is a minimum to have.
Call it apples and oranges, but I feel driven to improve the brakes in this car because my BILs Duster works so well! To quote a song from the 60s....Theres something happening here... what it is aint exactly clear...

 

[Kern Dog]

if you dont currently have some kind of prop valve then that is your problem.

I HAD a disc/drum prop valve in there before installing the drum/drum valve. There was no difference. It performed exactly the same.
For me, the primary issue is that the firm pedal gives terrible action to the wheels. If the car stopped great but locked the rear tires, THEN I'd understand the need to focus on the bias. Maybe its a matter of the FRONT calipers not getting enough volume/pressure?
I really DO appreciate all opinions though. Please keep them coming!

 

[Kern Dog]

Screw it. The power stuff is back on the car.
I usually don't give up on car stuff, but I'm just tired of fighting with it all. I have 3 of those 'Texas" disc/drum prop valves. I took one of them apart and cleaned out the gunk.
I should have it all back together tomorrow and I'll report back.
Thanks for the help.

 

[tpodwdog]

HERES AN IDEA................. put on the car what BELONGS on the car and you WONT have all these problems!!!!

you back yard engineers FRANKENSTEIN these cars together with parts that have no business being on it ,,,,,and wonder why its not working....or why its giving you grief...i gotta chuckle....amusing!

heres a famous quote : " theres never enough time or money to do it right the first time....but theres ALWAYS time and money to do it 2wice " ...why is that????

 

[Kern Dog]

R E A L L Y? You are going to take that route? What are you, a dinosaur? Yeah... GREAT idea! Lets step backwards and convert our cars BACK to 10 inch manual drum brakes! I asked for help, not a lecture of the good old days. Do you still listen to the AM radio? Are you running 14 inch bias ply tires as well?
Get real, man. A properly set up 4 wheel disc system will easily outstop a drum system, especially in repeated stops. Sure, if I was only into diaper polishing my car and sitting in lawn chairs at car shows, YOUR suggestions would be fine. I DRIVE my car. Hills, corners, straight lines, everything.

 

[Kern Dog]

The car is all back together and all is well. It stops better now than it did before I began. The power booster and master cylinder are from a 75 Dart. The proportioning valve too. These were the same parts that I started with, so I was confident that the car would be at least as good as before. The only change was adding the larger front calipers.
I finally have "brake dive" again! Maybe down the road when I get more free time, I'll try using this master cylinder on another car to see if the symptoms are the same. I spent $ 85 on the M/C, about $20 on fluid, $35 on brake lines and who knows how much in cussing and frustration!
Thanks to those who tried to help, Greg

 

[tpodwdog]

...YES...REALLY....remind me to never get in your car,,,which i will aptly name...FRANKEN-PIG.

getting into a battle of wits with an unarmed man just aint my dillio . youve already proven yourself "undesireable" by your actions. i have a few parts from a 71 Monte Carlo...and some from a old Hudson....would you like these parts to put on that car too???

 

[5.7 hemi]

So you put back the stuff you started with, and now it works good? I feel ya, I went thru alot head scratchin' and "new words" before I finally got mine to work. So what is on there now? Just asking cause it might help someone down the road who does a conversion of sort.

 

[Kern Dog]

Well, lets be careful to not annoy tpodwdog, because I guess we shouldn't ever deviate from stock!

The Charger started out as a 4 wheel drum brake car. In 2002 I added a master cylinder and power booster from a 75 Dart, along with the front 11" disc brakes. I also swapped in the disc/drum prop valve. (Okay with that, tpodwdog? Rick Ehenberg from Mopar Action thinks so)
In 2003 I upgraded to the 12" rotors from a 77 Cordoba. In 2005 I added a rear disc brake kit from Dr Diff. (OHhhhhhh No!!! a NON stock part!) The kit was featured in a Mopar Action magazine article, along with other kits from Master Power and Scarebird.
Last month I felt that the low idle vacuum produced by my '509 cammed 440/493 was inadequate because low speed braking wasn't that good. I asked on Moparts under the screen name 'Frankenduster" about what options there were for manual brake master cylinders. I got several replies and things made sense. After trying a new Master power 1 3/16" unit, it was deemed to be too stiff with too little brake force. I tried a known good factory disc/drum M/C with a bore size of 1 1/16". It was a little better, but still not good enough. I contacted Dr Diff and explained the situation to him. I have the utmost respect for the man. Ask 100 of his customers and I'll hazzard a guess that 99 would do business with him again. Cass Eslick told me that a 15/16" master would deliver a softer pedal with a longer stroke. It did exactly that, except that the calipers didn't get whhat the M/C was doing. There was something spooky going on that I wasn't able to determine. In some small way, isuspect a problem may have been in the 2 different combination/proportioning valves that I used. When I put the power stuff back on, I took a known good used prop valve apart and cleaned it before the install.
What mechanic HASN'T had a situation that defied logic? Who hasn't gone "off of the reservation" and had some trouble?
Innovation and progress never comes from people that stick with what they already know. It is those with the curiousity and a pioneer spirit that blaze a trail for the rest of us. I took a shot. What shot did YOU take, TPODWDOG?

 

[Kern Dog]

HERES AN IDEA................. put on the car what belongs on the car....

You mean like a big white P L Y M O U T H on the side of a car that is NOT a Superbird?

 

[tpodwdog]

i dont really feel the NEED to explain myself to an immature vagrant like yourself.....and im not going to ....i will tell you this..

that purple car that youre ripping apart is completely stock
it starts...stops... everything on it works THEY WAY ITS SUPPOSED TO... i have absolutely no qualms about jumping in that car and driving from pittsburgh to california....AND BACK !

the big white PLYMOUTH decals have NOTHING to do with its performance WHAT-SO-EVER.

if thats all the better you can come up with to make an EFFORTLESS attempt to intimidate me,,,,you need to do way better than that. ,,,,SLICK !

the best information anyone on here can give you...I GAVE TO YOU ALREADY.... so bashing a completely ORIGINAL antique vehicle....THAT FUNCTIONS PERFECTLY is all that you can come up with...then you need to go to the TPODWDOG SCHOOL OF PISSING PEOPLE OFF.

like i said before....i wont get into a battle with an unarmed man...and from what i can see just through your texts,,,,you certainly are unarmed...juvenile....immature......and just an all around troglodyte!

i just called the print shop...and im having 2 big white "FRANKEN-PIG" decals made for you so you can put them on YOUR quarter panels....so send me your address so i can get them to you as soon as humanly possible !

best of luck to you with FRANKEN-PIG....someday i hope to actually meet you if you dont kill yourself in it first !

 

[5.7 hemi]

Well I'm knowledgeable enough about brakes to offer up any advise. I did use a wilwood 1 inch mc, 11 inch front disc conversion, stock 10x2 1/2 rear drums, braided stainless flex lines, wilwood adjustable proportioning valve and 8 inch booster with an adjustable brake pedal rod and after alot of messing around they finall work good. Have you looked on other sites to see what others have done?

 

[67 coronet]

i didnt understand that you had converted to 4 wheel disc earlyer in the post.if you are running a factory prop valve(frnt disc/rear drum)your brake bias is not correct.i still think if,in the future,you try anything else i would recomend a diverter valve and an adjustable prop valve too the rear brake line.then,adjust from there.

 

[5.7 hemi]

I meant to say "not knowledgeable enough", brain was moving faster than my fingers, my bad.

 

[Kern Dog]

i dont really feel the NEED to explain myself to an immature vagrant like yourself.....and im not going to ...

the big white PLYMOUTH decals have NOTHING to do with its performance WHAT-SO-EVER.
.... so bashing a completely ORIGINAL antique vehicle..

best of luck to you with FRANKEN-PIG....someday i hope to actually meet you if you dont kill yourself in it first !

Wow... Pretty impressive.
The huge decals are not stock. They may have been DEALER installed, but it negates the assertion that this is an original car.
4 wheel drums? GREAT! I'm happy for you that your car is reliable enough to cross the country. Thats what they are meant for. I am surely younger than you in mind and spirit. I am also open minded enough to allow some flexibility in my thinking. I often default to the elders and give respect until they prove otherwise. YOU fired the first shot by tossing out derogotory references to FRANKENstein creations. My car will out run any stock B body in every category other than fuel economy. That includes 1/4 mile, top end, cornering and braking. It squeaks less, has fewer rattles, rides better and is far more fun to drive. The problem that I had with this brake conversion is a mystery at this time, but I may one day figure it out. OPEN minded people don't just take everything at face value. We dig deeper.
Didn't YOU ever question authority, or did you simply do as you were told? Did YOU ever wonder WHY things were the way that they were, or did you just accept them? A car show with nothing but stock restorations would bore me to no end.
I feel sadness for those without a creative spirit. I'm not a hippie by a long shot, but I can understand some of their ways. At least THEY are happy. YOU need a pill or something.

 

[tpodwdog]

immature....need i say more?...youre young AND IT SHOWS!