Vette Master Cylinder

Installed it yesterday. When bleeding the master and the brakes it seems like when the rears are bled the pedal drops to the floor but the fronts don't cause it to drop. Plenty of fluid coming out the front bleed screws, just the pedal doesn't drop as dramatically as the backs. Doesn't seem right. Test drive shows the rears will lock up but not the fronts. Even with the weight difference I'd expect the front tires to lock up too. The plan is to jack the truck up and check to see if the front drums are grabbing and continue bleeding the front. Anybody have any thoughts?

Is the master drum / drum ********** disk / disk? If it is drum / disk it will push more fluid to the front or rear. I ran all new bake lines and a vet master and no problems. Make sure that the shoes are adjusted right. That will cause one set to catch before the other.

I have the same thing going on except I seem to get more fluid out of the rear bleeders when the pedal is pushed. The rear resevoir is connected to the front brakes. When it's on jack stands the fronts do lock up but when I come in from a drive the front drums are cool. I'm hoping do more adjusting this weekend.

This is the point in your project where all kind of unexpected problems could be the "one thing" keeping you from being done. I don't know the history of your truck, so I am just going to list out all the things I can think of that could be causing the rear to get pressure but not the fronts.

As written above. Is it a disc/disc master cylinder? Find out for sure.

The line to the front brakes should be screwed into the firewall side of the mc

is the mc piston returning all the way back when you let go of the pedal? If not, no new fluid is going to get into the front brake circuit.

do your brake lights still work? The brake signal switch is now connected to just the front brake pressure. If they are not lighting up, then you are getting no pressure out of the mc to the front brakes system.

If your brake lights are working, yet you are getting no fluid to the front wheels. Then you might have clogged up brake hoses. They are made out of rubber and are made to flex. Chances are they need replacement anyway since they are pretty close to 40 years old now. I would recommend you pull the wheel cylinder end off and see if any fluid flows.

(A good way not to get fluid all over the place while messing with brakes is to get a glass jar. A Mason jar is just about perfect. Put a little bit of clean brake fluid in the bottom. Either stick a brake line into the fluid or connect a hose to reach under the fluid. Then you can sit in the cab, push the pedal while looking under the truck and watch either fluid or air bubbles flowing into the jar. Connecting a vacuum line from the bleeder screw to the bottom of the jar is a great way to bleed brakes by yourself. Just push slowly while watching for bubbles. When the bubbles stop and you still get fluid moving, close the bleeder screw and move onto the next wheel.)

If fluid is flowing fine through the hoses. Then you are looking at gunked up wheel cylinders.

If no fluid is coming through the hose, then pull the other end of the hose off and see if you have fluid at the end of the metal line. IF you do, then you have a bad hose. If you don't, then you have to trace the lines back to the MC and find the restriction.







I hope this made sense. Like I wrote at the top, I don't know your truck so I just threw in everything I could think of without giving you a brake operation lecture.

Get the littel speedbleeders from the HELP! section of the parts store, too. They work great, along with the previously mentioned hose/mason jar thing. Just make sure the wife knows she'll be missing 4 mason jars PERMANENTLY!

I also found that I had to open a bleeder on both the front AND rear circuits to move fluid.

Quote:

---

Originally Posted by XJ Chief

Installed it yesterday. When bleeding the master and the brakes it seems like when the rears are bled the pedal drops to the floor but the fronts don't cause it to drop. Plenty of fluid coming out the front bleed screws, just the pedal doesn't drop as dramatically as the backs. Doesn't seem right. Test drive shows the rears will lock up but not the fronts. Even with the weight difference I'd expect the front tires to lock up too. The plan is to jack the truck up and check to see if the front drums are grabbing and continue bleeding the front. Anybody have any thoughts?

---

I can't believe this. I am having the same problem as I type. I installed all new wheel cylinders (Ford van), new Vette master drum/drum, new brake rubber hoses front and back as well. I even went back with the stock pushrod and now the piston is against the snap ring. The rear line on the m/c goes to the fronts and the front lines goes to the rear brakes. I plugged the block with a plug where the rears used to come out of as well.

When I bleed the rear brakes, the fluid squirts out in a stream and the pedal goes to the floor. When I do the fronts, it comes out but dribbles out...and the pedal does not go to the floor, which is odd.

I had my old man step on the brake pedal and I couldn't turn the rear drums with it on the lift. I tried to turn the front drums, and they still can be turned.

I think what I may do is take the front drums off and bleed it with them off. I want to see it allowing the brake shoes to move more with the drum off will allow me to bleed the cylinders better.

I can't believe someone else is having the same problem as me right now...

I'll post back today or tonight as I keep on scratching my head! LOL

Well I just got back in. My brake lights are not working....I guess I don't have enough pressure. I even took off the front drums and had my dad depress the pedal. They didn't even budge.
I am wondering if the idiots who rebuild these things gave me a disc/drum master cylinder for a Corvette. Trust me, my wife's uncle is Joe Cardone, who owns Cardone auto parts rebuilding. His stuff is crap and they just opened a plant in Mexico. You think Mexicans can tell the difference between master cylinders? They just throw them in boxes and paint them!
Speaking of that, is there ANY way to tell the difference between the drum brake and disc/drum brake master cylinders? Before I take it off and exchange it, I'd like to see if anyone knows a way to just look at it and tell...

All great replies. I'm wondering if the master is the wrong type. Seems strange to have the EXACT same problem as a person who did the same swap at the same time.

Just got off the phone with Autzone. I questioned him as far as my master cylinder possibly being a power brake master cylinder being rebuilt and put in a manual master cylinder box. He tells me "about 1 in every 5 or 6 are just wrong or have issues/problems." That doesn't surprise me at all since my buddy who is ASE certified REFUSES to install any Cardone auto parts since they always fail or come back and he has to eat the labor. I love breaking my wife's uncles chops about the crap he "rebuilds..."

The number is definitely the 1371, and I even had the guy try a 69 Corvette, 71 Corvette and 76 Corvette....all the same...just double checking since they only list "power brakes" or "manual brakes" - no mention on their computer about drums or discs.

All Corvettes from 1964 on were 4 wheel disc brakes so at least that won't be the issue. Biggest difference between disc or drum usage is the check valves in the outlet ports, drum should have them, disc shouldn't. I use a 1970 Impala 4 wheel drum master cylinder on mine, same bore size as original M715 and should have the check valves for drum brakes.

Not for anything....none of those NAPA adaptors worked for me...now I am wondering if the Vette master cylinder is even the right application...
I am picking up a new vette master tomorrow morning around 11am...hopefully,it will work or else I may go with WetCJ used...a 4 wheel drum application for a 70 IMpala.
I should have just stuck with the stock master cylinder...like the old saying "if it ain't broke, don't fix it!" This master cylinder swap is a total pain in my you know what between all the wrong brass fittings and now this!

You know...if the corvette master is for 4 wheel discs, why would anyone recommend using it on a truck with 4 wheel drums? Maybe this is the problem...since others are having the same problem as me. I doubt all of us have a bad master cylinder! And considering all of the other information that was listed here as far as adaptors, etc., was incorrect, I am thinking that getting the drum brake master cylinder may be the answer. Seems that peope who are running the vette master are having problems with it or don't have much front braking capability like the one guy whose front drums are cold and his rears are warm after driving the truck....

I'm going to do a little more bleeding when I get time on Monday. Tonight I checked and my brake lights come on when I press the pedal down. Also, I hear the front drums working now that I didn't before. Could be that there's some air still trapped in the lines.

OK, lets discuss a few things:

First off, the part numbers probably came from me. I did my swap in Feb 2005. I bought everything from NAPA and made a tech post about it at the time. I left 1 part number off the list because my NAPA didn't have it. (One of the small adaptors) 4 different members bought the same parts and installed them on their trucks with no troubles. All 4 of them PM'ed me the missing part number. They all sent me the same one. I added them to my tech sticky. That sticky died with the Post nuke Zone.

I have not seen a picture of a "Corvette" master cylinder that looks like mine in months.

That is my "don't blame me" speech.

Why the Corvette mc? A former member,Tom Lawlor aka Spicergear, spent the time to look over all the brake mc catalogs all the auto parts stores he could find had. He was looking for a mc built to be used with the same design at all 4 wheels. Then he wanted the biggest diameter bore that was made for the same design at all 4 corners. The 1976 Corvette non power master cylinder was the winner. The 1976 Corvette was the last year Chevy offered it without power brakes. They had to make it so it would stop just as good as the power braked cars, just more effort. Therefore, it had a bigger diameter piston. Tom mounted one to his truck and it worked great. He told the Zone about it. I was probably about the 30th zoner to do the Corvette mc swap. I talked two of my female students through the swap in about 45 minutes. No problems were encountered except since they had never worked on brakes before, fluid was rubbed on my paint to get it off their hands.

Why disc/disc? This is were it gets complicated. Check valves, residual pressure valves, proportioning valves, etc... Brakes can be complicated. A disc brake requires very little movement of the piston to apply the brakes. A drum brake requires more movement. Depending on how your brakes are adjusted, it could be a lot of movement before the brakes actually do anything useful. We have it easy. We have the same style of brakes at each corner and they are all the same size parts involved. Therefore, we don't need a proportioning valve to determine how much fluid to not send to either the front or back. Residual pressure valves keep just a little bit of pressure in the lines so the shoes/pads don't have to travel as far to make contact. A check valve does the same basic thing just a little bit differently.

A principle of hyrdaulics is that only fluid in motion does any work. So, if you have 3 corners out of adjustment and 1 just right. Here is what happens. You push the pedal and it travels a little, but you don't really slow down. You pump it real fast and the pedal is a little higher and you are stopping more. You do another fast pump and you are stopping better still. The fluid stopped moving when you got pressure at the one good corner, the other three were just doing nothing. Your first pump pushed the other 3 out a little more, but not all the way. Your third pump got all 4 to finally working together and the pedal real high. A residual pressure/check valve would keep those other 3 closer to the drums and eliminate the 2 extra pumps for the most part. But, your one adjusted corner would probably be dragging and wear down to be equal to the other 3.

My mc is a true disc/disc and has no valves in the system. I can feel brake shoe wear with my foot because of pedal travel. I adjusted them just right before the Texas FE. I dragged Pistolnuts M715 500 miles behind mine on a trailer. I had a pedal about 1 inch lower by the time I got home. One pump and it was super high. When I adjusted it, 3 clicks on each brake brought it back up. I towed a M35 40 miles and gained another inch of travel on that trip. 14000 pounds flat towed with no extra brakes will do that. 2 clicks brought it back up. I didn't measure the shoes, but they look the same. So, the wear is miniscule but very evident to the amount of fluid needed to move them that much further. I like it this way because I KNOW the state of my brakes any time I push the pedal. I also like manual transmissions, tail dragger aircraft and exposed hammer guns so I might just be "convenient challenged."

Would a drum/drum mc work? You bet it would. Joe has one and it works great. But, it has a smaller cylinder bore than the Corvette one. If you are not going to add a booster, you will have to push the pedal harder to stop.

This is one of those situations where you can go 4 different paths to get the same result. If you bought a true disc/disc or drum/drum mc. It should be sending equal pressure to all 4 corners. Why aren't you. The mc is made for a disc/drum set up, you didn't bench bleed the mc and still have air in one of the circuits, you have a leak or loose fitting somewhere(air molecules are smaller than liquid molecules. Air could be sucked in without fluid leaking out.), the piston isn't getting a full stroke for some reason.

I didn't mean this to turn into a lecture on brakes or a justification for the Corvette mc. Lots of guys Luckypabst and Dave are two I can name who installed FSJ mc's and love them.

I would suggest for the problems mentioned in this thread that you guys start over. Bleed the mc at the mc and just go fitting by fitting to each wheel cylinder. If you don't get good pressure from both resevoirs at the mc, look at your pedal linkage and if it is good. Take the mc back to the parts store and demand a real disc/disc-drum/drum mc.

"But, it has a smaller cylinder bore than the Corvette one. If you are not going to add a booster, you will have to push the pedal harder to stop"

Hey Tim, wouldn't that be just the opposite? Won't the smaller bore master cylinder create a higher pressure than the larger bore with the same leg pressure applied? A little more travel will be required of course but isn't that why on a vehicle with both styles of brakes offered (manual and power) the manual system will have the smaller bore? Pressure=Force/Area
(double checked this in my Wagner manual, didn't think I knew that formula did ya? LOL Todd)

Quote:

---

Originally Posted by Barrman

OK, lets discuss a few things:

First off, the part numbers probably came from me. I did my swap in Feb 2005. I bought everything from NAPA and made a tech post about it at the time. I left 1 part number off the list because my NAPA didn't have it. (One of the small adaptors) 4 different members bought the same parts and installed them on their trucks with no troubles. All 4 of them PM'ed me the missing part number. They all sent me the same one. I added them to my tech sticky. That sticky died with the Post nuke Zone.

I have not seen a picture of a "Corvette" master cylinder that looks like mine in months.

That is my "don't blame me" speech.

---

AHA! So this is all YOUR fault. :p

I think I'll get it worked out. Rest of the swap went so smoothly I knew something had to go wrong. Appreciate your explanation of the selection of the Vette master- great to know information. Thanks!

All I can say is that I bench bled the m/c correctly and there are no leaks at all. I really think that what I may have is a m/c that was set up for disc/drum. I don't think it is defective, but rather a wrong one.
If all else fails this afternoon with the new one, I will return that and go with another m/c. I hope all goes well with it but my luck sometimes runs bad.
Think about it...it seems to me that the disc/disc corvette m/c would be a pretty limited piece to be able to get, especially considering it is 30 years old and is only found on the corvette. I can go to any three auto parts stores locally and get one off the shelf. Seems a bit odd to me that these are so plentiful. I really wonder if there could be that many disc/disc manual m/c's floating around or they just rebuild any GM ones and throw 'em in boxes?

By the way Barrman, I am not blaming anyone here....I am not mad in the least...and I don't think I even got the numbers from you. I am just questioning everything at this point because nothing yet has worked for me, beginning with the fittings and ending with the m/c....and my truck is still on the lift after almost two weeks (inclulding down time for new shoes from Memphis...:(

Joe, you are right about the pedal effort. My bigger bore pushes more fluid for the same travel as you, but I have to push harder. I was thinking about how to write the proportioning valve stuff and just typing the top part on automatic and screwed up. Thanks for catching it.

I think you are right about the availability of the Corvette mc. I had to wait 3 days to get mine. I ordered it from a small NAPA that you always had to wait 3 days to get anything though.

Barrman,

Quote:

---

That sticky died with the Post nuke Zone.

---

Not dead --- just lying low for a while in my cache. Jon has this and the other stickys.

I think this is the sticky you are talking about.

http://landru.myhome.net/sivart/MasterCylinder.htm

Update.....new master (101371- not a Cardone) on and still the same...trickling out the front bleeders and the front brakes dont even work. I then remove the two lines coming off the brass brake block and have my dad hit the pedal. Just about trickles out. I remove the pressure switch and line coming off the m/c to the top. Have my dad hit the brake, nothing comes out. The block is clean with no restrictions.
I then remove the brake line from the master and blow through that - perfect. Now I am down to the adaptor that screws into the m/c. That is fine. I unscrew that and then put the plastic bleeder adaptor that comes with the master with hose back into the m/c. I hold the plastic hose above the resivoir with the m/c lid off. I have my dad press the brake and some fluid comes out, but doesn't seem as much as it should be coming out. I then put the hose into the fluid and have my dad release the pedal. The pedal rod (stock) had a little play so the piston is coming against the snap ring.

Now what???? Can it be I have another disc/drum setup? I doubt it. Something is wrong here....

Well fellas, I've just about had it with this vette master cylinder. Luckily, I kept my rebuilt Wagner single resevoir and am about ready to bench bleed it, reconnect my rear brakes to the block, and reconnect the 1/4" line from the m/c to brake block.
Just for kicks, I put some brake fluid in the single one off my truck and pushed in the piston...brake fluid shot 2 feet out the side hole. If no one sheds some more light on this problem, by next weekend I will have the old one back on and return that P.O.S. vette cylinder to Autozone. I am at the end of my rope...
Not for anything, I don't understand this...I've worked on new ABS braking systems and can't figure this simple brake problem out. Funny thing is that I've even discussed this with my ASE master tech friend and once he heard I was swapping master cyliders from other vehicles etc. he was like "why don't you just stick with what works for sure...you're asking for nothing but trouble modifying braking systems...no matter how simple it sounds..."

Something isn't right with your dual circuit mc is my thought.

Quote:

---

Originally Posted by Barrman

Something isn't right with your dual circuit mc is my thought.

---

This is the second 101371 master cylinder I have used....the first one was a Cardone and this one was remanned in Canada...I forget the brand.

What specifically do you think may be wrong Barrman? I am the furthest from a novice and have exhausted my thoughts and ideas. I am open to anymore ideas or suggestions. I even tried bleeding two lines on one side. No matter what I did, when I bled the fronts, it trickled out and the pedal never went to the floor as others have experienced the same problems as I.

I have a feeling/inkling that the others who are experiencing the same problems as I don't have much of front brakes and may think that an adjustment is all they need...which is not the case. I would venture to say that these people are using 90% rear brakes and if they are lucky, the fronts are barely making conatct with the front drums.

If the pedal isn't hitting the floor when you crack a bleeder, you have a problem and it sure isn't air trapped in the line. Even my dad who has played with cars all his life (he's 72) doesn't understand it. Neither does my buddy who is ASE master and he's been wreching for almost 20 years.

Thsi doesnt really surprise me since if it weren't for bad luck, I wouldn't have any luck at all...

If some of you want to try a drum/drum cylinder then I will offer this up as one I would try. 1970(last year for all drum) Chevy c-30 1 ton truck. They had HBA (humungus big azzed) drums all the way around. Another choice might be mid 70's 1 ton J truck as they used drums thru '73 I think. I'm still with SupaMod though, too many 'zoners have done the vette swap for it not to work.

I've done it twice using same parts. No problems and both front and rear brakes work fine. I did replace the original brake hoses with new hoses and flushed the lines. Both times I bled the MC on the truck.

To be honest, I am so disgusted I am probably going to go back to stock - at this point I can't be going to the parts store and keep ordering master cylinders and trying them, possibly returning them etc. just because they aren't working.
Someone recommended a 1970 Impala drum/drum master and above a C30 one ton drum/drum master. I sincerely believe that the two I have tried were drum/disc master cylinders. I cant prove it but how can two do the same thing?
Well I can't work on anything until next weekend, so I have plenty of time to think as to what I may try next. So far, the stock m/c has my vote since I know it will work.

You should be getting equal pressure out of both mc circuits. Does yours look like this?

http://img401.imageshack.us/img401/6...vettemczo1.jpg

This is mine installed on my truck. If yours is different, then I go back to the parts store gave you the wrong one. Lots of different mc's will bolt up to a specific vehicle. But, normally only one is the right part.

Barrman...both m/c's looked exactly like yours...then again, many Chevy masters look like that one from the 1970's...
My setup looks exactly like yours - from the master cylinder to the adaptors to the lines coming off the m/c!
Help!! LOL

I am as stumped as you are. I feel bad that we couldn't talk you through this one. I just don't know what to tell you to do.

Exactly...I am stumped as well....imagine the frustration I have been experiencing!

Okay, I've checked just about everything there is to check now. Wheel cylinders are good, lines are good. Only thing left IS the master. Here's what I'm thinking...

I think the push rod needs to be lenthened. I think the front cylinder is being compressed and getting great pressure to the front (rear wheels) piston but the push rod is stopped before it can push the rear (front wheels) piston. Lengthening the push rod would allow the front and back to both be pressurized.

http://www.tegger.com/hondafaq/maste...-schematic.gif

This is a simple system, there really isn't anything else left to trouble shoot so this week I'll adjust the pushrod and see if that's it. Other than that, there's nothing left to do except go back to the original system or keep trying other master cylinders until I find one that works.

Sure sounds like 3 of us are having the same thing. I did some more adjusting this weekend. Pedal feels better and truck seems to stop better. I looked in the adjustment slots and turned until all had about 1/4" of threads showing. Also had my son pump and cracked the front bleeders again. More than a trickle like I had before but it's not shooting out. I also pulled the LR wheel and drum because I saw a drop of fluid down the backing plate. I think it was coming from where the line attaches to the wheel cylinder so I put another crank on it. Unfortunately I only get a few hours a week to fiddle with my truck.

Not sure I'm following your thinking here, the front piston is supposed to be moved by the pressure created in front of the back piston (the area shown in your brackets) not a mechanical connection. Yes the mechanical connection is there but should only come into play if there is a pressure loss in the rear. Usually you can feel when this is occuring, does it feel like the pedal goes part way then you feel the contact with the front piston? Or am I missing your point?
I've fought some brake systems in the past so I can understand your frustration. That said let me offer some thoughts I've had in reading these posts the last couple days-
Brake adjustment can make a big difference in how smoothly the bleeding process goes. If you have any doubts adjust the brakes out all the way tight while bleeding to eliminate that possibility. Back off later.
I was originally taught to bleed a new master cylinder by plugging both outlets with my finger tips while someone else slowly stepped on the pedal. Hold them tightly closed so no air can get back in when the pedal is released. When you have fluid pushing past your finger for the complete stroke, hook that line back up. Messy yes, but you know for sure that you are creating pressure. Might be worth a try.
One other thought, if your lines happen to be same size, switch them on the master cylinder just to see if your problem switches ends also. If yes, master cylinder issue.
Just my thoughts, Good Luck, Todd

Lengthening the pushrod won't do a thing. I lengthened mine and about a half inch and at that point it was pushing the piston into the bore. Forget lengthening it unless you plan on doing some serious fabricating and moving the entire brake pedal assembly back a little to compensate for the longer pushrod.
I went back to a stock pushrod because lengthening it would create more problems.
It won't be too long before I go back to the stock m/c either.
As far as bleeding the fronts to get the pedal to go to the floor - I couldn't get it to happen. Couldn't get a stream if I tried and I tried everything! I even cracked both bleeders on one side and tried that. I even tried to experiment and removed the stinking drums to just see if "an adjustment" problem was occuring - by allowing the drums on all fours to expand without restriction, an din theory allowing the piston to "travel" more and push out m ore fluid.

Nope....adjusting your drums in my humble opinion and almost 20 years of working on cars has nothing to do with how successful bleeding your brakes will be.

I've bled tons of wheel cylinders and the pedal always goes to the floor or drops when cracking the bleeders. I couldn't get the pedal to drop no matter what I tried. Something is wrong...

Success! At least for now. I pressure bled the system from the brake line out of the master and after pushing a whole lot of brake fluid through the system I coaxed out all the air. I then reconnected the line and reverse pressure bled the system from the furthest point and the brakes are now working. What a PITA this has been. If I still have brakes and no fluid leaks next time I drive I will be satisfied that it is %100 done.

You have more willpower than me. I returned the vette master about three hours ago, got my money back and will be installing the Wagner single resevior m/c Thursday or Friday evening.
I don't own a pressure bleeder...how were you able to pressure bleed each line separately off the master cylinder? Is there some sort of adaptor?
When I bled those brakes, I had my old man pump them manually so much, that night he could barely walk! I've never had to use a pressure bleeder so far with anything...well I am glad you found success.
Just for kicks, can you do me a small favor? Now that everything is working, have someone get in your truck and pump up the brakes and you go and crack a front bleeder. Let me know if the pedal drops to the floor and you get a steady stream of fluid...that will be a good test!

Since installing m/c and wheel clyinders I'm on my 4th bottle of brake fluid. When it was up on jack stands the front wheels do lock up. I haven't pulled a front drum to see if there's been any shoe wear but after my last drive all 4 drums felt slightly warm. I'll have to ride the brakes a little more next time but am thinking maybe I'm getting closer.

I was wondering if this trouble has anything to do with the different size lines? Wouldn't the same volume of fluid have less pressure in a larger line? Or would the lines from the distribution block out to the fronts equalize that? At the m/c the one to the fronts is 1/4 and 3/16 to the back if i recall. I don't know if the m/c ports are the same size but I know the threads are different.

Just a comment on brake bleeding procedures. Pumping the brake is not the proper way to bleed them,(according to my tech school instructer,many years ago).The "proper way" is ,open bleeder,push down pedal,close bleeder,release pedal ,repeat,repeat,etc. My son was working on his friends truc and couldnt get brakes by pumping and opening bleeder,told him to try my way,said it wouldn't work. Well after about 30 seqeunces of the proper way ,they had brakes. Dad-one ,Junior-0. Supposedly pumping can cause too many bubbles in the fluid.

Quote:

---

Originally Posted by Fastfrankie

You have more willpower than me. I returned the vette master about three hours ago, got my money back and will be installing the Wagner single resevior m/c Thursday or Friday evening.
I don't own a pressure bleeder...how were you able to pressure bleed each line separately off the master cylinder? Is there some sort of adaptor?
When I bled those brakes, I had my old man pump them manually so much, that night he could barely walk! I've never had to use a pressure bleeder so far with anything...well I am glad you found success.
Just for kicks, can you do me a small favor? Now that everything is working, have someone get in your truck and pump up the brakes and you go and crack a front bleeder. Let me know if the pedal drops to the floor and you get a steady stream of fluid...that will be a good test!

---

I'll give it a shot next time I pull the truck out. As for the pressure bleeder, just make one. I used a pump sprayer and some 1/4 ID line. Not that fancy and only cost 20 something dollars. I was going to make a super cool one but I didn't feel like tracking down a master cylinder cover and drilling a hole in it. Mine is really just the pump spayer and the 1/4 ID line. It fit nicely over the 1/4 OD brake line. That's the reason I had to reverse bleed it after clearing the line, when I reattached it to the master I'm sure a little air got back in while I reconnected it.

Here's a link to where I got the idea:
http://www.bmw-m.net/TechProc/bleeder.htm

This might explain why the (pump, push-hold, open-bleeder, close-bleeder, pump again) method is not working.

Year's back, I had a similar problem with the brakes on my Amphicar. I simply could not get all of the air out of the system using the normal pump hold method. I went thru many jugs of fluid and many hours if frustration.

Finally got it purged of air by putting a container with fluid at each wheel with a hose from each bleeder -- did the slow pump and release keeping the master cylinder full. The brakes have been fine now for years.

Here is what was going on!!

With pressure applied to the pedal and a bleeder opened it would go to the floor as expected. After closing the bleeder and then releasing the pedal the piston in the master cylinder would return to the normal at-rest position supposedly refilling with fluid. However that was not happening. The rear cup on the master cylinder piston was drawing outside air on each quick long return stroke introducing more air each time. Maybe if I had released the pedal more slowly it would have filled with fluid and not air but I don't really know because I solved the problem as mentioned above.

This could very likely explain the reason for some of the problems mentioned in this thread since the front brakes are plumbed to the rear cavity on the dual cylinder. The rear piston, where push the rod is, has a cup exposed to atmosphere. However this doesn't explain why in one case above where the pedal did not go to the floor. I don't get that one.

The normal (pump, push-hold, open-bleeder, close-bleeder, pump again) method might work if the brake pedal is release very very slowly after closing a bleeder.