braking woes

[72blue]

Good day and Happy Easter to all,

I am just about ready to put a .270 hole through this pickup...so angry. Anyway, I have 72 short 4x4 that is getting close to being done (BEEN THAT WAY FOR A WHILE NOW) and cannot get any brake pedal at all. All lines are new; stainless and hose as well. This was a kit from GMC Paul's and it came from inline tube. I had to modify or make some lines to go exactly where I wanted, and I am a novices at flaring, but have zero leaks now. New calipers and wheel cyls. New booster, master, and combo valve; all came from Pauls as well, not sure of the manufacturer. They all look similar to factory, but the rear of the master has no pilot hole for the factory rod to go through from the booster side; it just has a small dimple machined into it and there is a small nipple that protrudes from the booster that makes contact with it. Very minimal clearance here and I believe this is what we are looking for. We bled the brakes with a pressure pot, and in went motor etc. and I never checked the pedal until I went to go for a test run yesterday, spongy pedal...air in the system right? Bled the old school way only to find no air escape. Tapped on the master, calipers etc no air escaping.
Read a pile of old posts and decided to bench bleed master. That done, reinstalled and also want to point out that I learned to push that little pin in on combo valve while bleeding. After all the above was gained, still no pedal. Continued old school bleeding and no pedal. Checked for leaks and found zero. What am I doing wrong? Been very calm just disappointed. Read more old posts and continued bleeding, no pedal just goes to floor fairly easy. Changed master to a different stock type (bench bled as well) and put a small bolt in to take up slop that would be present because as stated above this is similar to factory but no plunger protrudes into master. No difference in pedal.
What the hell? I am smoking out my ears. Been working in this for days, didn't call Pauls because I just thought there was air. There could still be, but I cannot expel it. Was just hoping someone could help out until I get in touch of who ever made the master, booster, combo valve on Monday. I am all out of ideas and am totally lost here.
Sorry for the huge long post, but just wanted to save someone from playing tag with me asking what I have and so on.
Amy help is welcomed and greatly appreciated.
James.

[spinning wheels]

the master has no pilot hole for the factory rod to go through from the booster side; it just has a small dimple machined into it and there is a small nipple that protrudes from the booster that makes contact with it. Very minimal clearance here and I believe this is what we are looking for.


Is there a small rubber washer like seal between the MC and the booster? I was missing that part, but I had a hard pedal. You write that you have a soft/spongy pedal. If you are not missing the rubber washer, I would think you have air trapped in some of the bends. The only other item I can think of, is that the rod attaching to your brake pedal needs adjusting. In other words, your pedal isn't pushing the rod far enough. Hope this help, I know brakes can be a PIA. Good luck.

[john02fxdl]

Are you getting any fluid out of the bleeders at all? I had a similar problem with brand new parts and I didn't have a pedal at all and nothing coming out of the bleeders, no air, no fluid. So I resolved the issue by using a vacuum brake bleeder. Tool guys sell these and I think craftsman does too. Easiest thing I ever done and the result was a very firm pedal.

[72blue]

Is there a small rubber washer like seal between the MC and the booster? I was missing that part, but I had a hard pedal. You write that you have a soft/spongy pedal. If you are not missing the rubber washer, I would think you have air trapped in some of the bends. The only other item I can think of, is that the rod attaching to your brake pedal needs adjusting. In other words, your pedal isn't pushing the rod far enough. Hope this help, I know brakes can be a PIA. Good luck.[/QUOTE]

There is a seal around the shaft that comes out of the booster.

I am getting fluid out of the bleeders, sometimes it shoots out like a raped ape with no air or spitting like occurrence, and other times it dribbles out like an old man trying to take a leak with a severe prostate problem.

Hope this helps.

[CTENTA1]

Hey James,

Have you checked ur vacuum going to booster? Well, im no brakes expert but what i can tell you is from past experience and it might help. I had the same problem on a car owned. Due to lack of Vacuum going to my brake booster. Looking at ur pics i can see you have a beefy built engine. Im ture you know that when you start moving into bigger cams you start loosing vacuum to ur brake booster. Im not ture what exactly you have done to your engine but i can tell you my small block had a 280 cam and this was what caused my problem. The brakes would bearly grab until it built vacuum. It was really soft but the pedal would just go more than half ways down before it even grabbed. Now im not saying this is ur problem but check that out if you havent already. If this is the case they sale this deal that you can buy that feeds vacuum to ur brake booster. Hope this helps you out.
Good luck!

[72blue]

Ctenta1 long time no see or talk. It was killing me when you answered so I went out and checked, don't think the neighbors liked it (no mufflers yet), but there is 15 lbs or in lbs or whatever. The cam is an isky 505t grind with 505 lift and I seem to remember 280 or so duration.I have been doing all this bleeding with the engine off though hmmm.... I wonder if I should have the engine running. Now all that could be wrong is a set of bad masters, or a bad booster, or a bad combo valve, or a connection that is pinched , or a leak somewhere I cannot find yet, or...man this is killing me. So many thousands of $ sitting out there practically finished and no whoa. If someone with a grand came by when I was at the peak of my frustration I would have said get it out of my sight before I come to my senses and change my mind. Well I still have her for now and I know I would have regretted it.
But really, I am by no means an expert at anything automotive, I just know enough to be dangerous, however I have bled braking systems before never with this problem. I do know that when it is all finished it will all be worth it. Can someone confirm to bleed with engine running? Man that will be a wild job leaning over the wheels with the open pipes growling back at me. Mm mighty loud. I can just make believe I am at the drags listening to the cackle contest.
If no progress is made by Monday, I will probably load it up and take to Coast Clutch and Brake to seek some professional assistance.
Thanks guys very much; oh and whatever the problem is, count on me to post it up because if I had a $ for every thread that I followed in the search that had the exact same symptoms as I that just stopped feeding info right when they fixed the problem I would be rich, well maybe be able to go out to dinner anyway.
James

[ERASER5]

Did you add power brakes? And is your MC a Disc/Drum(big bowl/little bowl) or a Disc/Disc(big bowl/big bowl) with Disc/Drum proportioning valve?

When I did my disc conversion, I had NO pedal at all. now I have been doing brakes for 20 years and I had never had that happen. After scratching my head, I tool my new MC apart and found a big pile of rubber/junk/stuff in the bore. I cleaned it out and put the MC back together, re-bled everything. Now I had a good squirt on the fronts, but not on the back. So, I did the unthinkable. I swapped the front lines to the back and bled the back. Re-set the lines correctly and bled the fronts. Much better, but not perfect. Hmm.. I had forgot to install the 10lb. residual valve! Did the whole mess over again and finally I have excellent brakes.

Hope this helps.

[Longhorn Man]

is there a chance that the drum brakes are out of adjustment?
Is the brake light on the dash lit up?

[72blue]

Ereaser, the bore on the mc is 1.25" and the front bowl is larger. It already had power brakes on it, but I have been getting pretty good I did switch cabs only, not all the guts inside. The kit I have had instructions and said that "some trucks will require the hole in the firewall to be extended up .250 inch." When I installed the mc and booster, it took me some time to find my original clevis or whatever its called to connect to the pedal. When I did, I had to remove the booster and ream that hole out in the fw to fit ( don't know if it matters but the donor cab is a 71 2wd no power discs up front.) It squirts out of the front and the back, just some pedal pushes are better than others. Don't know why though??
Longhorn Man, the light I cannot get to come on at all and that is adding to the fire, but I guess I have been pretty fortunate to be able the continue this project when others are selling theirs.
What is that little pin for in the front of the combo valve? Pressure equalization while bleeding? I tried putting a test light with key on from bat pos to combo valve term and cannot get the light to light up either. Help!!!!
James

[72blue]

Had to laugh... looked at my signature below all my posts and about fell out of the chair. I must not have been taking care of this truck cause it is not taking care of me. lol
On a serious note, I did leave out some info...the rear end is a 9.5 ring gear 14 bolt out of a 1989 light duty 3/4 ton with semi float 6 lugs. Does this need a super high amount of pressure to actuate the cylinders? We took off one drum and put pedal down and saw only one side of wheel cyl moving (keep in mind that there is no pedal at all). I used .250 tubing all the way to the rear, then 3/16 going from the hose off the frame to the wheel cyls if that is enough description.
James

[soba_03]

OK with 1.25 bore master cylinder and 1/4" lines I would say that you don't have a big enough master cylinder bore. You said that you have some bleeders squirting really well and others that are just a trickle. If my thinking is correct I would bet that rears were the ones that didn't squirt very well. I don't believe that you need to have the truck running if your using a vacuum bleeder, if your doing it manualy I would say start the truck.. My .02

[americanmusc1e]

Originally Posted by 72blue

Had to laugh... looked at my signature below all my posts and about fell out of the chair. I must not have been taking care of this truck cause it is not taking care of me. lol
On a serious note, I did leave out some info...the rear end is a 9.5 ring gear 14 bolt out of a 1989 light duty 3/4 ton with semi float 6 lugs. Does this need a super high amount of pressure to actuate the cylinders? We took off one drum and put pedal down and saw only one side of wheel cyl moving (keep in mind that there is no pedal at all). I used .250 tubing all the way to the rear, then 3/16 going from the hose off the frame to the wheel cyls if that is enough description.
James

One side of the cyinder moving is probably normal.

like someone else said, IF YOUR DRUMS AREN'T ADJUSTED TIGHT YOU WILL HAVE A SPONGEY BRAKE PEDAL.

I'd listen for a leaking brake line, if thats not it, it could be air, although if it's air your prop valve would probably be stuck (brake light on)

other than that you could have a bad master cyl.

also check for a leaking caliper or wheel cylinder

the way i bleed brake is by forcing fluid up from the bleeders to the master cyl. starting with the longest line and working to the shortest (jack the front of your truck up until the master cyl. is level)

hope this helps

[72blue]

Soba_03, correct the rears are trickling.
Americanmuscle, thanks for the knowledge...I had all day to cool off and will give all my lines a once over to see. My drums were NOT adjusted properly at the beginning a few days back and the first thought was that this would fix my problem...it didn't. Then the fight was on.
On another note, the brake warning light is ON, and now I cannot get it to come off. It came on when I put a c clamp on it in an attempt to hold it in (don't have that lil cllip thingy). Now it won't come off.??? Guess I don't have enough pressure to force it to center.
Gonna go try cussing at it more to see if that helps.

[soba_03]

Heres all I was trying to say, and I could ery well be wrong. Here is my thoughts. If you went from stock line which I believe is 3/16th and not it's 1/4 you have more volume that you have to try and move with the same size master cylinder that worked with the 3/16 lines. You may not be getting the pressure that you need to the rear brakes. I believe that your valve on your master (prop valve) if your truck is drums all the way around it acts more like a distribution block, if it's a disc/drum brake truck then it's a proportioning valve, it will reduce pressure going to the front brake calipers, because you don't need all the pressure and the brakes are much more efficent.

If your light is on and it's a newer Prop/distribution block then you may need to reset it. It's a shuttle valve and could very well have set during a bleeding secession. I believe that at one time there was something on here that talked about it. However CPP tech will help. I would look at that first.

I hope this all made sence.

Good luck...

[72blue]

Soba_o3, I just went out and checked the old lines and the rears had 1/4 inch line to the rears and the orig 12 bolt rear end had 3/16 from there, just like what I have now.
I think I am gonna try taking out the booster and mc out of a 70 truck we have and start over since I know it is working.
Thanks for all replys.
James

[4x4Poet]

Shot in the dark:

Did you attach a vinyl hose to each bleeder as you bled the brakes to verify that no more air remained in each line?
Did you close off each bleeder before your helper let up on the pedal?
Did you work the bleeders, or a helper?

If you have the time & patience, explain how you bench bleed the master cyl.

[dznucks]

Not to highjack the thread. But could someone elaborate on resetting a proportioning block to get the brake light to go off.

I installed a ECE front dics kit 10 years ago and the light is still on. I am also about to insall new brake booster and master cylinder as well as rear discs, so i am curious to what the problem is with 72blue's truck.
Good luck

[72blue]

Dznucks, to reset the valve, just do a panic stop type push down on the pedal. they say this will do er. another way is to find out which side is getting the pressure and open one of those bleeders for ex. the front and bleed a bit out but not too long or that will direct the valve the other way. If I am wrong someone will let u know.
4x4poet, I removed the mc from truck, filled w fluid about half inch from top, screwed plastic adapter from bench mc bleed kit, attached hose to adapter, ran hose to mc and submerged in fluid with that clip thingy for front and rear ports, pushed n on mc w large Phillips SD, waited a bit(10 sec) and repeated. Watch air come out of tubes. After a few pumps, waited a min or so and repeated. The directions that came with the new mc #2 said to all this until I could not move mc very much like a quarter in.??? That never happened, took like 20 pumps, but I could still push in on it all the way...was super hard but I could do it. I am not super man, nor am I strong; my dad looks like a nfl lineman don't know what happened to me. whatever...did I do this incorrect?
And to answer your q about putting a tube on the bleeder no I did not. would make sense to do so now, but i never have b4.
And when helper pushed on pedal, I performed all bleeding...had good system I think. said down they pushed THEN I open...more like crack a quarter turn...close, THEN said up and repeat as needed.
now if there is a major issue with any of this let me know. I am lookin for leaks to, but for some reason I am lookin for some huge gusher that could be heard leaking bc that is the only thing could cause this in my opinion, but cannot even find a small leak.????
Help Lord Help ME.
James

[MickMc]

1. Clamp off the rear brake line (where the line comes off of the frame to the rear axle)
Now do you have a better pedal?

2. Screw bolts into the master cylinder. Take out the brake lines and insert bolts. The threads are SAE. Do the front lines and try the pedal, do the rear lines and try the pedal.
Now do you have a better pedal?

This will tell you if the master cylinder is working or not (holding pressure)

If you now have pedal the next item to check is the porportioning valve.
The valve will shift to a port that has pressure, is the brake light on? Have you pushed the button on the valve?

Keep us posted.

Mick

[69GMCLonghorn]

Hey James,

I have a 1 ton GMC with all kinds of brake problems, leaking axle seals, etc. I've done my brakes about 1000 times. What have I learned through all of this? There's a time when even the guy with the award for being the brokest a** in the forum has to break down and take it to a shop. Have someone else look at it. Maybe it's some small pi**-ant little thing that you're not seeing. Call AAA, tow it in, and sit at home and have a 12 pack for lunch while some other poor SOB figures out what the heck is wrong with it.

Best of luck to ya!

[americanmusc1e]

Originally Posted by 72blue

Soba_03, correct the rears are trickling.
Americanmuscle, thanks for the knowledge...I had all day to cool off and will give all my lines a once over to see. My drums were NOT adjusted properly at the beginning a few days back and the first thought was that this would fix my problem...it didn't. Then the fight was on.
On another note, the brake warning light is ON, and now I cannot get it to come off. It came on when I put a c clamp on it in an attempt to hold it in (don't have that lil cllip thingy). Now it won't come off.??? Guess I don't have enough pressure to force it to center.
Gonna go try cussing at it more to see if that helps.

From what you said I'm about 95% sure you have air in your system, it sounds exactly like what I went through in February when I changed out to front discs
if you don't believe me read my disc swap thread near the end http://67-72chevytrucks.com/vboard/s....php?p=3171895

If you don't have enough fluid coming out of the bleeders (prop valve stuck) its almost impossible to bleed it the old fashioned way. you will have to find a way to get the air out of the lines in order to reset the proportioning valve, the only way I've found to do this is to force fluid up from the bleeders to the master cylinder(starting with the longest line and making sure the master cylinder is level)

I would bet money that you have air in your system from the info you've given me

good luck

[72blue]

Americanmusc1e, ur right, I have an air brake system. LOL
69GMCLonghorn, that is exactly what I did, well I loaded it on the car trailer in 4 low.
I took it to a local brake shop, Whitakers, in Santa Maria. Jim the owner has done quite a bit of work for me in the past; all my alignments, and told me to bring it in. One call to McGaughys (they made the bracket, booster, and master) left me kind of POed, they said "sounds like there is air in the system." Well no ****. How about some trouble shooting help or somethin??? They had no intention of making suggestions. Oh well, whatever then. Back to my brake shop help. The pickup hadn't been at the shop 10 minutes when Jim called me back and found the problem. You'll never guess. Well, maybe u could have if I had posted some pics, but I had my calipers on backwards, that is left on right and vise versa. What a dip **** I felt like. Jim then reversed the calipers to have the bleeder on the top reset the combo valve, and bled the system and perfecto, pedal feels just like it did 3 years ago when the pickup was last on the road. I was so happy man. Thanks to all of u who have helped. Air, a brake systems worst enemy. Now it is at Central Coast Spring where they are gonna weld the rear axle perches in place because the rear came out of an 89 light 3/4 ton. It is a 9.5 ring gear semi float, so I still have my 6 lugs. If all goes well, I will have it home tomorrow and be bolting on all the small stuff (grill, lamps, bumpers etc.) and be cruisin in the Pismo car show cruise. I would like to get some electric uncorkers before I have my exhaust done though.
Well, good bye for now and thanks again.
James

[4x4Poet]

Bleeding procedures sound good though I've pinched the master cyl bleeder hoses closed before letting up on the manual cycling of the master. Just to keep air from reversing back into the master.

Still, most GM-style masters bench bleed pretty easy even without pinching off the bleed hoses.

As to that idea to put bolts in the master cyl outlets, don't you still have an extra master to try that with? So you can check your technique without any disassembly?

[MickMc]

Originally Posted by 4x4Poet

Bleeding procedures sound good though I've pinched the master cyl bleeder hoses closed before letting up on the manual cycling of the master. Just to keep air from reversing back into the master.

Still, most GM-style masters bench bleed pretty easy even without pinching off the bleed hoses.

As to that idea to put bolts in the master cyl outlets, don't you still have an extra master to try that with? So you can check your technique without any disassembly?

The idea is that if you block off the ports with a bolt, and now you have a good firm brake pedal, then master cylinder is not at fault. This is an easy way to check a master cylinder before taking it off an running to the store and purchasing a new master cylinder. If the master cylinder is at fault they usually bleed back internally, that is that is the sinking pedal you get when you're parked at the stop light and slowly the pedal is falling away.


If you block off the rear lines near the rear wheels and the you have a good brake pedal, then the rear brakes are the issue, usually they need to be adjusted.

Mick

[Tom Vogel]

...bleeder holes have got to be on top. Air only goes up. The only other way is to flip your truck upside down.
Not laughing at you though, this has happened to Lots of people.