Need Brake helP!!! New info. see last post from me

[KBUCK1]

I have installed all new braking system. Original 76 disc brake setup in front with drums in the rear. It's a manual brake system with ram charger master cylinder. Also, i have h block installed instead of proportioning valve.Brakes have been bled what seems like a hundred times. No air is coming out. Master cylinder was bench bled 6 or 7 times at this point. Plugged master cylinder ports and pedal does not move. So, Im good there. Here's the problem.the pedal goes down about half way and is very spongy. Rear drums are adjusted where they are dragging on drum. I jacked the truck up and had my wife mash the pedal as far as she could and I could still turn he tires in the front and the back. When bleeding the brakes the pedal will go to the floor but with the bleeders closed it only goes half way but still no brakes. Calipers are installed with bleeders in the highest position. Any suggestions on what the problem might be?

 

[pcf_mark]

Did you "bench bleed" the master cylinder? You may have air stuck up top and can't push it down. You can get a kick at a local parts store that you can use.

 

[KBUCK1]

Did you "bench bleed" the master cylinder? You may have air stuck up top and can't push it down. You can get a kick at a local parts store that you can use.

Yes.i have bench bled it 6 or 7 times. Literally . Also, plugged the ports to verify it was bled and the pedal is rock solid indicating there is no air in the master

 

[PaveBronco]

I wonder if your Ram Charger MS piston bore isnt big enough to push enough fluid, or there is something going on with that H block.

 

[Apogee]

What year Dodge Ramcharger master cylinder are you using? Or better yet, what bore size? The 1979-1993 MC had a 1.125" bore MC, so if that's the unit, you definitely shouldn't be having an volume issues. I run the factory 1" bore MC on my '77 with disc/drum (2-7/8" front caliper pistons and 15/16" wheel cylinders) with vacuum assist without any issues and the 1-1/8" bore unit pushes ~25% more volume than that.

 

[KBUCK1]

Master cylinder for 85 ramcharger

 

[KBUCK1]

Ok, took the drums off the back and had my wife press the brake pedal. wheel cylinder pins never moved. so, either the pins are wrong or the wheel cylinders are wrong. I havent driven this truck in twelve years. Its been torn down that long and we are just now getting around to building it back. I have another bronco and wondering did I install the wrong cylinder pins. I cant locate any other ones. They are the bullet style and not the "t" style. Is there a "wrong" wheel cylinder pin? I have 11 inch drums from a 76. Or did they sell me the wrong wheel cylinder?

 

[DirtDonk]

Not so sure it's just something with the rear cylinders, if you could turn the front wheels with the brake pedal mashed.
Certainly doesn't mean that nothing is wrong back there. Just that if it is, it's not your only issue.

Out of curiosity, why did you go with a non-stock master, vs a stock EB manual brake version?
Is your Bronco a '76, or did you just use brakes from a '76?

It sounds like your master is working from all the tests you've done, but was anything else changed? What about the pedal rod? Did you modify your existing one, or replace it with something else?
Even though it does not sound like a rod issue, did you verify that your new master has the deep piston, so the rod can stay retained safely? If so, did you measure your new rod so that your pedal is where it should be?

Is there a chance that your front calipers are not sliding on their mounts and keeping the piston too far away from the rotor?

Good luck. Sounds like one of those strange ones that will keep you scratching your head for awhile. Until you find out it's something simple.
Hopefully...

Paul

 

[DJs74]

Is this a brake conversion or just component replace? If you did the disc conversion on the front, like DirtDonk said, make sure you have clearance between the steering knuckle and the caliper. I as well as many others I'm sure had to grind a fair amount of steering knuckle material away to get the proper clearance. Also - make sure the clearance is sufficient for sliding movement of the caliper / not just enough clearance to get the caliper bolts through. Could be a combination of mechanical issues and air in the lines??

Also - and this might sound elementary but make sure your bleeding procedure is by wheel distance from the MC. For example: right rear first, left rear second, right front third and finally left front. this is just basically due to the amount of fluid/air per line & distance and you'll want to start with the longest distance and work your way towards the shortest.

DJs74

 

[KBUCK1]

Not so sure it's just something with the rear cylinders, if you could turn the front wheels with the brake pedal mashed.
Certainly doesn't mean that nothing is wrong back there. Just that if it is, it's not your only issue.

Out of curiosity, why did you go with a non-stock master, vs a stock EB manual brake version?
Is your Bronco a '76, or did you just use brakes from a '76?

It sounds like your master is working from all the tests you've done, but was anything else changed? What about the pedal rod? Did you modify your existing one, or replace it with something else?
Even though it does not sound like a rod issue, did you verify that your new master has the deep piston, so the rod can stay retained safely? If so, did you measure your new rod so that your pedal is where it should be?

Is there a chance that your front calipers are not sliding on their mounts and keeping the piston too far away from the rotor?

Good luck. Sounds like one of those strange ones that will keep you scratching your head for awhile. Until you find out it's something simple.
Hopefully...

Paul

I returned the master and got another new one. Front seems fine now. I just liked the looks of that style master cylinder better. Its not a conversion. Its the factory 76 dana front end and disc setup.

 

[DirtDonk]

A reasonable enough reason! I think others have used non-stock masters because they looked cooler or more "modern" or whatever, than the originals. Or they were just tired of the old and wanted something new.
As long as it works...

So just the front seems fine only? Still some issue with the rear?
If so, maybe the shoes are on backwards/reversed? Not tight enough? I know you said they were dragging, but by how much?
If you question how tight or if the wheel cylinders are right, try driving it with the parking brake applied only one notch at a time to see if the pedal gets firmer or the braking seems to function better.
Obviously you don't want to get the parking brake too tight, or you're just dragging the shoes needlessly. But as a short-term experiment to see the differences, it's a good tool.

You asked about getting the wrong wheel cylinder too. The good news is that the '76 and '77 EB's only used one style cylinder, so the odds of a parts guy getting you the right one the first time are much higher than earlier models. The bad news is that it's ALWAYS been possible to get the wrong part due to either a mistake in looking it up, a mistake in re-boxing, or whatever other scenario you can think up.
So it always pays to verify, verify, verify, when it comes to brake parts.

Since it fit up correctly though, it sounds like, you're probably ok in that department.

Hope it's all working out.

Paul

 

[KBUCK1]

A reasonable enough reason! I think others have used non-stock masters because they looked cooler or more "modern" or whatever, than the originals. Or they were just tired of the old and wanted something new.
As long as it works...

So just the front seems fine only? Still some issue with the rear?
If so, maybe the shoes are on backwards/reversed? Not tight enough? I know you said they were dragging, but by how much?
If you question how tight or if the wheel cylinders are right, try driving it with the parking brake applied only one notch at a time to see if the pedal gets firmer or the braking seems to function better.
Obviously you don't want to get the parking brake too tight, or you're just dragging the shoes needlessly. But as a short-term experiment to see the differences, it's a good tool.

You asked about getting the wrong wheel cylinder too. The good news is that the '76 and '77 EB's only used one style cylinder, so the odds of a parts guy getting you the right one the first time are much higher than earlier models. The bad news is that it's ALWAYS been possible to get the wrong part due to either a mistake in looking it up, a mistake in re-boxing, or whatever other scenario you can think up.
So it always pays to verify, verify, verify, when it comes to brake parts.

Since it fit up correctly though, it sounds like, you're probably ok in that department.

Hope it's all working out.

Paul

Is it possible for the wrong wheel cylinder to bolt up? Could the pins that go in the wheel cylinder be too short? I can push the pin into the wheel cylinder and there is a gap between pin and the brake itself. Shouldn't this be tight already so any movement of the cylinder pins would move the brakes? When I checked it yesterday the pins were "out" against the brake. When the brake pedal was pressed nothinng happened. Im assuming because the cylinder pin is not going deep enough into the wheel cylinder. Does any one know how long the pin should be?

 

[DirtDonk]

Yes, they should touch at all times, with at least some resistance pressure to you pushing them in.
I would think that it's certainly possible to get the wrong wheel cylinder to bolt up. There are way too many variations there to be sure. There are plenty that would never fit, whether for register size or pipe fitting size, but many that would.
But I don't think they would automatically cause that issue. It also sounds like air in the line still.

I'm assuming that, since they've been bled to death (so to speak ;D) that you would have noticed whether or not the bleeder screws were facing up? Might check anyway, because it's easy to get a right on the left and vice versa.

The pins would be incorrect only if they were the wrong length or did not fit properly in the cup. But that would be easy to verify I think. If they look reasonably like they're seating correctly and the pistons are not over-extending when the brake is applied, I would think they're correctly matched. The pistons going that far back into the cylinder is an issue though.
Either no residual pressure check valve is present, or there's still air in the lines. And the residual valve only resists to 10 psi or so, so it's not that you can't push the rods back in with one present. It's only that it resists normal gravity backflow.

I'm still saying air in the line at the moment.
But have someone watch the master reservoir when you're pushing the pistons back in to see if much fluid is coming back in.

Paul