OK another brake question

[DirtDonk]

So just for another data point.
When the engine is off and you push on the pedal, is it solid, rock hard, and basically doesn’t move?
Then, when you turn the key with your foot still on the pedal, it goes to the floor immediately?
That’s what it sounds like, but I wanted to be sure.

Whether that’s the case or not, but especially if it is, I would recheck your booster rod to master cylinder piston distance.
This is the most common issue, as you have probably read here over the years, when adding new parts. And that’s true whether you add one new part to an old one, or both are new.

Short of getting that tool, just pull the master forward as the hoses/lines will allow, adjust the booster rod out, a quarter inch for example, then gently push the master back up against it.
If you feel the master piston touch down on the rod before the mounting flanges meet, then you know where you stand as far as rod depth.
Note that distance.
Pull it back apart, adjust the rod inward that amount, and push it up again. If the two surfaces meet before the rod touches the piston, lock it down and check your pedal action again.

In the modern age, there is every reason to suspect that you could easily have gotten two bad master cylinders in a row.
If this is just the first new master cylinder, it’s very possible that it’s bad right out of the box.

 

[ngsd]

Thanks, I did buy the tool and will be checking that when I get back. I also got a reverse bleeding pump to see if I can push any air backwards.

 

[ntsqd]

What do you mean by "reverse bleeding pump"?

 

[DirtDonk]

Never used one, but I think that means they push fluid in through the caliper and the cylinders, back up to the master cylinder.
Is that correct?

 

[ngsd]

Yes apparently these wer designed more for the issue with not being able to get all of the air one way out and pushed back up and exits to the MC. Makes sense. https://www.braketools.com/max-pro-brake-bleeder.html

 

[ntsqd]

Yes apparently these wer designed more for the issue with not being able to get all of the air one way out and pushed back up and exits to the MC. Makes sense. https://www.braketools.com/max-pro-brake-bleeder.html

More or less how aircraft hydraulic brakes have been bled from the beginning. After Lars mentioned this to me a while back while I was having trouble getting the Bronc-up's brakes to bleed I used a left-over 1.5 qt. calibration gas bottle (a small disposable fire extinguisher could also work if it has a metal valve) to create a pressure bleeder with this specifically in mind. I used a low pressure regulator (0-15 psi that I *think* came from mcmaster) to pressurize the bottle and made a siphon tube for it so that it draws brake fluid from very near the bottom of the bottle. A small ball valve on the outlet lets me turn the flow on and off as needed w/o disconnecting the air. I've never needed more than 10 psi and usually operate at 5 psi or less.

You will want to seal the bleed nipple threads. Some leak more than others, but I've never encountered one that didn't leak at least a little. I have been using dielectric silicone grease VERY carefully applied to the threads (ONLY!) on the bleed screws to do this. I haven't really been doing this long enough to say for certain, but I'm of the opinion that using this grease in the bleed screw threads may also keep them from rusting up. Absolutely, positively can not use a petroleum based grease for this. The best choice would be to use brake system parts assembly lube in the bleed screw threads. My experience with trying teflon tape in the threads was that it didn't work.
It is worth noting that when I use my vacuum bleeder that I also use the dielectric grease to seal the bleed screw threads because air will leak past the threads there too and create false bubbles in the bleeding line.

It is helpful if the tubing used is clear so that you can see any bubbles that might be from running low on fluid in the bottle. I use some clear polyurethane from mcmaster with a rubber hose section on the end of it to connect to the bleed screws. There is a small hose clamp on the rubber tubing to clamp it down onto the bleed screw, and a "Clamp-tite" tool formed clamp holding the rubber hose onto the urethane tubing.

 

[ngsd]

I tried everything I could think of and then put the old booster and MC on it and it was fine. One thing I noticed is that the old reservoirs are bigger thatn the one I put on but still not quite sure of the issue.

 

[ksagis]

Did you ever compare MC bore?

 

[ngsd]

Did not measure but looked the same

 

[ksagis]

Copy, glad it’s fixed!

 

[ngsd]

Copy, glad it’s fixed!

Thanks, this one is going to give me gray hair. (too late). That issue is solved then it went from running perfectly upon fresh start up to a wild miss. I thoght maybe the new pertronix dist igniter was cooked with the wrong coil as it was back firing and sputtering. I changed the coil, put another distributor in it, another carb, check the timing over and over, checked all of the valves were opening as they should and still cant get it to run. This was kind of like the brake issue where I am scratching my head. I think it is cursed!

 

[Speedrdr]

***********This was kind of like the brake issue where I am scratching my head. I think it is cursed!********

You just stumbled upon yet another of Murphy’s Law.
Murphy’s Law of Systems states that any mechanical system upon reaching completed functional status will automatically cause a different component to malfunction for no apparent reason.

 

[ntsqd]

You can take a perfectly good part, put it on an airplane Bronco, and it will fail.

 

[ngsd]

OK I am back from fishing for a while and back at it. Changed Booster, MC (twice) checked calpier clearnace, bled a hundred times (ok maybe 10) and still just mush for brakes. What proportioning valve are you using for the drum/chevy disc?

 

[SLOWnEASY]

Reading through your posts you put the original booster and master cylinder on and the issue was fixed. Did you take the old stuff off again and put the suspect new back on?
If so I would suggest putting the old stuff back on and get it working again. Then swap one piece at a time and see which part causes the failure. If it was me I would work from the firewall out. After you have it working on old parts swap in the new booster and test.

 

[ngsd]

Reading through your posts you put the original booster and master cylinder on and the issue was fixed. Did you take the old stuff off again and put the suspect new back on?
If so I would suggest putting the old stuff back on and get it working again. Then swap one piece at a time and see which part causes the failure. If it was me I would work from the firewall out. After you have it working on old parts swap in the new booster and test.

Yes I should have updated it, I thought it was better but after a few minutes it was back to the same. I am changing out the prop valve today as the next guess.

 

[DirtDonk]

One thing I noticed is that the old reservoirs are bigger thatn the one I put on but still not quite sure of the issue.

I missed this part the last time. But what that tells me is that the new parts are completely different than the old.
Why is that? That’s something we need to find out. Because reservoir size is one of the few things that seems to have remained constant over the decades.

Regarding new parts, the fact that they are the same design does not make them exactly the same.
I’ve seen casting differences that could cause the calipers to interfere with the knuckles. So if you have not already, even though we don’t think this is the problem, you need to verify daylight between the caliper and the knuckle.
That’s an absolute necessity in all conversions. And at various times during their life cycle.

You said you ordered the tool, did you ever verify the piston rod clearance on the new coupled pair? Meaning the new master on the new booster.
Since your old ones work, I wouldn’t be changing the proportioning valve necessarily. I’d be looking at different masters and boosters.
Or at least what’s wrong with the existing ones.

Speaking of proportioning valves though, I was curious what type you had in it, and what type you were planning to order.
Is it an original Ford part, or an aftermarket part?

 

[ngsd]

I purchased the larger aluminun res from WH and no luck there either. I also tried two different size reservoir MCs just for giggles. Clearance is OK. Yes the tool worked great and was off originaly but still did not solve it. I have the usual brass aftermarket PV (toms) on there now. I cant remember if the old one was the same or not. I have another one here and also have a wilwood adjustable one that I can try.

 

[DirtDonk]

The adjustable type is only plumbed into the rear line. So it would have no effect on either the front, or the whole system. Unlike the standard combination valve.
So that would at least eliminate a combination valve as the problem.

Have we seen pictures of this whole installation yet?

Is there a more thorough way to test a booster?
It’s acting normal from a vacuum standpoint, but I wonder if there’s some disconnect internally.
Be nice if there was an easy way to remove it, mount the master cylinder up and see if you have brakes. That would isolate everything from the booster.
Since it sounds like you’ve replaced the Booster and master at the same time and it worked, then replaced booster master with the bad and it didn’t work, and then replaced at least one, if not multiple master cylinders with the same booster and it didn’t work, perhaps the booster is bad after all.

 

[ngsd]

I did try different combos of booster and MC's without luck. The PV is next so stay tuned!