500psi T-Bird Calipers

[ksagis]

@ksagis you can use whatever you want to make a connection, 37/45…as long as the other side is the same. It’s all what you choose. And a banjo is a banjo regardless of what’s attached to it.

I follow that aspect, yes. The aspect I was fuzzy on was getting to the 37 degrees. I’m betting they sell an adapter to go from the female in MC to -3 male AN. Will poke around some, thanks.

 

[chuzie]

While I couldn't find it when I went back, I thought you isolated one front side?? If so did you isolate both fronts independently?

You are correct. One of the initial readings I took was at the tee above the front differential. Removed the driver side hard line and measured pressure directly from the tee with the passenger side still attached. Reading was about 1500psi. I then removed the passenger side caliper and lines, plugged the port on the tee. Reading was 2500psi.

Seems like awhile back we had a thread where the rebuilt calipers had issues with the bleeder screws and pulling air back into the system?

I saw that thread and have experienced the same issue before with air getting past the bleeder threads. When I bleed, I close the bleeder before releasing the pedal to prevent air from being drawn back into the caliper. My jack handle comes in handy to hold the pedal down in this one man band.

What part of Washington are you in. I have a pressure bleeder you could borrow.

I abandoned ship almost 2 years ago when the anti-gun laws got out of control.

 

[gnpenning]

You are correct. One of the initial readings I took was at the tee above the front differential. Removed the driver side hard line and measured pressure directly from the tee with the passenger side still attached. Reading was about 1500psi. I then removed the passenger side caliper and lines, plugged the port on the tee. Reading was 2500psi.

Might be worth your time to double or quadruple check everything on the passenger side.

For a frame of reference, How are you dealing with the bleeder screws other than cranking down on them?

 

[ntsqd]

By definition AN is 37°, a 45° flare is SAE.

I convert/adapt everything to a male -3AN and then use only straight, 45° Bend and 90° bend female AN swivel hose ends. I don't usually do this at the m/c, only where the flex hose jumps off the frame.

 

[nvrstuk]

Just got home- saw this - more tomorrow & all I can add right now is: (edit punctuation) I ran a 1 1/8" MC with tbird frts and Exploder rears for yrs w/o hydroboost.
Worked flawless, now pedal travel issues and no bleeding issues.

Saying this not to frustrate you but to tell you the volume should work fine for the 1 1/8" cyl.

No idea what it fit as I tossed thst build sheet.

 

[chuzie]

For a frame of reference, How are you dealing with the bleeder screws other than cranking down on them?

Mine don't need cranking. The issue some people have is with the bleeder is open and air is seen in the bleeder hose. This air may just be ambient getting past the threads rather than coming from the system. I find if I place axial pressure on the bleeder it helps reduce/ eliminate the issue.

I ran a 1 1/8" MC with tbird frts and Exploder rears for yrs w/o hydroboost.
...Saying this not to frustrate you but to tell you the volume should work fine for the 1 1/8" cyl.

Good, I need that confirmation so I don't go chasing my tail down another rabbit hole.

No idea what it fit as I tossed thst build sheet.

Ultimately, IMO, if the bore and stroke are appropriate, there's no residual valves and it bolts on, the application shouldn't matter.

If you don't have a tool like this one; buy or make one. It will make setting that push-rod's length MUCH easier.

3D printer came in handy in a pinch. Still gotta match the tip when I pull the MC.

Also gonna go do some pressure bleeding using my garden sprayer; have ports on both sides of the MC and simple to connect a hose.

 

[ksagis]

Mulled on the a bit last night. I’m leaning towards air in lines. Even with the the config that took all of truck out of loop.

When you blocked at MC, did you have slow return pedal? If not, that piece of evidence plus my vague memory of slow return until I got all my air out seems consistent.

Assuming you bled system after configuring for the test shown in this picture. Can you confirm except besides the MC, the bleeder screw was horizontal on the caliper and was the highest point when you bleed? Assuming all those replies are yes, maybe think about trying a gravity bleed for a bit.

Feels like we’re missing something…

 

[chuzie]

... When you blocked at MC, did you have slow return pedal?
... Can you confirm except besides the MC, the bleeder screw was horizontal on the caliper and was the highest point when you bles?

Hell, at this point, I can't confirm squat; too many iterations and now lost in the weeds. Good questions though. I'll run out to the shop to accomplish just to double check.

 

[gnpenning]

Wasn't the problem the bleeder screws not seating properly, not necessarily a thread issue?

 

[chuzie]

Wasn't the problem the bleeder screws not seating properly, not necessarily a thread issue?

Probably a few threads on both issues

 

[nvrstuk]

I re-read this again this am over some coffee (wishing the coffee helped out).

Kind of a summary with a twist.



So, the only items in the system that aren't new are: with a (parentheses) around how you/we have "eliminated" them

- M/C has been (eliminated by pressure readings only), not by volume

- both frt & rear frame to axle flex lines (you've put a caliper on them and you have measured psi farther dnstream w/o psi loss)

- hard lines (ran short hard line bypassing them and tested directly from mc to the caliper) and have measured psi farther dnstream w/o psi loss)



New parts-

-flex lines do not seem to be swelling and your pic shows using a new flex line & a hard line with same pressures w/just the caliper, correct?

-calipers pressure to them has never measured 2500psi

-pads seem correct thickness for application

What's left...

There's not much left as I point out the obvious lol, but in your post #88 we have 3 (possibly 4) items in the circuit, MC, lines to caliper sitting on the fender, and the caliper AND the hydroboost. This pic & test on post #88 eliminates everything else- bias valve, knuckle interference, olf flex lines everything on Bronco except mc, but doesn't eliminate the hydroboost.

It's one of those three (possibly 4) UNLESS there is still air in the caliper and in theory the mc is eliminated because when blocked it produces 2500psi but you have no volume of fluid being moved for this test therefore it could still be the cause.


1- I think it's safe to eliminate the line since you can see it, you've measured it and you've used other lines and the pressure doesn't change

2- you replaced the calipers and have the IDENTICAL results. Pressures measured are within a couple % with new (different calipers)

3- Do you have a different mc laying on the shelf? I can send you a variety of what I have here- all "good" to try. We've all been looking for an increased volume which correspondingly would give us what you are experiencing, a lack of pressure.

#4 Hydroboost mechanical connection. IF you don't have the correct distance between the HB and MC (the pushrod or anything else that would/could cause the mc plunger within the MC to not move enough (faulty HB internals???) thereby not creating the volume needed.
Then you will run out of volume while pushing the brake pedal and therefore the setup can't create enough pressure when trying to move the calipers essentially the volume issue that most have been chasing and Lars mentioned.

What if there is something wrong inside the mc (or inside the HB) so when you get partway thru the stroke it can't create the fluid volume or length of travel of the mc plunger needed? Maybe even like a defect inside the mc where the seals make contact and it won't move any more fluid but the plunger moves the correct distance???

You have excellent pressure #'s when the mc doesn't have to move fluid but when it has to move enough fluid for the caliper to move the pads against your press blocks or against the actual rotor you lose pressure. Correct??

This is essentially what I was chasing years ago with a step differential mc (lack of correct term AstroVan mc at 1.25") and I couldn't create enough volume with the mc so I had to bump up to a 1.33" dia mc and BAM, problem solved in one hour. Mine was volume from mc. Your problem could be problem solve by mc not operating properly or the HB not allowing the mc to have full plunger/piston movement for max volume output.

(note: I have since moved back to a 1.25" mc with the same system it's just not a stepped mc and moves enough fluid for the extra large calipers frt & rear for 3/4ton truck) I did this mainly because I could only solve the leaking lid issue with hose clamps around the lid even with 2 new lids and 3 new gaskets and it was always a big rusty looking pig.

 

[ba123]

+1

That's exactly what I was getting at but you clearly had more patience in writing it out.

 

[nvrstuk]

+1

That's exactly what I was getting at but you clearly had more patience in writing it out.

took over an hour... lol

 

[ksagis]

(note: I have since moved back to a 1.25" mc with the same system it's just not a stepped mc and moves enough fluid for the extra large calipers frt & rear for 3/4ton truck) I did this mainly because I could only solve the leaking lid issue with hose clamps around the lid even with 2 new lids and 3 new gaskets and it was always a big rusty looking pig.

Checking my processing of your posts on this, I had previously understood that the bad line lock combined with 1.25 MC was source of your issues and the 1.33 MC somehow bandaided the issue with the line lock. You subsequently changed the line lock which let you go back to a 1.25 MC and brakes were happy. The new design of MC also didnt leak which since better design.

I have all that right?

 

[nvrstuk]

Checking my processing of your posts on this, I had previously understood that the bad line lock combined with 1.25 MC was source of your issues and the 1.33 MC somehow bandaided the issue with the line lock. You subsequently changed the line lock which let you go back to a 1.25 MC and brakes were happy. The new design of MC also didnt leak which since better design.

I have all that right?

Exactly. If I'd known the line lock was bad that would have saved 3-4 days of anxiety!

 

[chuzie]

Mulled on the a bit last night. I’m leaning towards air in lines. Even with the the config that took all of truck out of loop.

When you blocked at MC, did you have slow return pedal?

Pedal consistently takes an initial jump when released then takes 3-5 seconds to slowly come to rest. This is both with the MC blocked and plumbed. I can only assume it is the nature of this HB or there is air in the HB lines but I haven't observed any bubbles in the PS reservoir.

Can you confirm except besides the MC, the bleeder screw was horizontal on the caliper and was the highest point when you bleed?

I can now confirm that as well as a pressure bleed was accomplished. There is zero air in that circuit, I am 100% confident

I re-read this again this am over some coffee (wishing the coffee helped out).

First and foremost, I want to extend my sincere gratitude and appreciation for the time you, as well as everyone else, have taken to help with this issue. Thank you!

- M/C has been (eliminated by pressure readings only), not by volume

Yes and no. We have confirmed the volume produced by the MC is the same volume yielded at the caliper. The question really is what volume SHOULD we be getting?

New parts-

-flex lines do not seem to be swelling and your pic shows using a new flex line & a hard line with same pressures w/just the caliper, correct?

-calipers pressure to them has never measured 2500psi

-pads seem correct thickness for application

MC is new.
Also currently on HB unit #2. The reason for swapping was not related to performance, but an unrelated defect that has been sorted. Observed the same performance with both units.

...UNLESS there is still air in the caliper

Verified just now via pressure bleed- zero air. 600psi

3- Do you have a different mc laying on the shelf?

I don't, but can easily grab one from a local parts house. Although, these days, maybe not so easily.

#4 Hydroboost mechanical connection. IF you don't have the correct distance between the HB and MC (the pushrod or anything else that would/could cause the mc plunger within the MC to not move enough (faulty HB internals???) thereby not creating the volume needed.

My handy 3D printed measuring tool tells me there's a gap of appx 0.038" at rest between the HB push rod and the MC. Unfortunately, the HB push rod does not appear to be adjustable like the ones on vacuum boosters. I tried twisting it, but there was no change.

You have excellent pressure #'s when the mc doesn't have to move fluid but when it has to move enough fluid for the caliper to move the pads against your press blocks or against the actual rotor you lose pressure. Correct??

Correct
-------------------------------------------------------------------
Now that it's been pressure bled, IMO, only 2 possibilities remain..
1. The 0.038 gap between the HB pushrod and MC is too much:
-- What is an acceptable gap with these HB units?
-- If necessary, how can said gap be adjusted?
-- Could the pill (insert) in the MC piston be milled incorrectly and generating a larger than desirable gap?

2. The new MC is defective or insufficient
-- Is 0.3oz what we should expect to see per pump of a 1-1/8 bore"?
-- Test another 1-1/8 MC

 

[nvrstuk]

Hmmm, at this point an easier test than replacing with the same mc is to go with the MC I have that is 1.25" bore, alum body for no rust, plastic reservoir for no leaks, lines come out on the fender side and is a GM 1 ton unit designed for hydroboost application. I have the part number it's on my build list. I'll grab it for you if you'd like

It would eliminate two possible problems:

- bad mc

- inadequate flow (for whatever reason your system needs/has)


1996 Chev 1 ton M/C for HB on diesel. 1.25” bore installed 5/23 . Calipers are JB7 application for Chev 1 ton trucks frt & rear.

Don't use Oriellys house brand but this Part # NMC90032 will cross reference to an AC/Delco or whatever brand.

 

[chuzie]

Hmmm, at this point an easier test than replacing with the same mc is to go with the MC I have that is 1.25" bore, alum body for no rust, plastic reservoir for no leaks, lines come out on the fender side and is a GM 3/4ton unit designed for hydroboost application. I have the part number it's on my build list. I'll grab it for you if you'd like

It would eliminate two possible problems:

- bad mc

- inadequate flow (for whatever reaseon your system needs/has)

Ya man, send that P/N my way please.
May also try to insert something into the piston cavity to take up 0.020" of that gap just for grins. If anything, it'll give me another excuse to throw tools across the shop.

 

[nvrstuk]

Drill out a washer, concave it to fit the mc end and you can get close to .020".

I'm looking for the brake mc

 

[chuzie]

Drill out a washer, concave it to fit the mc end and you can get close to .020".

I'm looking for the brake mc

Took out 0.032" and zero change in pressure, though slight change in engagement at the pedal as expected.
We can take the actuator rod to MC piston gap off the table.

2. The new MC is defective or insufficient
-- Is 0.3oz what we should expect to see per pump of a 1-1/8 bore"?
-- Test another 1-1/8 MC

Someone check my math and I think it was touched on

When you bleed the brakes, do you get the full displacement of fluid coming out the bleeder? (figure 1-1/8 bore x 1 inch stroke ~ .99 cubic inches of fluid per stroke)

This was mentioned early in the process and I want to circle back around. I know the bore is 1-1/8 but believe CPP told me the stoke was 1-1/8 as well, which means I should be seeing 1.12 in^3 or 0.62oz of fluid per stroke. If that's the case, why am I only seeing 0.30oz? That's 1/2 of what it should be!

Hell, even if we assumed it was a 1 inch stroke, we'd expet 0.99 in^3 or 0.55 ounces, still nowhere close.

Either the specs on this MC are wrong or something is seriously jacked..

The other possibility is I'm a complete buffoon and have no business turning wrenches.