Need help confirming or correcting my poor braking diagnosis.

[tpj71mach]

I guess!! BUT if you played a man's game, RUGBY, you wouldn't need to helmet... or padding, just a jock strap and some tape around your ears if you were a forward in the scrum.
Oh, but wait, women now also play Rugby and believe me, those are NOT women to mess with.
Anyway, glad you're making progress on the brakes. I have got to be honest, that's an easy mistake to make, but not hard to fix, just time and more brake fluid. Personally I use DOT 4 in my system with disc brakes.

I played football from fourth grade thru four years of college and then I played two years of rugby and you are right, that was a much tougher game to play. No pads, no helmet, no nothin', it was a lot of fun, but I felt it more the next day than after a football game. Maybe that's where I got my dain bramage, LOL. Two years was enough, I hit 24, I had a mortgage, a fiancee, and I realized I need to get to work on Monday mornings. I needed to stop certain things like rugby, rock climbing, repelling, moto-cross and grow up a little.

 

[basstrix]

The bleeder should point to the REAR of the car. If they're pointing up, you'll never get the air out - first hand experience showed me that.

I would swap the calipers side to side, re-bleed and see if you still have the sinking pedal.

View attachment 80664

I'm glad you clarified with a picture.

 

[mrgmhale]

Lots of good suggestions have been given. Although it may not hav anything to do with your current soft pedal issue, I would suggest you consider replacing the two front, and one rear (shared) rubber hydraulic brake hoses. At 50+ years old (unless replaced already) it is time to get some new hydraulic lines in place before there is a sudden and forceful pressure sent to them. I had made this suggestion to another enthusiast a while ago, then decided it was high time to replace the hydraulic lines on our three vintage pony cars - before having one rupture due to weakness with age and external cracking. I ended up ordering them through AutoZone.com for just over $200 for all three sets of hoses and retaining clips.

Aan aside FWIW, although technically DOT 3 and DOT 4 brake fluids can be mixed it is not what I am going to do. %ot 5.x s the same for me, no mixing with GOT 5.x brake fluid. The Master Cylinder states DOT3, which is plenty adequate. So DOT 3,0 it is. Nit nixing with other fluid tyoes helps kjeep things simple, no room for confusion.

 

[tpj71mach]

Lots of good suggestions have been given. Although it may not hav anything to do with your current soft pedal issue, I would suggest you consider replacing the two front, and one rear (shared) rubber hydraulic brake hoses. At 50+ years old (unless replaced already) it is time to get some new hydraulic lines in place before there is a sudden and forceful pressure sent to them. I had made this suggestion to another enthusiast a while ago, then decided it was high time to replace the hydraulic lines on our three vintage pony cars - before having one rupture due to weakness with age and external cracking. I ended up ordering them through AutoZone.com for just over $200 for all three sets of hoses and retaining clips.

Aan aside FWIW, although technically DOT 3 and DOT 4 brake fluids can be mixed it is not what I am going to do. %ot 5.x s the same for me, no mixing with GOT 5.x brake fluid. The Master Cylinder states DOT3, which is plenty adequate. So DOT 3,0 it is. Nit nixing with other fluid tyoes helps kjeep things simple, no room for confusion.

Thank you. I agree that the three rubber lines should be replaced as I did because as the rubber ages they can burst or deteriorate inside and collapse and restrict brake fluid flow. All of my hoses were replaced, along with all of the other components in the brake system when I started to reassemble the car after media blasting and painting the shell. I also agree that if DOT3 is what the car was engineered for then that's what needs to be used. I believe the problem that I am experiencing is because, as Hemi-Killer identified, I installed the calipers on the wrong side and the bleeders are in the wrong position to allow proper bleeding. I plan to swap and re-bleed as soon as I can. Unfortunately, this weekend is pretty booked up, but I am hoping to squeeze it in an early morning before we head out for the day's activities.

 

[Hemikiller]

I'm glad you clarified with a picture.

I created that graphic a few years ago after a particularly raucous discussion on the same subject in a FB Mustang group. The naysayers weren't swayed, even when the guy having the problem came back and said he had mixed them up and his problem was fixed.

 

[Stanglover]

Thank you. I agree that the three rubber lines should be replaced as I did because as the rubber ages they can burst or deteriorate inside and collapse and restrict brake fluid flow. All of my hoses were replaced, along with all of the other components in the brake system when I started to reassemble the car after media blasting and painting the shell. I also agree that if DOT3 is what the car was engineered for then that's what needs to be used. I believe the problem that I am experiencing is because, as Hemi-Killer identified, I installed the calipers on the wrong side and the bleeders are in the wrong position to allow proper bleeding. I plan to swap and re-bleed as soon as I can. Unfortunately, this weekend is pretty booked up, but I am hoping to squeeze it in an early morning before we head out for the day's activities.

DOT 3 and DOT 4 are ordinary brake fluids, just higher temps for DOT 4. DOT 5 is silicone based and therefore not compatible with DOT 3 or 4.
I would think maybe DOT 4 didn't exist when our 50+ year old cars were engineered. I run DOT 4 with 4 piston disc brakes up front.

 

[tpj71mach]

I created that graphic a few years ago after a particularly raucous discussion on the same subject in a FB Mustang group. The naysayers weren't swayed, even when the guy having the problem came back and said he had mixed them up and his problem was fixed.

The graphic really helps visualize why it is so important to get it right, from the outside of the caliper it doesn't appear to be such a difference. Thanks again.

 

[mrgmhale]

@giantpune "With him saying the pedal slowly sinks to the floor, that just about has to be the master cylinder leaking internally. "

Yes I think so too... I mentioned the booster because his been rebuild. I had a similar case when I've replaced my 73 booster 2 or 3 years ago, by a smaller one from Leed. The rod was set too far away. and while somehow the pedal was not really going down on its own, prolly due to the membrane, breaking power was near zero. Basically I was barely pushing the piston, and when I was, the pedal was not having enough travel left to push more.

"They sell a kit for this at the parts store."
I thought so... you guys are so spoiled!!

The pedal sinking to the floor when there are no external leaks is a definite sign of the Master Cylinder sup seal(s) leaking internally. When rebuilding the MC be sure the MC bore is honed and has no pitting. If you are placing it be sure to get the proper piston diameter and brake fluid bowl capacity - especially if you have disc brakes. Also, if you have disc brakes make sure the Residual Pressure Check Valve (RPCV), typically a small flapper valve under the our port(s) brass seat, is not present. You only want the RPCV to be present for the port(s) sending brake fluid to drum brake wheel cylinders. If the RPCV is used with a disc brake caliper, there will be a constant pressure applied the affected calipers, which will cause the disc pad to drag on the rotor. That will result in reduced vehicle performance, reduced fuel economy, excess wear of the disc pads, and overheating/warping of the rotors.

 

[mrgmhale]

DOT 3 and DOT 4 are ordinary brake fluids, just higher temps for DOT 4. DOT 5 is silicone based and therefore not compatible with DOT 3 or 4.
I would think maybe DOT 4 didn't exist when our 50+ year old cars were engineered. I run DOT 4 with 4 piston disc brakes up front.

I agree in general with your assessment about DOT4 brake fluid. If I were tracking the pony car I would choose to use it to help prevent brake fluid boiling. But, these are street cars, seldome friven, and never driven hard. So I do not need the higher boiling point of DOT4. DOT 3 does the trick just fine.

 

[Stanglover]

I agree in general with your assessment about DOT4 brake fluid. If I were tracking the pony car I would choose to use it to help prevent brake fluid boiling. But, these are street cars, seldome friven, and never driven hard. So I do not need the higher boiling point of DOT4. DOT 3 does the trick just fine.

As you wish, your choice.

 

[cwalker509]

Not sure this is helpful but it is a similar experience. New MC installed and brakes vacuum bled multiple times because they never pumped up. Rear disc and wilwood disc up front (used a 4 wheel disc prop valve). Pedal still went to floor and could not pump up. Bought another MC and it works so far. Pumps up but engine not installed yet so no final acceptance. I have not done any type of failure analysis on the new but nonfunctional one. Prretty much has to be the MC piston arrangement is bad. Scored o-ring or bore messed up but not sure I really care at this point, lol.

 

[mrgmhale]

I created that graphic a few years ago after a particularly raucous discussion on the same subject in a FB Mustang group. The naysayers weren't swayed, even when the guy having the problem came back and said he had mixed them up and his problem was fixed.

I, for one, am very glad you created that graphic. I is the very best depiction of what happens when calipers are swapped onto the incorrect side. I hope you do not mind that I have, time after time, hijacked that very graphic when trying to help folks out with an unbleedable brake system. If you like I can begin to give credit where credit is due with my postings that include the caliper graphic.

And, yeah, you rock! Your considered responses to others are always spot on. I fancy myself to be quite familiar with these old pony cars. But, I also feel I stand in your shadow - which is a good thing as I continue to learn from your recommendations, thoughts, and sage advice.

 

[tpj71mach]

I found some time over the weekend and swapped the calipers to their correct side of the car. I bled the brakes and tested and there is a nice stiff pedal and it holds. I road tested and the brakes actually work, yay! I attached before and after pics, you can see the bleeder is pointing up in the before pics and to the rear of the car in the after pics. Thank you to HemiKiller, Giant Pune, Fabrice, Sheriff, Stanglover,Cwalker and Mrgnhale for all of your help. Hemi Killers diagram really clarified why what appears to be a minor difference on the outside is in reality a game changer.

 

[mrgmhale]

I found some time over the weekend and swapped the calipers to their correct side of the car. I bled the brakes and tested and there is a nice stiff pedal and it holds. I road tested and the brakes actually work, yay! I attached before and after pics, you can see the bleeder is pointing up in the before pics and to the rear of the car in the after pics. Thank you to HemiKiller, Giant Pune, Fabrice, Sheriff, Stanglover,Cwalker and Mrgnhale for all of your help. Hemi Killers diagram really clarified why what appears to be a minor difference on the outside is in reality a game changer.

I am gladyou were able to proper;y bleed the brakes after swapping the calipers. And, yeah, HemiKiller rocks. I lifted his graphic a while ago, not knowing he was the person who created it at first, and have provided that to others who were also bittenby the cross swapped caliper demon. I have let him know I have been distributing it, and so far he has not told me to stop using it. I do not ever make claims re: having created it, but I think on a Go Forward basis I am going to let folks know he is the creator of the graphic. It is only right to give credit where credit is due. It has definitely been useful.

 

[Fabrice]

You got to admit Ford did poor design on this. By just moving one bolt hole inwards into the casting and the bracket this would never be possible...

 

[giantpune]

You got to admit Ford did poor design on this. By just moving one bolt hole inwards into the casting and the bracket this would never be possible...

Or by casting a big fat R and L onto each one of them.

 

[Hemikiller]

Cost savings - same casting, side specificity depends on how it's machined.

Ford used these on the 68-73 Mustang/Cougar and the 68-71 Falcon/Comet/Fairlane/Torino/Montego lines. They probably made millions of these calipers, so a $.10 savings adds up.

 

[351c1971]

Just between us girls, I did the same thing about 5 years ago