Brakes Front brakes heating up, pressurizing fluid, pedal stays up

Mustang5L5

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Mod Dude
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Yes. With the bleeder open, you should be able to push the piston in with your hands. It will take some effort, and go slowly, but it should move and you should see fluid come out of the bleeder.
 
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MRaburn

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OK, I could not get it to go in with my hands, both pushing. The caliper piston was barely out since these are new pads. I left the bleeder open and took a C-clamp and with very little effort turing the clamp, the piston did go in and fluid came out of the bleeder.

Not sure at this point now.
 

General karthief

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Nope, nothing missing, there is a slight amount of drag on the rotor, very minute, install the caliper with the pads, push on the brake peddle a couple times (bleeder closed of course) then try to spin the rotor, it should turn with little effort. If it does you may have to drive the car to build up some heat to cause the caliper to malfunction.
A few possibilities for this situation, bad caliper, hose or the prop valve has junk in it.I
This is my opinion based on experience and not on any real mechanical ability.
 
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7991LXnSHO

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In addition to the Generals experience suggestions, does the caliper slide over the pins ok without the rotor? There are always farther out possibilities like wrong thickness pads or the wrong rotor causing the drag or the caliper ior mounting points being off.
Anyway, do not press the pedal hard without the caliper installed. Now you know the caliper piston goes back in with the bleeder open, seeing if it will go back in with the bleeder closed is the next step. If the piston goes out with pedal pressure and it does not go back in without a lot of C clamp force, there is an almost complete block in the system.
 
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MRaburn

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This is fun... hah. I appreciate you guys opining and offering help....

OK, so the left piston pin, its hard to push into the caliper and real hard to get out, as in... it is the problem. Its dry as a whistle. What grease is appropriate if you think that will even help. Maybe just a bad caliper?

There is no way for the piston/pad to relax when I let off, this pin really feels wedged in there and takes good effort to pull it back out.

Mike
 

MRaburn

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OK I think it's the Pin itself. The other pin acts normal in both bolt holes with little resistance, a little grease and it would be happy. The other pin will not place nice in either hole, like its oversized. Weird.
 
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TOOLOW91

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Does anyone make aftermarket calipers like Wilwood that will bolt in place on these old 4 lug setups?
Baer i know does. They have a nice sealed unit 4 lug rotor as well. I have a dealer if that is a route you decide to go.
 

Mustang5L5

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Stick a block of wood in the caliper. Zip tie it or wire it in place. Then you can slowly press on the pedal to force the piston out a bit to see if it is coming out and not worry about the piston shooting out. It will stop on the wood.

you can buy that pin separately. Usually come on a caliper hardware kit.

edit: plenty to choose from
685D0B5C-9C63-4985-AC6F-70BB1FCE5452.png
 

MRaburn

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These pins act as pistons too correct? They are forced in and the air pressure from the nipple allows it to slide back out. Maybe these pins are just do dry. I'll test greasing these pins up and see how they act. I'll order some new pins as well to get the process started.

Mike
 

MRaburn

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For those who want to see what Im working on if peaking in on the thread....
 
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7991LXnSHO

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Ya, they dont look real straight to me as I was looking at them... I was like surely not. Heh.
That’s the pain with remote diagnosing. I figured you had new or good hardware.
Caliper pins are one of several things that don’t work so well bent, especially sliding ones.
 
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MRaburn

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Ya it's all new hardware, which I know means nothing. heh. From the naked eye they do not seem 'bent' but my eyes are saying something is not right. I'll roll them on a flat surface tomorrow to see what I get. I went ahead and ordered new pins and grease and pick them up Monday. Will do the drivers side as well just to address any and all.
 

MRaburn

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OK, tried different things and still same result. I talked to a few other people and also @Noobz347 about my tests and we think for sure that passenger side caliper is just bad.

  1. I put the new pins in well greased.
  2. Cranked the car, applies brakes. Turned off car.
  3. Right rotor was seized, could not turn by hand.
  4. Release the bleeder valve to start a test and no fluid came out.
  5. Removed the new pins from the caliper. Still could not turn the rotor.
  6. Removed the caliper to take off the J&M brake line. No fluid came out of it from disconnect on caliper side.
  7. Broke the fitting lose at the frame metal line to the J&M line and the fluid flowed out of the JM line as expected till emptied.
  8. Put a tube on the metal line and applied brake pumps several time to see the fluid come out clear and no trash.
  9. I could push the caliper piston in by hand once I had disconnected the main brake line.
So thoughts are bad caliper. I would also like to replace the master cylinder to a new style, as its the factory old style. The master was a reman from Oreillys a few years back (no part number to provide) and the calipers were just a reman kit from LMR, they currently show these out of stock on their site.

@Mustang5L5 suggestions?

Quality source for reman calipers and a modern style master that fits current fittings etc? I do not really want to spend the coin on a Brembo front Big Brake kit for 15" wheels... $1700. :O_o:

I also have an 89 LX proportioning valve here I took off my BTC project that could get swapped in as well, so maybe a new master cylinder, prop valve and caliper.
 
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Mustang5L5

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You have the brake line off right now? Can you pour a liquid from one end and get it to flow to other side easily just due to gravity? Try it from both directions. You can use water, just blow it out and let it dry before you reinstall.

If it does flow, replace the caliper. Any parts store reman should be ok. These days most are done by Cardone anyway. I usually grab Raybestos.

as for the newer MC, you’d want a stock 87-93 MC, but the fitting sizes are different. It’s a 3-port MC, where you have a 2-port. Also, the ports are metric bubble flare, while you have SAE inverted flare. So it would take some new lines and adapters to put a 3 port mC on the older 2-port cars.

Ill take a peek at the Max motorsports site and see if they offer any adapters I thibk would work. However if you even planned on rear 4-lug disk, now is the time
 
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MRaburn

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I am planning for rear discs... but not a tomorrow thing. Sourcing parts might be hard right now, a lot of suppliers are struggling with Covid demands due to all of us sitting at home wrenching.

But I can entertain the idea if you guys can steer me the right direction. Change it all over, I have flare tools too and could convert some line ends as well as needed.

Ill test the brake line in the morning, it's a brake line that J&M made me. He made me these lines as a one off on request and said the crimper could have not been set right.