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

MRaburn

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@Mustang5L5, I was told you were the guy to ask. :p

Trying to finish up my 86 project. Having brake issues.

I replaced front suspension, bearings, rotors, calipers, lines, and master cylinder. Didnt touch the rear drums.

When driving, the front rotors are heating up to the point where if I put a hose to them they would steam. Under no braking, as in driving down a highway, when it comes time to stop, the pedal is solid, as in I cant push it down at all, as though the fluid heated up, expanded and the breaks are already at full expansion, and when I try to stop, I have to push real hard on the pedal as though I was driving with manual brakes and the pedal will only move about 1". It takes a bit to stop.

I have to assume the calipers are not opening back up and the pads are riding on the rotor and generating heat.

Any ideas? The calipers are just simple repops from LMR and the rotors are from Stoptech. I would like to find some upgraded calipers like Wilwood, but want to keep the stock spindle and 4 lug.

Thanks guys! My resto project is almost done!

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PS. No the Bronco in the background is not for sale :)
 
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Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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First thing would pop into mind would be booster pushrod adjustment. If it is protruding too far, it causes the front brakes to drag and not fully release.

it could be the calipers themselves, but unlikely both would be stuck at the same time. That usually points to a common issue like MC or booster rod.

with the front wheels off the ground, do they turn freely?
 

MRaburn

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Mike,

I've got to go on vacation this week, so when I get back it is going on the lift. I will keep you posted with what a find.

FYI, before I replaced all the brakes, when I first started driving it again after it had sat up for several years, the front brakes were completely locking up and dragging the front wheels on my gravel driveway. So I told myself maybe the calipers were stuck and replaced them along with the rotors, bearings. Before that I had replaced the master cylinder because I had NO brakes, pedal to the floor. Now the pedal is at the top and still heating them up, although they are not locking up (yet).

I was thinking I could replace the booster and the master cylinder again. Any thoughts on the proportioning valve?

I'll post an update in a week when I get the wheels off on the lift.

Thanks
Mike
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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I have seen a PV rust up inside, but the brake system on the car was nasty. Prob never changed since the 80s and full of fluid. Upon opening the combo vskve, it was a rusty mess. There were signs as to what I was going to find however. For the most part, most of the ones I’ve dissected have been ckean. So if you suspect there may be internal corrosion, you can certainly pop the front plug off and take a look. Should be pretty obvious if it’s corroded in there.
 

HemiRick

I'd be looking at jacking under the house
Jun 28, 2020
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Are the brake hoses original? old brake hoses can swell and clog up internally, causing the brakes to drag.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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Are the brake hoses original? old brake hoses can swell and clog up internally, causing the brakes to drag.
 

7991LXnSHO

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Tell us if Goofy wears a mask
Inquiring minds want to know.
Since your brake questions are hopefully answered, here are questions for the trip.
If Goofy and the mice are wearing full head masks, does that count? Do Sleeping Beauty or Snow White have to wear masks while cursed and sleeping? And has Prince Charming been tested?
 
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MRaburn

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@Mustang5L5

Ok here is an update and Im confused as to what the problem could be.

Backstory: When I got the car it had no brakes, foot to the floor and pray to stop. So I replaced the master cylinder knowing it was probably just done with bad valves and rings, etc. As soon as I replaced it and started to drive the car after it had been setup for a few years, the front brakes were grabbing and not letting go... as in on my gravel driveway they would be locked up and drag as the rear wheels pushed the car. So then I was like OK the calipers are shot, so I replaced those. While I did this I replaced all the bearings, rotors and calipers and pads. I did a quick short test drive, all was well, pedal was at the top and stopping.

Let several months go bye while Im finishing the build. This is when I noticed that something was wrong. We drove about 10 miles and could smell the brakes and the pedal got hard and at the top as though there was no mode fluid to push because it was getting hot and expanding.

OK jump forward to today to start what everyone suggested that the pushrod could be pushed in too far. On taking things apart, it appears that the passenger side is the one that was acting up, the paint on the hat and edges of the new rotor were baked off and cracking off. This is where it was getting hot. I could not easily free spin the rotor, it took effort to get it to turn. The drive side would turn and free spin if I gave it a try, so it did not appear to be sticking. So I then unbolted the master cylinder and pulled it away from the pushrod and booster, so there was no pressure on it to be pushing against the brakes. Well the passenger side would still not spin freely, it was still binding, you could feel the calipers dragging on the rotor. So I took the top part of the caliper off with the pads, and the spindle will spin freely with ease.

What to do? Whats keeping pressure on this caliper?

Mike
 

7991LXnSHO

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It sounds like a stuck caliper or clogged hose or line. At this point, new hoses are a good idea when you check the system for brake fluid flow. The mentioned it above, but it’s a standard step in a vintage car group, which I have been reminded these are now.
 

MRaburn

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I put new hoses on during this install, but I was reading a thread about the pins, they are not lubed but slide in and out easily. I know I should lube these up now but could that have been the problem to start on brand new calipers?
 

Mustang5L5

Put lubricant all over the balls
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Feb 18, 2001
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On the wheel that’s dragging, Jack it up, hook a hose to the bleeder and crack the bleeder open. Does the caliper free up then? If not, I’d replace the caliper again.

stuck pins usually wear the pad away fast and then the wheel spins freely. You’d also notice one pad is wearing down much faster than the other side. Classic stuck pin telltale sign.
 
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MRaburn

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Ive got it apart right now, so pads are not in caliper. So if I crack the bleeder open, what should I see the piston do? Can I push in with my hands. The car is on my lift right now.