Brakes overheating after driving a while

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Austin Schlegel

Austin Schlegel

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Hi,

I am new to brakes so please bear with me. I have a 74 dart sport I just bought and it is having brake issues. It has power brakes with single piston discs in the front and drums in the back. I believe the brake system is all stock.

Here's whats happening:
For the first ~10-20mins of driving the brakes work fine with no issues. But after that they start to "stick" or for a lack of better words they slowly start to slow down the car until engine power just wont move it anymore. I have been stuck on the side of the road multiple times due to this. I've had to wait about 30 mins for them to go back to normal and even then the same thing happens after a few mins. Not fun. Theres usually a good abount of smoke coming from the front wheels as well.

I've replaced both front calipers and pads but that did not fix the issue. Any suggestions on what I should check? Or maybe I should just take it to a shop.

Thanks
 
When this happens are all 4 wheels locked up?

Next time this happens pull the vacuume nipple (not just the hose, the nipple has a one way valve in it) out of the Power brake booster, if you instantly have normal brakes the booster is the issue.

I would not keep trying to drive if you start deeling a drag, you can destroy rotors and pads and calipers.
 
Have you replaced the rubber lines? There are 3, two in the front one at the rear. They can swell. Also, fluid, has it been fully replaced? Do your calipers ride on pins or have retaining clips? What condition are the wheel bearings in?
 
Remove the master cylinder and shorten the adjustable rod between it and the booster. My bet is the master cylinder has been replaced at one point. Often times you have to readjust that rod, because not all master cylinders measure the same.
 
You can diagnose it a bit further, I would avoid bringing it to a shop at this point. They might just start swapping out parts and hit you with a large bill. Let's sort through it with Fabo.
If you jack up the front, and the wheels are not able to spin...
Sounds like:
It may be hanging up with hydraulic brake pressure, or
The calipers housings may be hanging up on the spindle surface where they slide back and forth.
 
Last edited:
I’ve seen the rubber flex hoses fail and not release the pressure from the calipers.I’ve seen this happen more then once but never both at the same time.
 
Dana67Dart said:
When this happens are all 4 wheels locked up?

Next time this happens pull the vacuume nipple (not just the hose, the nipple has a one way valve in it) out of the Power brake booster, if you instantly have normal brakes the booster is the issue.

I would not keep trying to drive if you start deeling a drag, you can destroy rotors and pads and calipers.
Click to expand...

I will give this a try next time. I unplugged the hose last time and they just went to power brakes

dano said:
Have you replaced the rubber lines? There are 3, two in the front one at the rear. They can swell. Also, fluid, has it been fully replaced? Do your calipers ride on pins or have retaining clips? What condition are the wheel bearings in?
Click to expand...
I have not replaced rupper lines. I only added fluid to top it off when I replaced the calipers. Ill post a picture of the calipers.

1102211632.jpg
 
RustyRatRod said:
Remove the master cylinder and shorten the adjustable rod between it and the booster. My bet is the master cylinder has been replaced at one point. Often times you have to readjust that rod, because not all master cylinders measure the same.
Click to expand...
I can give this a try

Joey4speed said:
You can diagnose it a bit further, I would avoid bringing it to a shop at this point. They might just start swapping out parts and hit you with a large bill. Let's sort through it with Fabo.
If you jack up the front, and the wheels are not able to spin...
Sounds like:
It may be hanging up with hydraulic brake pressure, or
The calipers housings may be hanging up on the spindle surface where they slide back and forth.
Click to expand...
I can spin them only after its been sitting for a while. If I tried to spin them after driving they will not move. I should also say that the inner pads on both wheels are worn more than the outer ones.

dicksmidlac said:
I’ve seen the rubber flex hoses fail and not release the pressure from the calipers.I’ve seen this happen more then once but never both at the same time.
Click to expand...
I was thinking the same. Not sure why they'd both fail at the same time
 
Take it for a drive and when it starts to lock up, open a bleeder in the front and in the rear to see if there is residual pressure there. There shouldn't be any with your foot off the brake. It will dribble a bit when you open the bleeder, but, it shouldn't spurt out. If opening the bleeder(s) releases the brakes, you have a pushrod adjustment problem where the master cylinder piston isn't returning to it's stop.
 
Contaminated (water) fluid will cause this to happen too. Did the car sit for a long time?
 
FYI, your rotors are junk. It might not be the cause of your problem although if they are warped they might be dragging the pads to the point that the fluid is boiling and the expansion is pushing the pucks out.
 
Austin Schlegel said:
I can give this a try


I can spin them only after its been sitting for a while. If I tried to spin them after driving they will not move. I should also say that the inner pads on both wheels are worn more than the outer ones.


When you say "they" are you talking about just the fronts? You need to keep driving around the block until they act up and get back to your driveway, floor jack and stands to figure out which ones and then release pressure to diagnose. Rear shoes put on backwards (primary shoes to the rear) can self energize.
Click to expand...
 
Just some notes

OP said he can drive for 10 minutes then the problem starts.

OP stated the inner pads are wearing faster.

OP stated that sitting for a few minutes and things release.


I agree with OPs logic that both front flex hoses would fail the same way at the same time seems too coincidental to me.

Im likeing the booster rod adjustment, but why after minutes of driving.

My thinking is the valving in the master cyl is sticking and applying the brakes. I had that happen on a Ford.

The pads wearing oddly sugests there is a reason the caliper is not returning to a free spinning position

Just my thoughts.
 
mcodecuda said:
FYI, your rotors are junk. It might not be the cause of your problem although if they are warped they might be dragging the pads to the point that the fluid is boiling and the expansion is pushing the pucks out.
Click to expand...
With the correct master cylinder and proper push rod adjustment, that won't happen.....in fact, you might get no pedal or braking at all with bad warpage and boiling fluid.
 
Which wheels get hot when this happens? That should tell you which one are the culprit.
 
RustyRatRod said:
Remove the master cylinder and shorten the adjustable rod between it and the booster. My bet is the master cylinder has been replaced at one point. Often times you have to readjust that rod, because not all master cylinders measure the same.
Click to expand...
Was gonna be my response. A check for this being a possibility is after braking stick your foot UNDER the pedal and pull it up every time and see if your "issue" goes away.
 
cudamark said:
Take it for a drive and when it starts to lock up, open a bleeder in the front and in the rear to see if there is residual pressure there. There shouldn't be any with your foot off the brake. It will dribble a bit when you open the bleeder, but, it shouldn't spurt out. If opening the bleeder(s) releases the brakes, you have a pushrod adjustment problem where the master cylinder piston isn't returning to it's stop.
Click to expand...

I just went out and test this, after bleeding the fronts the car can move again easily
 
dadsbee said:
Was gonna be my response. A check for this being a possibility is after braking stick your foot UNDER the pedal and pull it up every time and see if your "issue" goes away.
Click to expand...
Ive tried this and it seems like it relieves some of the braking force but after a while even this does not help
 
RustyRatRod said:
Remove the master cylinder and shorten the adjustable rod between it and the booster. My bet is the master cylinder has been replaced at one point. Often times you have to readjust that rod, because not all master cylinders measure the same.
Click to expand...
I second this ^
I had the same symptoms on a truck, would drive around about 10 mins and brakes slowly locked up. If the piston inside is not fully released then the fluid can't go back into the reservoir as it warms up and expands, so the building pressure causes the pads to drag more causing more heat and thus more expansion.
 
Well at least it's narrowed down to residual hydraulic pressure.
You're getting there.
 
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