Why are my brakes locking up and getting hot?

Tiny
MCJR
  • MEMBER
  • 2002 CHEVROLET SUBURBAN
  • 91,000 MILES
After driving vehicle for a short time, both rear calipers will not fully release and have a drag on rotors. It will get worse as you drive until the rear brakes, rotors and rim are very hot and brakes are giving off a burning smell. I have duplicated issue and jacked up and find both rear tires hard to turn by hand, removed tires and removed caliper slide bolts and had to remove caliper from rotor by prying off with screw driver. After vehicle sits for 15-20 minutes, the pressure will relax.
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Tuesday, June 5th, 2012 AT 3:34 PM

61 Replies

Tiny
MCJR
  • MEMBER
This happens when the brake booster push rod is adjusted out too far which does no allow the brake master to return fully holding the brakes on. To confirm the issue loosen the brake master mounting bolts 3 turns to see if the car starts to roll again, if so remove the master and adjust the booster push rod inward. Check the caliper slide pins have been removed and greased, there appears to be no crimped brake hoses. I am being told it could be the calipers, brake hoses, master cylinder, etc. How is the best way to trouble shoot this so I am not throwing parts at it?
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Tuesday, June 5th, 2012 AT 3:36 PM
Tiny
DRCRANKNWRENCH
  • EXPERT
It is probably the pins. They are made for the caliper to move back and forth on and can get gummed up or bent. More than likely they just need cleaning and greasing.
Get some brake cleaner and some paper towel type shop towels and some high temp axle grease.
Clean the pins and the holes they travel in completely. Inspect for large bends then put a little grease on the o rings if applicable. See if the caliper will slide freely on the pins. If so, grease them up a little more, make sure they bottom out because too much grease will keep them from going all the way in.
Make sure dirt boots are in place and don't have tears. Check for movement againa and then install.
Test drive and check for operation.
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Tuesday, June 5th, 2012 AT 4:16 PM
Tiny
MCJR
  • MEMBER
Have already cleaned and greased the pins and holes they travel in. There is pressure on the rotors from the calipers unitil vehicle sits for a short period of time and then they free up again until you drive for a short period of time. So I checked the booster push rod and then adjusted it inward, fixed the problems thank you.
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Tuesday, June 5th, 2012 AT 5:04 PM
Tiny
HELLOHIWELCOME
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 238,700 MILES
The brake on the front left driver side is locking and the rotor is glowing hot red and pulling to the left. The other brakes seem fine.
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Monday, March 15th, 2021 AT 11:32 AM (Merged)
Tiny
CARADIODOC
  • EXPERT
Open the bleeder screw to see if that caliper releases. If it does not, replace both calipers for even braking. If it does release, the next time crack the steel line open at the master cylinder. If the caliper releases there, suspect the brake fluid is contaminated with petroleum product. That will be a REAL expensive repair. If the caliper doesn't release from the master cylinder, suspect the rubber flex hose is coming apart inside and acting like a check valve for the brake fluid.

My guess is that fluid contamination isn't the problem because both calipers would typically be dragging at the same time.
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Monday, March 15th, 2021 AT 11:33 AM (Merged)
Tiny
ANNWHIT
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • 96,000 MILES
Both front driver and passenger brakes stick and will not release the wheels get real hot cant touch. Have gotten so hot they melted ABS wires so had to replace them.I have replaced the brake pads, calipers, rubber brake lines and master cylender new break fluid. What could it be.
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Monday, March 15th, 2021 AT 11:33 AM (Merged)
Tiny
CARADIODOC
  • EXPERT
Next time they lock up, loosen the steel lines at the master cylinder. If that lets them release, the brake fluid was contaminated with a petroleum product. That will be a very expensive repair. If that appears to be the cause, get the brakes to lock up again, then loosen the mounting nuts for the master cylinder and pull it forward from the power booster 1/8". If THAT lets them release, check the adjustment of the brake light switch or for something else holding the brake pedal down a little.

If loosening the lines at the master cylinder doesn't help, loosen them at the ABS hydraulic controller. If that is what's holding the brake fluid under pressure, replace the controller.
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Monday, March 15th, 2021 AT 11:33 AM (Merged)
Tiny
ANNWHIT
  • MEMBER
Why can't I bleed the back lines
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Monday, March 15th, 2021 AT 11:33 AM (Merged)
Tiny
CARADIODOC
  • EXPERT
What are you doing or what isn't working? Are the bleeder screws plugged with dirt? Does brake fluid come out if you push the brake pedal?
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Monday, March 15th, 2021 AT 11:33 AM (Merged)
Tiny
ANNWHIT
  • MEMBER
Put new master cylinder on bleeding brakes then back ones just quit pushing out fluid. I adjusted the booster rod works now.
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Monday, March 15th, 2021 AT 11:33 AM (Merged)
Tiny
PORSCHE962
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 168,500 MILES
I just noticed recently that a burning smell was from the left front whell, and touching it was very hot. So I know that the pad wasn, t coming off properly. Is this a electrical/hydraulic problem, or just a pad problem. The brakes were done a year ago by gm. Also why do the brakes grab hard after sitting a few hours after rain or foggy days.
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
The brakes are hydralic. As far as the one that seems to be overheating, make sure the caliper piston and the slides are moving properly and not sticking. If they are good, check the black rubber hose that connects to the caliper. Over the years, they break down inside. As a result, they don't release the pressure from the caliper. To check that, pump the brakes to see if the caliper sticks. If it does, loosten the bleeder to see if once the pressure is released the wheel spins freely.

As far as the touchy brakes, this is a common problem. What seems to happen is a glaze builds up on the rear drums and shoes. That combined with moisture causes them to grab. Chances are the problem stops after driving a short distance, but it is a pain. The only fix (and it's temporary) is to sand the brake shoes and have a very light cut done on the drums to eliminate the glaze in them.

Let me know what you find and if this helps you.

Joe
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
MICHAEL MULVANEY
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 141,000 MILES
This is a K2500 with 7.4 liter. The driver's side rear wheel seizes when brakes are applied on gravel or snow covered surfaces. All pads, shoes, and rear axel seals have been replaced in the past 300 miles. This problem existed before replacement and hasn't changed. Having repaired my cars for the past 45 years, I suspected a brake proportioning valve but have been unable to find a part or even a schematic of the system. Thanks, Michael
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
BUDDYCRAIGG
  • MEMBER
Are you sure the primary was on front and the secondary was on the rear when the shoes were replaced?
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
MICHAEL MULVANEY
  • MEMBER
Sure as I can be without taking it apart. Any other ideas? Michael
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
BUDDYCRAIGG
  • MEMBER
Well you wouldn't have to take it completely apart, just the wheel and drum.

I don't expect a proportioning valve to be the problem.
Most RWD vehicles have one main line going to the rear brakes, the T off to each side. So equal pressure would be going to both wheel cylinders. (Although I do not have a hydraulic schematic for your truck either).
I could see a smashed line going to the other side keeping fluid from getting to it, and then too much fluid going to the side that's locking up.
Do you remember if both sides were wearing about the same?

Might try putting it on jack stands and run it in gear. Have someone slowly depress the pedal and see both rears will actually stop turning.

I just can't get the idea out of my head that the secondary is on the front and causing it to over-energize.
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
MICHAEL MULVANEY
  • MEMBER
This isn't a RWD it is a FWD with a full floating rear axel, a K 2500. I'm not sure if this makes a difference, you will have to tell me if it does or not. Michael
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
BUDDYCRAIGG
  • MEMBER
Give me the last 8 digits of your VIN.
You can send it to me in PM if you are not comfortable with posting it on the internet.

PS, I have to leave in 90 minutes to watch my son while my ex goes to an appointment.
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
BUDDYCRAIGG
  • MEMBER
I want to explain why I need the last 8 digits of you VIN.
Back in the old days when we used parts book and micro fiche to look up parts.
We had to ask all sorts of questions.
Say you wanted the Yoke on the front of a drive shaft.
If you had an automatic, you needed page I-17,
If you had a manual, you needed page G-20
If you had and extended frame and a 2-piece shaft, then you needed page H-12.
So if I (the parts guy) didn’t ask the right questions, or know where to look, I could possibly sell you the wrong part.

The new computers and parts programs take the human error factor out of it.
If you have VIN 123456, then the computer knows you have an Auto with a once piece drive shaft and thus only give me access to the correct page.

So the VIN is the “key” to unlocking the parts program.
Without it, the computer is just a dumb box. And will not let me look at anything.

I want to pull up a picture of your brake plumbing.
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Monday, March 15th, 2021 AT 11:34 AM (Merged)
Tiny
MICHAEL MULVANEY
  • MEMBER
Sorry to get back so late on this but I had connectoin issues. The Vin # is XJ505465. Thanks Michael
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Monday, March 15th, 2021 AT 11:34 AM (Merged)

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