Brakes not releasing.

Suspension, brake, and hydraulic/electric steering discussion.
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Capeasy
Posts: 173
Joined: Wed Aug 07, 2019 9:16 pm
Location: Downey, CA.

Brakes not releasing.

Post by Capeasy »

Anyone experienced there brake peddle getting tighter and tighter and not releasing? Got some traction control fault lights the other night while running the stock size tires( Not my drag radials) I don't think the computer has calculated there's more horsepower and it's working overtime to control the wheel spin. Anyways the lights cleared themselves after cycling the ignition off then on, I checked for DTCs and it didn't show any and just parked the car for a few days. Got in the car today and after a few miles of driving the brakes started getting tighter and tighter, so I first thought it was a caliper hanging up, but all four rotors were just under 290 deg. The brake light stays on so I cracked the two lines coming off the master cylinder to try to relieve any pressure there, but that didn't help either. When the car cools down brakes seem to be OK, the brake peddle has some play but the brake light is still on so some how it's not releasing pressure? I'm stumped:( :(
Walt (AKA:Capeasy) So. Cal.
2013 Caprice 9C1,Huron white, Blackbear tune, DOD Delete, Texas Speed stage 2 cam with all the goodies, Circle D 258 mm converter, 3200 stall. Spectra CAI, 3.45 Diff, deep trans pan. BlackWidow Venom exhaust,Granatelli oval cutouts, Doug Thorley tri-Y headers, Pedders coilovers,Tower brace, Widend OE. rear wheels to 10" wide with 295 Nitto's
GammaFlat
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Joined: Mon Sep 21, 2020 9:26 am
Location: NW Indiana

Re: Brakes not releasing.

Post by GammaFlat »

Totally guessing here.

I would try to pull the TCS fuse to see if you get relief. It's not ABS functionality that's biting you because it's job generally is to "let go". TCS's job is to apply brakes but the puzzling part is that it applies the brakes to individual wheels. I don't believe there's a "apply brakes everywhere" command in TCS systems, rather wheels are braked selectively to regain your "intended line".

I'm not sure if the temp is an indication of problems or not. 290 seems high but I know that "my friend" has put his fingers/hand on rotors of normally operating brake systems that were too hot. :shock:

My method for testing brakes after a brake job is to drive the car and stop. Throw it in neutral and let go of the brake. It seems I'm NEVER on a flat surface (and I live in Indiana :roll: ). If the car don't roll, you got issues. After that, put the car up in the air and hand turn wheels to isolate or confirm that all are problematic.

There are return springs inside the master cylinder/vacuum booster system. Maybe a bad spring? I've never heard of it before but if ever there were symptoms that pointed to it... How many miles on car?
Current: 2013 9C3, deeper trans pan, 12VoltSolutions Remote, Class III hitch, Android Auto capable radio
Pursuit
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Re: Brakes not releasing.

Post by Pursuit »

I'm going to throw a thought onto this, and I'm guessing also. Could one or more of the rubber brakes line broken down on the inside, creating a capillary or "one way" restriction? Not letting the pressure to equalize quickly, within the line, once pressure was applied?

Good luck,

Maurice
Maurice Sheil

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2011 Caprice Phantom Black 9C3
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1995 9C1 Caprice
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Mooseman
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Re: Brakes not releasing.

Post by Mooseman »

Are you able to turn the wheels by hand when jacked up? I'd try cracking the bleeders at each wheel and see if that releases the brakes. If it squirts out and the caliper releases, then something upstream is not releasing pressure. If not, it could be the calipers but it would be very unusual that all 4 would seize at the same time unless there was contamination of the fluid with something else.

Never heard of the ABS module causing this type of problem however have with the master cylinder. Some guys on my truck forum have had issues with new MC's that are not the same piston proportions as the original and contact the booster's push rod too much, pressing the MC's piston. Either they had to modify the push rod or add washers under the MC's mount ears. The MC should go into the booster all the way without having to push on it to press the piston. Because all 4 wheels are sticking, I'd give the MC a thorough inspection.
2011 Caprice PPV, former RCMP test vehicle, never put into service
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Capeasy
Posts: 173
Joined: Wed Aug 07, 2019 9:16 pm
Location: Downey, CA.

Re: Brakes not releasing.

Post by Capeasy »

It's got right at 105K on the car and seems like the original Master Cyl. I cracked the lines loose right at the M/C not much fluid came out, so it dosnt seem like they had much pressure in them if any, but the brake lights were still on. I slowly drove the car back home about 3 miles and slowing the car down with the E brake because every press of the brake peddle created additional drag on the car and the pedal getting harder. After the brakes cooled about 20 min the car seemed to roll a little easier. I'm gonna look into a return spring issue in the booster or M/C. I will also drive it again this weekend and then jack the car up and check each caliper and crack the bleeder as well. Thanks for your recommendations. :)
Walt (AKA:Capeasy) So. Cal.
2013 Caprice 9C1,Huron white, Blackbear tune, DOD Delete, Texas Speed stage 2 cam with all the goodies, Circle D 258 mm converter, 3200 stall. Spectra CAI, 3.45 Diff, deep trans pan. BlackWidow Venom exhaust,Granatelli oval cutouts, Doug Thorley tri-Y headers, Pedders coilovers,Tower brace, Widend OE. rear wheels to 10" wide with 295 Nitto's
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