Brakes locked up - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JayDubBlazer · 05-21-2004, 06:10 PM

I just bleed my brakes and backed it uabout 30 ft. I pressed the brakes and then they locked up. I believe it to be the front discs. Any help would be apprecieated.

jku72 · 05-21-2004, 06:44 PM

I'm only guessing, but I'd say that there is a problem with the fluid return to the master. There are several reasons for this, and for a more accurate diagnosis, it would be good to know why the brakes were bled. New parts? Which ones?
Any way, the two reasons for this that i can think of off the top of my head are:
1. Brake pedal/ rod out of adjustment. in other words, the brake piston in the master cylinder is not being returned to its normal position. This means the return ports are not getting uncovered, so the brakes will be stuck on.
2. Dirt clogging the return port, this to me would on ly be likely if an old master was used, or the brake system had been empty for a while, so rust could form.
3. Okay, I just thought of a number 3, perhaps, if you have power brakes, the vacuum diaphram check valve might not work so well, this is usually indicated by the pedal staying dowwn.
4. Oops, they keep coming. If there was a stuck caliper this could do it.
5. Forget counting. If its in the rear brakes, and you had it disassembled, the brake adjuster could be in backwards, and any sort of forward motion is going to cause the brakes to over tighten. This happened to me once. It was very difficult to remove the brake drum because my brakes were so over adjusted.
Like I said, more info would make a diagnosis easier.

JayDubBlazer · 05-21-2004, 07:36 PM

it let go. But I relplaced the rear shoes and turned the drums. It was the front calipers that were locked up. I let it sit for a while and my father pushed it and it rolled. I don't know what happened. It is a newer master and the front pads were replaced last year.

Longhorn Man · 05-21-2004, 11:38 PM

Get the fronts to lock up again (I'm asuming they remained locked up after you took your foot off the pedal?) Remove the wheel and loosen the bleeder. If the caliper releases it's grip, then your problem is not the caliper...some where in the rubber line, hard line, or master cylinder.
If it repains locked up, it's time of a caliper.

05-21-2004, 06:10 PM	#1
JayDubBlazer go cyclones Join Date: Jun 2003 Location: Ames, IA Posts: 1,885	Brakes locked up I just bleed my brakes and backed it uabout 30 ft. I pressed the brakes and then they locked up. I believe it to be the front discs. Any help would be apprecieated. __________________ Wes PROJECT OLE GREEN 1972 Blazer 4X4 350/700R4 2017 Silverado LT

05-21-2004, 06:44 PM	#2
jku72 Registered User Join Date: Jan 2002 Location: cornville, maine Posts: 659	I'm only guessing, but I'd say that there is a problem with the fluid return to the master. There are several reasons for this, and for a more accurate diagnosis, it would be good to know why the brakes were bled. New parts? Which ones? Any way, the two reasons for this that i can think of off the top of my head are: 1. Brake pedal/ rod out of adjustment. in other words, the brake piston in the master cylinder is not being returned to its normal position. This means the return ports are not getting uncovered, so the brakes will be stuck on. 2. Dirt clogging the return port, this to me would on ly be likely if an old master was used, or the brake system had been empty for a while, so rust could form. 3. Okay, I just thought of a number 3, perhaps, if you have power brakes, the vacuum diaphram check valve might not work so well, this is usually indicated by the pedal staying dowwn. 4. Oops, they keep coming. If there was a stuck caliper this could do it. 5. Forget counting. If its in the rear brakes, and you had it disassembled, the brake adjuster could be in backwards, and any sort of forward motion is going to cause the brakes to over tighten. This happened to me once. It was very difficult to remove the brake drum because my brakes were so over adjusted. Like I said, more info would make a diagnosis easier. __________________ jku Cornville, Maine 68 C10 burb 42 Willys MB 46 Dodge WF-32 1.5 ton 53 & 56 Olds' 60 Cadillac 22 Dodge Brothers

05-21-2004, 07:36 PM	#3
JayDubBlazer go cyclones Join Date: Jun 2003 Location: Ames, IA Posts: 1,885	it let go. But I relplaced the rear shoes and turned the drums. It was the front calipers that were locked up. I let it sit for a while and my father pushed it and it rolled. I don't know what happened. It is a newer master and the front pads were replaced last year. __________________ Wes PROJECT OLE GREEN 1972 Blazer 4X4 350/700R4 2017 Silverado LT

05-21-2004, 11:38 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Get the fronts to lock up again (I'm asuming they remained locked up after you took your foot off the pedal?) Remove the wheel and loosen the bleeder. If the caliper releases it's grip, then your problem is not the caliper...some where in the rubber line, hard line, or master cylinder. If it repains locked up, it's time of a caliper.



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