Front Brakes LOCKED! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Chevy Iron · 03-11-2012, 10:13 PM

Replaced the master and have the same issue. Third time on the brake pedal, the fronts are dragging and continue to do so until they are locked (all parts are new).
Opening the line at the master cylinder releases all pressure on the calipers.
Any advice? Thanks guys.

72freak · 03-11-2012, 10:27 PM

Any time I have locking brakes its the brake hoses collapsed.

oldspowered67C10 · 03-12-2012, 04:36 AM

Check the length of the push rod between the booster and the master cylinder(assuming this is power set-up). If the rod is too long it wont allow the pressure to bleed back when you release the brakes.

fastwillie 696969 · 03-12-2012, 07:35 AM

i would check to see if the PV is off set

**dennislbrooks** · 03-12-2012, 07:42 AM

As OLDS says --- Check the length of the push rod between the booster and the master cylinder(assuming this is power set-up). If the rod is too long it wont allow the pressure to bleed back when you release the brakes.

You cannot preload the master cyclinder. You rod should be adjustable.

This happened to me and had to get a roolback to get it home.

Chevy Iron · 03-12-2012, 05:34 PM

Quote:

Originally Posted by fastwillie 696969

i would check to see if the PV is off set

Not sure what you mean by offset?

Chevy Iron · 03-12-2012, 05:36 PM

This is not a power booster setup but nevertheless, pedal rod was adjusted to be just snug to the master.

Chevy Iron · 03-12-2012, 05:37 PM

Would an adjustable proportioning valve work albeit reversed? Or is this not where the problem lies?

cdowns · 03-12-2012, 07:40 PM

Quote:

Originally Posted by Chevy Iron

This is not a power booster setup but nevertheless, pedal rod was adjusted to be just snug to the master.

there should be 1/8- 1/4 inch clearance to prevent drag

Chevy Iron · 03-12-2012, 08:40 PM

Quote:

Originally Posted by cdowns

there should be 1/8- 1/4 inch clearance to prevent drag

Could the difference of a 1/4" rod play make the fronts lock?
1/4" of play and the rod is out of the "socket".
I am curious though...I did not check the rod pressure or gap after bleeding, would it change?

cdowns · 03-13-2012, 07:35 AM

Quote:

Originally Posted by Chevy Iron

Could the difference of a 1/4" rod play make the fronts lock?
1/4" of play and the rod is out of the "socket".
I am curious though...I did not check the rod pressure or gap after bleeding, would it change?

the clearance is what is reccomended in the GM service manuals i have// they reccomend 1/16-1/4 actually

i believe it gives the plunger a chance to fully "spring" back and fully release the brakes

03-11-2012, 10:13 PM	#1
Chevy Iron Registered User Join Date: Sep 2011 Location: Libertyville, IL Posts: 28	Front Brakes LOCKED! Replaced the master and have the same issue. Third time on the brake pedal, the fronts are dragging and continue to do so until they are locked (all parts are new). Opening the line at the master cylinder releases all pressure on the calipers. Any advice? Thanks guys. __________________ Chevy Iron Fully customized 1968 C-10 Stovebolt 292, T-5 trans 3:73 posi Wife says it's a "midlife crisis".....I'm okay with that.

03-11-2012, 10:27 PM	#2
72freak Rottenwood Garage Member Join Date: May 2005 Location: Marietta, Georgia Posts: 4,321	Re: Front Brakes LOCKED! Any time I have locking brakes its the brake hoses collapsed. __________________ 2004 Chevrolet Suburban C1500 2001 Chevrolet 2500HD Crew 6.0 1999 Harley Davidson Electra Glide 1972 Chevrolet C-20 Custom Camper "Dump Truck" 1972 Chevrolet C-20 Suburban "Big Green" 1969 Chevrolet C-50 Wedge Hauler "Leonidis" 1966 C-10 2x4 short fleet 327 4 speed "Race Truck" 1952 Plymouth Cranbrook "Rican" (my grandfathers) 1931 Ford Model A Coupe "Black Beauty" 1930 Ford Model A truck "Club Cab" 4x4 Rottenwood Garage and Speed Shop.....where everything must be racy! *It's not just a hobby..It's a LIFESTYLE!!!* Thanks for nothing Barrett-Jackson You cant fix stupid or teach accountability! Time wasters, looky Lous and tire kickers are everywhere!

03-12-2012, 04:36 AM	#3
oldspowered67C10 Registered User Join Date: Jan 2006 Location: Cherry Valley,Ca Posts: 468	Re: Front Brakes LOCKED! Check the length of the push rod between the booster and the master cylinder(assuming this is power set-up). If the rod is too long it wont allow the pressure to bleed back when you release the brakes.

03-12-2012, 07:35 AM	#4
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	Re: Front Brakes LOCKED! i would check to see if the PV is off set __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

03-12-2012, 07:42 AM	#5
dennislbrooks Senior Member Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,798	Re: Front Brakes LOCKED! As OLDS says --- Check the length of the push rod between the booster and the master cylinder(assuming this is power set-up). If the rod is too long it wont allow the pressure to bleed back when you release the brakes. You cannot preload the master cyclinder. You rod should be adjustable. This happened to me and had to get a roolback to get it home.

03-12-2012, 05:36 PM	#7
Chevy Iron Registered User Join Date: Sep 2011 Location: Libertyville, IL Posts: 28	Re: Front Brakes LOCKED! This is not a power booster setup but nevertheless, pedal rod was adjusted to be just snug to the master. __________________ Chevy Iron Fully customized 1968 C-10 Stovebolt 292, T-5 trans 3:73 posi Wife says it's a "midlife crisis".....I'm okay with that.

03-12-2012, 05:37 PM	#8
Chevy Iron Registered User Join Date: Sep 2011 Location: Libertyville, IL Posts: 28	Re: Front Brakes LOCKED! Would an adjustable proportioning valve work albeit reversed? Or is this not where the problem lies? __________________ Chevy Iron Fully customized 1968 C-10 Stovebolt 292, T-5 trans 3:73 posi Wife says it's a "midlife crisis".....I'm okay with that.



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