Sticky brakes
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Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
Likes: 1
From: Iowa
Sticky brakes
The brakes on my '78 Supercab stick. When I press the pedal down, it stays there, and the brakes stay activated. The pedal won't return unless I pull it up. Is this a problem with the wheel cylinders or the calipers?
Thread Starter
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Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
Likes: 1
From: Iowa
Sticky brakes
Yeah, it doesn't get driven much. No muffler, no mileage, no manners... :-) I live in Iowa. Humidity can go from 30% to 110% in an hour and stay that way for a month.
Thread Starter
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Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
Likes: 1
From: Iowa
Sticky brakes
My brakes act as if there's a one way valve in the line. They'll stop the truck, but the brake pedal doesn't release untill I pry it from the floor with my foot.
I installed new calipers tonight, but they didn't fix the problem. Looks like I'll tear apart the wheel cylinders next...
I installed new calipers tonight, but they didn't fix the problem. Looks like I'll tear apart the wheel cylinders next...
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Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
Sticky brakes
The brake pedal is independant of the master cylinder. If it is sticking down, it has to be in the pedal pivot or there is so much crapola in the activating rod that is is sticking in the master cylinder. What I am trying to say is that even if the hydralics are pressurized the pedal will always return... the rod just sticks into the cup in the master cylinder, it is not "bi-directionally coupled"....roger?
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Posting Guru
Joined: Aug 2002
Posts: 1,214
Likes: 2
From: Minneapolis, MN
Sticky brakes
I've had the lever action pivot mechanism between the firewall and the booster freeze up. Same symptoms. After disassembly, cleaning (rusty pivot bushing), lube and reassembly it works great now.
Logistics Pro
Joined: May 2003
Posts: 4,238
Likes: 21
From: Northern Illinois
Sticky brakes
What I am trying to say is that even if the hydralics are pressurized the pedal will always return... the rod just sticks into the cup in the master cylinder, it is not "bi-directionally coupled"....roger?
if the master cylinder has locked in a brake on position then i could see it happening. the master cylinder has a spring in it to return to a neutral position, if it is locked in a brake applied condition that will help to keep the pedal from returning to the "off" position
for his particular problem of the pedal not returning i agree it has probably got crud built up around the rod, but if his brakes are staying on all the time untill he has pulled up that pedal then i would look more at the master cylinder
390fe does this truck have power assisted brakes? do the brakes stay locked up untill you pry the pedal back up and then start to slowly release? how hard is it to pry the pedal back to normal condition?
New User
Joined: Jan 2008
Posts: 0
Likes: 24
Sticky brakes
I had a pedal that stuck to the floor before.
The Cause :
Rear wheel cylinders staying in the on position.
Even the return springs couldn't suck the pistons back in.
This happens on vehicles that sit in humid conditions for months.
Maybe it isn't the case here, but it was with mine.
The Cause :
Rear wheel cylinders staying in the on position.
Even the return springs couldn't suck the pistons back in.
This happens on vehicles that sit in humid conditions for months.
Maybe it isn't the case here, but it was with mine.
Thread Starter
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Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
Likes: 1
From: Iowa
Sticky brakes
Ranger429 wrote:
390fe does this truck have power assisted brakes? do the brakes stay locked up untill you pry the pedal back up and then start to slowly release? how hard is it to pry the pedal back to normal condition?
This truck does have power assist brakes. As soon as I pull the brake pedal off the floor the brakes release. It pulls fairly easily. I'm inclined to agree that the spring inside the mc probably is at fault.
I'm also going to tear apart the rear brakes to make sure everything back there is working properly. As Dennis notes, this truck does sit around a lot...
390fe does this truck have power assisted brakes? do the brakes stay locked up untill you pry the pedal back up and then start to slowly release? how hard is it to pry the pedal back to normal condition?
This truck does have power assist brakes. As soon as I pull the brake pedal off the floor the brakes release. It pulls fairly easily. I'm inclined to agree that the spring inside the mc probably is at fault.
I'm also going to tear apart the rear brakes to make sure everything back there is working properly. As Dennis notes, this truck does sit around a lot...
Logistics Pro
Joined: May 2003
Posts: 4,238
Likes: 21
From: Northern Illinois
Sticky brakes
the brake pedal is hooked to the booster with a rod that is hooked at both ends (not free floating) and the booster is conected to the master with a push rod that is of free floating. check your vacum at the booster, probably not the problem. it could be something as simple as the rods a bit rusty from pedal to booster, does it feel like the power assist is working? i think there is a spring inside the power booster also which may have some kind of effect on your problem here, i never tore apart one tho so not sure
if the brakes are not hanging up i would think the master is ok, pulling the pedal back up by hand more than likely will not return the master cylinder to neutral position if it was hanging up
if the brakes are not hanging up i would think the master is ok, pulling the pedal back up by hand more than likely will not return the master cylinder to neutral position if it was hanging up
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
Sticky brakes
????
I am not sure what you are disagreeing with. I may be recollecting incorrectly but I thought that there is a pedal return spring, perhaps there is not. Anyway, I think we all agree that brakes sticking (master and/or wheel cylinders) are a separate issue from the pedal sticking. No?
I am not sure what you are disagreeing with. I may be recollecting incorrectly but I thought that there is a pedal return spring, perhaps there is not. Anyway, I think we all agree that brakes sticking (master and/or wheel cylinders) are a separate issue from the pedal sticking. No?
Logistics Pro
Joined: May 2003
Posts: 4,238
Likes: 21
From: Northern Illinois
Sticky brakes
no there is no pedal return spring that i am aware of? there is a very heavy duty spring inside the master cylinder tho, if the master hangs up it would be part of a problem of a sticky pedal. i don't think altho others do that if the calipers and wheel cylinders are hanging up it will cause a sticky pedal