Notices
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

front disk brakes locking up. help please.

Thread Tools
 
Search this Thread
 
Old Apr 17, 2008 | 07:54 PM
  #1  
scottddove's Avatar
scottddove
Thread Starter
|
More Turbo
20 Year Member
Joined: Aug 2005
Posts: 683
Likes: 6
From: North Georgia
front disk brakes locking up. help please.

its a 86 f-150 5.0 aod tranny. I was driving in some stop and go traffic for a hour or so and the truck started pulling to the left and right and then the right front tried to locked up for a few miles. I resorted to just using the emergency brakes for several miles and it freed up. I let it cool down and it went back to normal. What I want to know is what is the best way to correct this just replace everything from the steel lines to the hub or what do some of you mechanics recomend. I have been told the rubber brake lines can break down on the inside and pieces can act as a check valve and let fluid in the caliper but not let it out. what do you guys think.
 
Reply
Old Apr 17, 2008 | 08:03 PM
  #2  
Franklin2's Avatar
Franklin2
Moderator
25 Year Member
Photogenic
Community Builder
Community Influencer
Joined: Jan 2001
Posts: 56,980
Likes: 2,735
From: Virginia
Club FTE Gold Member
Find which one is sticking, and replace the caliper. 99% of the time it's rust in the caliper causing the piston to freeze up.
 
Reply
Old Apr 17, 2008 | 09:33 PM
  #3  
uncle.stosh's Avatar
uncle.stosh
Postmaster
Joined: Feb 2008
Posts: 2,658
Likes: 5
From: Out of here
If your truck is that old it's probably time to replace both any way. I would never just change one side and not the other.

I would also do the rubber brake lines too. Only bad thing is that once you touch one thing, everything else ends up being replaced too. It's difficult to get new rubber lines on without destroying the metal brake lines too.

Most of the time, I end up changing everything from the proportioning valve out to the pads. At least you will know that it is safe and you'll never have to worry about it again.

The parts aren't expensive but it takes a little time to do.
 
Reply
Old Apr 18, 2008 | 01:02 PM
  #4  
payday33's Avatar
payday33
Freshman User
Joined: Sep 2006
Posts: 40
Likes: 0
A leaking power brake booster will cause this also. I had this problem on a 1981 F100 several years ago. I could hear the leak, changed the booster and solved the problem.
 
Reply
Old Apr 18, 2008 | 02:03 PM
  #5  
85e150's Avatar
85e150
Super Moderator
20 Year Member
Community Builder
Liked
Community Favorite
Joined: Apr 2004
Posts: 34,481
Likes: 2,801
Club FTE Gold Member
You may have those quality plastic caliper pistons like my '85. A good rebuilt caliper will help.
 
Reply
Old Apr 18, 2008 | 07:22 PM
  #6  
kermmydog's Avatar
kermmydog
Post Fiend
Joined: Oct 2003
Posts: 9,176
Likes: 4
From: Western Central NV
If it was a power booster the brakes when you touch them would suck down. I'm in agreement with the calibers sticking, I also agree with changing the rubber hose brake lines. You should be able to buy either loaded or semi loaded calibers. I would change both sides if your going to mess with it.
 
Reply
Old Apr 18, 2008 | 09:49 PM
  #7  
scottddove's Avatar
scottddove
Thread Starter
|
More Turbo
20 Year Member
Joined: Aug 2005
Posts: 683
Likes: 6
From: North Georgia
I am going to go with new hoses,calipers, and pads. Have the rotors turned and see how that goes. I have done some looking around and have a question on the calipers. I see there are many diffrent ones from 20-60 dollars. Is it worth the extra money for the higher ones and what about the piston there is oem and steel ones. What is the best way to go on a truck I plan on keeping for a long time.
 
Reply
Old Apr 19, 2008 | 05:49 PM
  #8  
kermmydog's Avatar
kermmydog
Post Fiend
Joined: Oct 2003
Posts: 9,176
Likes: 4
From: Western Central NV
Smile

Originally Posted by scottddove
I am going to go with new hoses,calipers, and pads. Have the rotors turned and see how that goes. I have done some looking around and have a question on the calipers. I see there are many diffrent ones from 20-60 dollars. Is it worth the extra money for the higher ones and what about the piston there is oem and steel ones. What is the best way to go on a truck I plan on keeping for a long time.
I would go with the steel myself. I think someone on here suggested that the OEM could be plastic.
Scott, if it was me I would go to a NAPA & ask for a loaded replacement with steel pistons. What I do if there are different ones I ask the parts guys to give a GOOD QUALITY UNIT. You don't need a PREMIUM but you don't want a cheap one either. "LOADED" MEANS THEY COME WITH PADS. Ready to hook up the brake lines bleed & go.
Craig
 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

 Joe Kucinski
story-1

2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

 Brett Foote
story-2

Top 10 Ford Truck Tragedies

 Joe Kucinski
story-3

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

 Brett Foote
story-4

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

 Michael S. Palmer
story-5

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

 Verdad Gallardo
story-6

10 Best Ford Truck Engines We Miss the Most!

 Joe Kucinski
story-7

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

 Brett Foote
story-8

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

 Michael S. Palmer
story-9

10 Most Surprising 2026 Ford Truck Features!

 Joe Kucinski
Old Apr 20, 2008 | 12:59 PM
  #9  
payday33's Avatar
payday33
Freshman User
Joined: Sep 2006
Posts: 40
Likes: 0
My pedal didn't go down. I replaced the pistons and the problem was still there. Replacing the power booster cleared the problem. I still drive the truck occiasionally and have had no more problems with it after about 10 years.

All I know is what I have read in a Chiltons 1975 Auto Repair Manual. Power brakes are activated by by depressing the brake pedal which closes off vacuum and allows atmospheric pressure to enter on one side of the diaphragm causing the master cylinder pistons to move and apply the brakes.

If there is a bad vacuum leak, the brakes will be applied a small amount. it may not be enough to even be noticed but there may enough friction to cause the brakes to heat up and seize. It would have the same result as riding the brakes. "Been there and done that".
 
Reply
Old Apr 20, 2008 | 02:02 PM
  #10  
Franklin2's Avatar
Franklin2
Moderator
25 Year Member
Photogenic
Community Builder
Community Influencer
Joined: Jan 2001
Posts: 56,980
Likes: 2,735
From: Virginia
Club FTE Gold Member
Originally Posted by payday33
My pedal didn't go down. I replaced the pistons and the problem was still there. Replacing the power booster cleared the problem. I still drive the truck occiasionally and have had no more problems with it after about 10 years.

All I know is what I have read in a Chiltons 1975 Auto Repair Manual. Power brakes are activated by by depressing the brake pedal which closes off vacuum and allows atmospheric pressure to enter on one side of the diaphragm causing the master cylinder pistons to move and apply the brakes.

If there is a bad vacuum leak, the brakes will be applied a small amount. it may not be enough to even be noticed but there may enough friction to cause the brakes to heat up and seize. It would have the same result as riding the brakes. "Been there and done that".
Changing the booster probably did fix your problem, but what really was wrong was the length adjustment of the rod between the booster and the master cylinder. If it's set too long, it will cover up the compensation ports in the master cylinder, which blocks the fluid from being able to come back up into the master cylinder as you are driving down the road. Then what happens is as the fluid gets warm, it expands, and if it can't go back up into the master cylinder, it will start applying the brakes.
 
Reply
Old Apr 21, 2008 | 07:48 AM
  #11  
payday33's Avatar
payday33
Freshman User
Joined: Sep 2006
Posts: 40
Likes: 0
So, Who or what changed the push rod length?. The booster was leaking. I could hear the leak. There was a loss of vacuum in the booster. A loss of vacuum causes power brakes to activate.
 
Reply




All times are GMT -5. The time now is 11:44 AM.

story-0
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-1
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-2
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE
story-3
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-4
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-5
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-6
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-7
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE
story-8
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Slideshow: Everything You Need to Know about the 2027 Super Duty Carhartt Package!

By Michael S. Palmer | 2026-05-07 17:51:06


VIEW MORE
story-9
10 Most Surprising 2026 Ford Truck Features!

Slideshow: 10 most surprising Ford truck options/features in 2026.

By Joe Kucinski | 2026-05-05 11:17:22


VIEW MORE