Brakes locking up
Thread Starter
|
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Brakes locking up
Having an issue with my '84 Bronco.
As I press the pedal, the brakes go from soft to full lock, making the tires skid and burn rubber.
I know it's not the tires, since I just took them off my other Bronco (which has had the brakes completely redone within the last several years), and they're great tires that stop well even in snow.
What would cause brakes to lock so easily?
As I press the pedal, the brakes go from soft to full lock, making the tires skid and burn rubber.
I know it's not the tires, since I just took them off my other Bronco (which has had the brakes completely redone within the last several years), and they're great tires that stop well even in snow.
What would cause brakes to lock so easily?
Thread Starter
|
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
I've only owned it a few months, and I intend to just give it new brakes sometime next year. But I've driven vehicles with worn brakes before and have never experienced these symptoms.
Its a gentle brake for about the first 50 - 70% of the brake travel (not really enough to stop it effectively either), and then suddenly full lock. I think it may just be the rears that are locking, but I'm not sure.
I admit that I didn't inspect the front pads while I had the tires off. I should have. However, I did look at the rotors and they looked fine.
Its a gentle brake for about the first 50 - 70% of the brake travel (not really enough to stop it effectively either), and then suddenly full lock. I think it may just be the rears that are locking, but I'm not sure.
I admit that I didn't inspect the front pads while I had the tires off. I should have. However, I did look at the rotors and they looked fine.
Elder User
Joined: Sep 2010
Posts: 667
Likes: 0
From: Small acerage in Nebraska
sounds like maybe a wheel cylinder or more is hanging up, or is "sticky", find a clear gravel road and apply brakes to tell which wheel(s) are locking up. The problem might resolve itself with some use.
Freshman User
Joined: Oct 2010
Posts: 43
Likes: 0
From: oh
I've only owned it a few months, and I intend to just give it new brakes sometime next year. But I've driven vehicles with worn brakes before and have never experienced these symptoms.
Its a gentle brake for about the first 50 - 70% of the brake travel (not really enough to stop it effectively either), and then suddenly full lock. I think it may just be the rears that are locking, but I'm not sure.
I admit that I didn't inspect the front pads while I had the tires off. I should have. However, I did look at the rotors and they looked fine.
Its a gentle brake for about the first 50 - 70% of the brake travel (not really enough to stop it effectively either), and then suddenly full lock. I think it may just be the rears that are locking, but I'm not sure.
I admit that I didn't inspect the front pads while I had the tires off. I should have. However, I did look at the rotors and they looked fine.
Thread Starter
|
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Thanks for the advice. It's probably just needing new brakes all around. I didn't know if it was something I could adjust at the moment to clear the issue up until I could get a full brake rebuild.
I haven't diagnosed which tire/axle it is yet, but I am thinking it is the driver side rear, since when it locks, the Bronco likes to make a pretty good pull to the left. Get a lot of frightened looks from people who hear the tire squealing sound too....
I haven't diagnosed which tire/axle it is yet, but I am thinking it is the driver side rear, since when it locks, the Bronco likes to make a pretty good pull to the left. Get a lot of frightened looks from people who hear the tire squealing sound too....
Trending Topics
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
I have this issue once in a while in particularly humid weather if I set the parking brake. Ends up being flash rust in the drum and the brake shoes grab hard until they wear away the thin layer of flash rust. However, in my example, it usually only happens with the first few applications of the brake then it clears up.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Thread Starter
|
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Turns out the master cylinder was bad. It was applying pressure on the fronts, but not the rears until the pedal was almost all the way down. Then, the rears would go from 0 to full braking.
A new master cylinder, bench bleed, and then a full brake system bleed fixed the issue and the brakes are as good as new.
A new master cylinder, bench bleed, and then a full brake system bleed fixed the issue and the brakes are as good as new.
Thread Starter
|
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Lol, opened the hood and saw that since I had last looked, the master cylinder had emptied all of it's brake fluid contents for the rear brakes down the front of the power booster. Needless to say, the booster no longer has any paint on it.
Cargo Master
Joined: May 2004
Posts: 3,007
Likes: 5
My 1990 Bronco has a system that turns the brake light on and the RABS light if the brake fluid gets too low. So a couple of times now I've had to refill the master cylinder and I'm chasing down where it's leaking from, it's a very slow leak. I'm starting at the brakes and moving toward the master cylinder, but I'm lazy so it's taking awhile and the brake fluid doesn't go down really fast, so it's not a big deal, but I was looking for caps to put on the master cylinder to block off the lines to check the master cylinder for leaks.
Yours was leaking where the master cylinder attaches to the brake booster?
Yours was leaking where the master cylinder attaches to the brake booster?
Thread Starter
|
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
This was a pretty drastic leak. I wasn't losing anything until I noticed the weird brake lockup. Then, popped the hood and the whole front of the booster was soaking wet with brake fluid and the MC was empty. The paint on the booster had bubbled up and peeled off like latex.
Yeah, it was leaking from where the master cylinder bolts to the booster.
$15 for a new master cylinder and an hour of my time was all it took.
It was the old style though, not sure how the work would be different for a 1990.
Yeah, it was leaking from where the master cylinder bolts to the booster.
$15 for a new master cylinder and an hour of my time was all it took.
It was the old style though, not sure how the work would be different for a 1990.
Thread
Thread Starter
Forum
Replies
Last Post
95'F150
1987 - 1996 F150 & Larger F-Series Trucks
18
Feb 16, 2021 06:50 AM
wolfrace
1999 - 2003 7.3L Power Stroke Diesel
6
Apr 27, 2010 11:44 PM
