Front Brakes Locked Up
08-09-2016, 04:11 PM
#1
Cruising
Thread Starter
Front Brakes Locked Up
I need a little help on 1989 corvette that I'm have with my my brakes. My front brakes are locked up. No warning ABS and brake lights on. I did a complete brake job on my C4. Changed the power booster, master cylinder, brake shoes, calipers, rotors and brake hoses. I checked the alignment with the master cylinder and the power booster is correctly adjusted.
I'm in the process of cleaning the wheel speed sensors, bleeding the brake brake relay and abs valve relay.
When I turn the key just below the start position the ABS and Brake warning display and go off. When I start my corvette it displays the brake and abs warning light and it goes out.
Appreciate your assistance resolving my corvette problem.
I'm in the process of cleaning the wheel speed sensors, bleeding the brake brake relay and abs valve relay.
When I turn the key just below the start position the ABS and Brake warning display and go off. When I start my corvette it displays the brake and abs warning light and it goes out.
Appreciate your assistance resolving my corvette problem.
08-09-2016, 04:15 PM
#2
Team Owner
Pro Mechanic
I need a little help on 1989 corvette that I'm have with my my brakes. My front brakes are locked up. No warning ABS and brake lights on. I did a complete brake job on my C4. Changed the power booster, master cylinder, brake shoes, calipers, rotors and brake hoses. I checked the alignment with the master cylinder and the power booster is correctly adjusted.
I'm in the process of cleaning the wheel speed sensors, bleeding the brake brake relay and abs valve relay.
When I turn the key just below the start position the ABS and Brake warning display and go off. When I start my corvette it displays the brake and abs warning light and it goes out.
Appreciate your assistance resolving my corvette problem.
I'm in the process of cleaning the wheel speed sensors, bleeding the brake brake relay and abs valve relay.
When I turn the key just below the start position the ABS and Brake warning display and go off. When I start my corvette it displays the brake and abs warning light and it goes out.
Appreciate your assistance resolving my corvette problem.
.
Last edited by Tom400CFI; 08-09-2016 at 04:16 PM.
08-10-2016, 03:20 PM
#4
Safety Car
Since you replaced both the booster and the master cylinder, did you adjust the pushrod between those two items? If the pushrod is too long, your brakes will drag or lock up.
It's an easy test:
1. Open hood and remove cap(s) from master.
2. Open front door and stand beside car with right foot on brake pedal (engine off).
3. Gently press on brake pedal while watching the fluid in the reservoir.
4. You should see a "jet" of brake fluid disturb the surface of the fluid.
There is a port in the bottom of the reservoir that needs to be open when your foot is off the brake pedal, to relieve any pressure in the master cylinder. If the pushrod is too long, this port won't be open. If the pushrod is too short, you'll still see the "jet" of fluid, but the pedal will move farther than necessary, and the pedal will be too close to the floor at full travel.
To adjust the pushrod, separate the master from the booster. (No need to remove the brake lines from the master.) Gently pull the pushrod out of the booster. Grab the pushrod with pliers. Turn the adjustment screw in the end of the pushrod.
It's an easy test:
1. Open hood and remove cap(s) from master.
2. Open front door and stand beside car with right foot on brake pedal (engine off).
3. Gently press on brake pedal while watching the fluid in the reservoir.
4. You should see a "jet" of brake fluid disturb the surface of the fluid.
There is a port in the bottom of the reservoir that needs to be open when your foot is off the brake pedal, to relieve any pressure in the master cylinder. If the pushrod is too long, this port won't be open. If the pushrod is too short, you'll still see the "jet" of fluid, but the pedal will move farther than necessary, and the pedal will be too close to the floor at full travel.
To adjust the pushrod, separate the master from the booster. (No need to remove the brake lines from the master.) Gently pull the pushrod out of the booster. Grab the pushrod with pliers. Turn the adjustment screw in the end of the pushrod.
The following users liked this post:
Klondike (08-11-2016)
08-11-2016, 01:40 PM
#5
Race Director
Since you replaced both the booster and the master cylinder, did you adjust the pushrod between those two items? If the pushrod is too long, your brakes will drag or lock up.
It's an easy test:
1. Open hood and remove cap(s) from master.
2. Open front door and stand beside car with right foot on brake pedal (engine off).
3. Gently press on brake pedal while watching the fluid in the reservoir.
4. You should see a "jet" of brake fluid disturb the surface of the fluid.
There is a port in the bottom of the reservoir that needs to be open when your foot is off the brake pedal, to relieve any pressure in the master cylinder. If the pushrod is too long, this port won't be open. If the pushrod is too short, you'll still see the "jet" of fluid, but the pedal will move farther than necessary, and the pedal will be too close to the floor at full travel.
To adjust the pushrod, separate the master from the booster. (No need to remove the brake lines from the master.) Gently pull the pushrod out of the booster. Grab the pushrod with pliers. Turn the adjustment screw in the end of the pushrod.
It's an easy test:
1. Open hood and remove cap(s) from master.
2. Open front door and stand beside car with right foot on brake pedal (engine off).
3. Gently press on brake pedal while watching the fluid in the reservoir.
4. You should see a "jet" of brake fluid disturb the surface of the fluid.
There is a port in the bottom of the reservoir that needs to be open when your foot is off the brake pedal, to relieve any pressure in the master cylinder. If the pushrod is too long, this port won't be open. If the pushrod is too short, you'll still see the "jet" of fluid, but the pedal will move farther than necessary, and the pedal will be too close to the floor at full travel.
To adjust the pushrod, separate the master from the booster. (No need to remove the brake lines from the master.) Gently pull the pushrod out of the booster. Grab the pushrod with pliers. Turn the adjustment screw in the end of the pushrod.
08-11-2016, 06:25 PM
#6
Cruising
Thread Starter
Thank you. It's a hydraulic problem. It must be the ABS. I do not understand why the ABS and Brake warning is not on. Appreciate you reply. Any way to check the ABS is bad？
The following users liked this post:
RUSHTK (04-04-2022)
08-11-2016, 06:42 PM
#7
Get it out on some gravel and work them then rebleed. Sounds like you let air in by letting it sit while apart.
08-11-2016, 07:28 PM
#8
Team Owner
Pro Mechanic
Cycle the ABS a bunch...then re-bleed.
08-12-2016, 08:47 PM
#9
Cruising
Thread Starter
04-04-2022, 05:28 PM
#10
Intermediate
Next step for hydraulic
What were you able to find out? Mine is doing the exact thing. I just went and released the pressure and all is well. This stinks!
