Updated:: Magical Disappearing Brakes - 92 Mustang -- FIXED!!!
OK, For all of you that are new to this thread, I am updating this post with a list of everything that has been tried, tested, and done to this vehicle to help fix my problem, and to help catch you up to speed since this post is so long. The original Question is below this update in BOLD print. Any help you can throw my way is much appreciated.
Round1
Installed used V8 front disk/rear drum brakes from 1987 GT
Installed new hard and soft lines
Installed used manual pedals
Kept 4 cylinder master proportioning valve and booster
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 2
Changed master cylinder to remanufactured 4 cylinder unit
Bench bled master cylinder using tube into reservoir method
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 3
Changed master cylinder to new V8 unit
Bench bled master cylinder using tube into reservoir method
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 4
Pull master cylinder
Gravity bleed master cylinder
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 5
Vacuum tested booster, failed test.
Changed booster to remanufactured V8 booster
Still NO pedal AT ALL!
Round 6
Transported to friends shop
Check for leaks at all lines, rear wheel cylinders, front calipers
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 7
Remove proportioning valve
Tear down and clean
Re-install proportioning valve and cross threaded right front line fitting
Obtain replacement used proportioning valve
Tear down and clean
Re-install proportioning valve
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 8
Removed master cylinder, removed brake booster pushrod, lengthened to 6 3/8” to match a factory pushrod obtained at the salvage yard
Only change to pedal was increased step between front and rear circuits
Check adjustment of rear brakes
Change master cylinder to another new AP manufactured V8 unit
Bench bled master cylinder using tube into reservoir method
Install on vehicle
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Bleed all lines at the junction, working from the furthest point forward up to the proportioning valve
Bleed system manually at each corner RR, LF, LR, RF Ford service manual method, NO pedal AT ALL!
Round 9
Removed master cylinder
Bench bled master cylinder using "capped ports" method recommended by Maximum Motorsports Tech line
Piston will not move all in bore of master cylinder indicating no air
Re-installed on vehicle
Bleed system manually at each corner RR, LF, LR, RF Ford service manual method, NO pedal AT ALL!
Round 10
Change master cylinder to new O'Reilly's unit
Installed as is with no bench bleeding
Pressure bleed system
FIRST SIGNS OF PEDAL
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 11
Continue to pressure bleed, run through 2 quarts of new fluid
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 12
With the pressure bleeder installed and operating, pedal holds pressure and feels fine
This led us to believe that there was still air in the system
Continue to pressure bleed
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 13
Decided to obtain a used booster and master cylinder from a U-Pull-It yard
Found a 4 cylinder one, tried it in the car at the salvage yard and it had pedal
Install used booster and master
Pressure bleed system
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 14
Remove master cylinder from booster, but kept lines installed, lifted above firewall to bring it above the rear and right front wheel lines on firewall
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 15
Started blocking off circuits on the vehicle to eliminate the possibility of trapped air
Starting at the rear junction on the firewall
Pedal is the same
Clamp off right front circuit at soft line to caliper with a line clamp
First stroke is off of floor 1/4 throw
Second and every stroke after words is 1/2 throw
Let it sit for a minute and starts over again
Clamp off left front and right front at soft line to caliper with a line clamp
First stroke is off of floor 1/4 throw
Second and every stroke after words is 1/2 throw
Let it sit for a minute and starts over again
Round 16
Block off right front circuit at prop valve
First stroke is off of floor 1/4 throw
Second and every stroke after words is 1/2 throw
Let it sit for a minute and starts over again
Round 17
Block off left front at master cylinder (comes directly from master cylinder)
Dead heads master cylinder and will not allow the pedal to be depressed at all
Round 18
Removed right front brake line at prop valve
Inserted prop valve end of line into bottle of brake fluid and vacuum bled line at caliper
Round 18
Decided to try new front calipers even though we didn't see any leaks around the piston seals and bleeder, line, etc.
Installed remanufactured calipers
Pressure bled system
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 19
Doused car in fuel
Lit match
Couldn't muster up the nuts to watch it burn just yet
Ok, I've been dealing with this problem for a LONG time now and I am now reachin out for help from others. Here's the deal::
1992 4cyl Mustang converted to 302....
1987 GT Rear Axle (rebuilt drums and new shoes)
1987 GT Front Brakes (factory calipers w/ new pads; factory size rotors and calipers)
BRAND NEW Brake Hard lines; all 4 corners
BRAND NEW Front and Rear Soft lines
BRAND NEW V8 Brake Booster
BRAND NEW V8 Master Cylinder
Factory 4cyl. Proportioning (aka Combination) Valve
I have bled the brakes at all four corners and I have bench bled the master cylinder until absolutely NO air comes out. There are NO Leaks at any of the fittings. All the hard brake lines have been verified to be connected in the right places on both the Master Cylinder and the Prop Valve. There are no vacuum leaks, and the Vacuum at idle is 14in. HG (or whatever vacuum is measured at). When the car is off, I have good pedal feel and pressure, but as soon as I start the car, I lose ALL pedal... it ''Magically disappears".
- With the car off and with the brake pedal to the floor, you can turn all four tires by hand.
- With the car running and with the brake pedal to the floor, you can turn all four tires by hand.
- If you put the car in gear and then apply the brakes to the floor (which will kill the car), you CANNOT turn the tires by hand at ALL.... Locked up tighter than a bull's A** at fly time.
As stated above, Just about EVERY part in this system that has to do with brake pressure is new.... The only part that has yet to be replaced is the Proportioning Valve and it is the factory 4cyl piece. I'm planning on pulling the Prop valve apart tomorrow and cleaning/checking functionality of the valve.
Basically my question is::
Has anybody had this problem? If you have, what ended up being the problem? If you haven't had this problem, do you have ANY idea on what could be causing this?
Please Help
--Ryan
OK, For all of you that are new to this thread, I am updating this post with a list of everything that has been tried, tested, and done to this vehicle to help fix my problem, and to help catch you up to speed since this post is so long. The original Question is below this update in BOLD print. Any help you can throw my way is much appreciated.
Round1
Installed used V8 front disk/rear drum brakes from 1987 GT
Installed new hard and soft lines
Installed used manual pedals
Kept 4 cylinder master proportioning valve and booster
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 2
Changed master cylinder to remanufactured 4 cylinder unit
Bench bled master cylinder using tube into reservoir method
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 3
Changed master cylinder to new V8 unit
Bench bled master cylinder using tube into reservoir method
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 4
Pull master cylinder
Gravity bleed master cylinder
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 5
Vacuum tested booster, failed test.
Changed booster to remanufactured V8 booster
Still NO pedal AT ALL!
Round 6
Transported to friends shop
Check for leaks at all lines, rear wheel cylinders, front calipers
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 7
Remove proportioning valve
Tear down and clean
Re-install proportioning valve and cross threaded right front line fitting
Obtain replacement used proportioning valve
Tear down and clean
Re-install proportioning valve
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Round 8
Removed master cylinder, removed brake booster pushrod, lengthened to 6 3/8” to match a factory pushrod obtained at the salvage yard
Only change to pedal was increased step between front and rear circuits
Check adjustment of rear brakes
Change master cylinder to another new AP manufactured V8 unit
Bench bled master cylinder using tube into reservoir method
Install on vehicle
Bleed system manually at each corner RR, LR, RF, LF method, NO pedal AT ALL!
Bleed all lines at the junction, working from the furthest point forward up to the proportioning valve
Bleed system manually at each corner RR, LF, LR, RF Ford service manual method, NO pedal AT ALL!
Round 9
Removed master cylinder
Bench bled master cylinder using "capped ports" method recommended by Maximum Motorsports Tech line
Piston will not move all in bore of master cylinder indicating no air
Re-installed on vehicle
Bleed system manually at each corner RR, LF, LR, RF Ford service manual method, NO pedal AT ALL!
Round 10
Change master cylinder to new O'Reilly's unit
Installed as is with no bench bleeding
Pressure bleed system
FIRST SIGNS OF PEDAL
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 11
Continue to pressure bleed, run through 2 quarts of new fluid
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 12
With the pressure bleeder installed and operating, pedal holds pressure and feels fine
This led us to believe that there was still air in the system
Continue to pressure bleed
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 13
Decided to obtain a used booster and master cylinder from a U-Pull-It yard
Found a 4 cylinder one, tried it in the car at the salvage yard and it had pedal
Install used booster and master
Pressure bleed system
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 14
Remove master cylinder from booster, but kept lines installed, lifted above firewall to bring it above the rear and right front wheel lines on firewall
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 15
Started blocking off circuits on the vehicle to eliminate the possibility of trapped air
Starting at the rear junction on the firewall
Pedal is the same
Clamp off right front circuit at soft line to caliper with a line clamp
First stroke is off of floor 1/4 throw
Second and every stroke after words is 1/2 throw
Let it sit for a minute and starts over again
Clamp off left front and right front at soft line to caliper with a line clamp
First stroke is off of floor 1/4 throw
Second and every stroke after words is 1/2 throw
Let it sit for a minute and starts over again
Round 16
Block off right front circuit at prop valve
First stroke is off of floor 1/4 throw
Second and every stroke after words is 1/2 throw
Let it sit for a minute and starts over again
Round 17
Block off left front at master cylinder (comes directly from master cylinder)
Dead heads master cylinder and will not allow the pedal to be depressed at all
Round 18
Removed right front brake line at prop valve
Inserted prop valve end of line into bottle of brake fluid and vacuum bled line at caliper
Round 18
Decided to try new front calipers even though we didn't see any leaks around the piston seals and bleeder, line, etc.
Installed remanufactured calipers
Pressure bled system
First stroke goes completely to floor
Second stroke is off of floor 1/4 throw
Third and every stroke after words is 1/2 throw
Let it sit for a minute and first stroke goes to the floor again, etc.
Round 19
Doused car in fuel
Lit match
Couldn't muster up the nuts to watch it burn just yet
Ok, I've been dealing with this problem for a LONG time now and I am now reachin out for help from others. Here's the deal::
1992 4cyl Mustang converted to 302....
1987 GT Rear Axle (rebuilt drums and new shoes)
1987 GT Front Brakes (factory calipers w/ new pads; factory size rotors and calipers)
BRAND NEW Brake Hard lines; all 4 corners
BRAND NEW Front and Rear Soft lines
BRAND NEW V8 Brake Booster
BRAND NEW V8 Master Cylinder
Factory 4cyl. Proportioning (aka Combination) Valve
I have bled the brakes at all four corners and I have bench bled the master cylinder until absolutely NO air comes out. There are NO Leaks at any of the fittings. All the hard brake lines have been verified to be connected in the right places on both the Master Cylinder and the Prop Valve. There are no vacuum leaks, and the Vacuum at idle is 14in. HG (or whatever vacuum is measured at). When the car is off, I have good pedal feel and pressure, but as soon as I start the car, I lose ALL pedal... it ''Magically disappears".
- With the car off and with the brake pedal to the floor, you can turn all four tires by hand.
- With the car running and with the brake pedal to the floor, you can turn all four tires by hand.
- If you put the car in gear and then apply the brakes to the floor (which will kill the car), you CANNOT turn the tires by hand at ALL.... Locked up tighter than a bull's A** at fly time.
As stated above, Just about EVERY part in this system that has to do with brake pressure is new.... The only part that has yet to be replaced is the Proportioning Valve and it is the factory 4cyl piece. I'm planning on pulling the Prop valve apart tomorrow and cleaning/checking functionality of the valve.
Basically my question is::
Has anybody had this problem? If you have, what ended up being the problem? If you haven't had this problem, do you have ANY idea on what could be causing this?
Please Help
--Ryan
probably with the booster? i just wish i knew more, or was able to be there under the hood to lend a helping hand. unless i see it first hand, i really dont know where to start, and i think i misunderstood something too...
