Dazzi Posted September 3, 2012 Share Posted September 3, 2012 My gf's supra failed mot on reserve travel of the brakes. Bled the whole system and no air. We had the car on a lift and changed the master cylinder seals, bled the system and the pedal goes hard. Turned the car on and the brakes are great but as soon as we put the wheels back on and drop the car to the ground the pedal goes to the floor again! Is there possible trapped air in the master cylinder? We've done the technique from the manual and theres no air coming out. Cheers Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 3, 2012 Share Posted September 3, 2012 Have you tried using a vacuum bleeder? http://www.mkivsupra.net/vbb/showthread.php?274740-Long-brake-pedal-after-a-couple-of-hard-stops Post #9. Worked for me bigtime Quote Link to comment Share on other sites More sharing options...
Dazzi Posted September 4, 2012 Author Share Posted September 4, 2012 We've got a one man bleeder, pressure bleeder, vacuum bleeder and even manually bled it Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 4, 2012 Share Posted September 4, 2012 With the pressure bleeder, did it hold pressure? There may be a small leak somewhere in the system. Rusted brake line at the bottom of the bulkhead a la sticky thread in this section, or a diaphragm issue with the master cylinder vacuum booster, something obscure like that? You do say it's fine until you drop the car off the jacks? Can you be more specific about that behaviour? Quote Link to comment Share on other sites More sharing options...
Dazzi Posted September 5, 2012 Author Share Posted September 5, 2012 It held pressure yes. The car is on a lift so we can see everything. All the lines are bone dry, the car came with goodridge braided brake lines front and rear. All the calipers look good, no leaks what so ever. I did notice though when pressing the brakes while the car is off the pedal goes down and you can hear like a mooo noise like somethings losing pressure coming from the intake? Yea we bled the brakes 5 times now on the lift and the pedal goes rock solid. Start the car up and the brakes are great. As soon as we put the wheels on and drop the car to the floor the brakes go to the floor car on or off... it's so strange. My boss (mechanic for 20 years) has never heard of this before, neither any garage I've explained it to. Quote Link to comment Share on other sites More sharing options...
Dazzi Posted September 6, 2012 Author Share Posted September 6, 2012 A couple of us have come to the conclusion it may be a faulty braided brake hose because these are the only things moving when dropping the car. One of my mates mentioned this happened to him, turned out to be a crack in the nylon but it isn't causing a visable leak as its sealed... another things to look at! Quote Link to comment Share on other sites More sharing options...
Dazzi Posted September 14, 2012 Author Share Posted September 14, 2012 NOW FIXED! The car came with braided hoses originally and didn't look in too good shape so we went ahead and fitted some new ones. I took all the calipers off and noticed some of the sliders in the carriers twisted left and right but didn't go in or out. Spent 3 hours freeing up 3 sliders on 3 carriers. Im guessing when we put the wheels back on it was forcing the pistons in at an angle and not havin rubber hoses the braided lines can't expand causing pressure to go up the line and hold the master cylinder seals forward. Thats probably why there was a little abit of braking before the pedal was flat on the floor. I've done 100's of brake jobs and never experienced anything like this!! Crazy.. Quote Link to comment Share on other sites More sharing options...
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