GTB Brakes Air Bubbles Apearing

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integrated12345

integrated12345

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Hi Guys, i tried posting this in another thread but was late to the party and got no response so i thought i'd post a new thread:

I have just setup GTB Brakes on my 1/4 Sprintcar, no matter what way i try to bleed them as soon as i brake and hit the throttle air appears from the master cylinder hose connection, lots of small bubbles, i've tried bleeding from the caliper towards the master cylinder and vice versus, after a few minutes of track time the brakes just don't work from too much air, the system is new and everything is tightened correctly, no leaks too. I much prefer the real cars brake bleed nipple with the hose nipple so you can simply tighten the bleed nipple with the hose still connected instead of quickly trying to put a block off bolt back in while pushing the fluid threw slowly at the same time. Have any of you figured out a way to remove the air from the master cylinder?
 

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Sounds like the master cylinder is the one introducing the air. I wonder if the seals took a crap inside the piston for it. Have you taken the master apart yet?
 
lol mate,i've been there, done that with GTB brakesand yes they are a proper pain,to bleed,
they're known for beiing bad for bleeding as well,,
but the way ended up doingit was, bleed from caliper to mastr, make sure the bleed hole in the master is the absolute highest point,
ie; make sure theres no tilt at all with the master cos air gets trapped in the corners of the resevoir,
then keep bleeding em, bleed, fit plug bolt and work the master, rebleed as air appears, then repeat over and over untill no air cones through,
they will work well in the end, but you're gonna have to bleed em regularly, maybe even after every use if you use em a lot,
but should be quick bleeds once you get almost all the air out,
another thing i did was take the master apart and soak the umbrella seal in fluid overnight, reassemble and bleed from there,
i used good quality dot4 fluid as well
good luck mate (y)
 
spents said:
lol mate,i've been there, done that with GTB brakesand yes they are a proper pain,to bleed,
they're known for beiing bad for bleeding as well,,
but the way ended up doingit was, bleed from caliper to mastr, make sure the bleed hole in the master is the absolute highest point,
ie; make sure theres no tilt at all with the master cos air gets trapped in the corners of the resevoir,
then keep bleeding em, bleed, fit plug bolt and work the master, rebleed as air appears, then repeat over and over untill no air cones through,
they will work well in the end, but you're gonna have to bleed em regularly, maybe even after every use if you use em a lot,
but should be quick bleeds once you get almost all the air out,
another thing i did was take the master apart and soak the umbrella seal in fluid overnight, reassemble and bleed from there,
i used good quality dot4 fluid as well
good luck mate (y)
Click to expand...
Thanks for the info, I'm currently using Shimano mineral oil the same that's in my Scot mountain bike, I'll maybe switch to Dot4 soon
 
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