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POS 85 supra, 03 Impreza shitbox edition
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Got a bit of a weird one. So I got my 85 supra, removed and rebuilt all 4 of my calipers, since you cant get them new or remanufactured anymore (new seals, dust boots, polished the pistons, re-greased the sliders, rust delete, red caliper paint the works). Bled the master cylinder too albeit still on the car but bled none the less. I re-installed the lines and then bled all 4 brakes again and the pedal still hits the floor before actually stopping the car. the last quarter of pedal travel is the part that actually does anything. I'm wondering if i missed a step, did something wrong or its just a faulty part.

here's a detailed list of things that might contribute to the issue; Before I took the calipers off the pedal was rock hard and braking was pretty good but after rebuilding and putting them back on i just cant seem to get the pressure back. I checked all 4 calipers for leaks so I doubt that's the problem. I had a similar issue 2 years ago and took the car to a shop and they ended up replacing my brake hoses, when i got it back the car braked like it was new, solid pedal feel and even braking, and hasn't given me any trouble up until now. One thing that may be an issue was that i had the car up on jack stands for a week or two while I rebuilt the calipers and a lot of fluid leaked out so naturally there would be air in the lines, but when i re installed them i bled them extensively and no air. Re-bled them again and no air in the lines but no dice. Finally i ended up bleeding air out of the master cylinder which did release a lot of air from the system, re attached the lines and did the calipers and once again, no air in the lines, but still no pressure. this time it was a little bit better but still not safe. If i pump the brakes a bit it builds pressure but it fades after a few seconds so this leads me to a few possible screw ups:

1. didn't have the car running while bleeding so its possible the lack of vacuum means I didn't have enough force from the pedal to bleed properly
2. master cylinder is garbage but there's no visible leaks so who knows, maybe bad seals internally
3. brake booster is garbage
4. I have some other leak somewhere im not seeing
5. I royally destroyed my calipers when i rebuilt them
6. brake pedal just needs to be adjusted? nah probably not thats too simple

If anyones got a similar experience let me know how you fixed it, i'm drawing a blank here. maybe i should just take it back to the shop and get them to use the power bleeder lol.
 

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My guess is the master cylinder.
It might have corrosion damage or whatever inside in certain spots. Then when you rebuilt calipers the piston inside the master cylinder might end up working in a slightly different area than before where it was better.
I had similar symptoms and changing master cylinder solved it.
 

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Like Daniel said, if you loose pressure after pumping and no fluid is lost, it have to be the master. I have actually replaced my clutch master twice, with the same problem..
I just hate driving in slow traffic with a clutch I have to pump to engage, brakes must be an even worse experience! :p
 
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