Hey everyone! This is my first post here so sorry if I am not in the right spot.
I am working on Wreck Racing's 2025 comp entrant and we did a full brake component swap from the original donor car. Every component was separated from the car during this years build, so the whole system was dry.
I am struggling to get the brake to become firm and I am wondering if it's a skill issue with my bleed or if there's special procedures for a dry ran system. We do have braking though; during our test run the brakes performed decent and were able to stop the car at speed, however the first half of the pedal travel is soft.
The brake system is off a B7 S4 (along with the entire drivetrain lol), and we kept ABS. Do i need to run a special Audi software to cycle the ABS pump? Would that be causing a mushy pedal even after several bleeds at each wheel? Could the master cylinder be toast? I am at a loss and theres a ton of conflicting information online.
Sounds like you still have air in the lines somewhere. Cycling the ABS motor might help, might not. If you are not using a pressure bleeder already, it will help a lot. You might also try cracking lines at threaded joints elsewhere in the system while bleeding, not just the bleed nipples at each wheel.
Regarding skill issue, my process for manually bleeding brakes without the pressure bleeder is: I have my helper do at least 3 slow, full pumps of the pedal, they hold it down, I crack the bleeder while they keep holding the pedal (it should move down as fluid is bled out), then I tighten the bleeder, THEN helper lets off the pedal and pumps up again.
It also helps to use a bleed bottle:
in a perfect world, the master cylinder is the highest point in the system and the tubes and hoses run downhill the whole way. any place the plumbing has to go "up and over" gives air a place to hide. pressure bleeder can help with that.
i don't think the ABS is the problem, as it is a flow-through device. any passages or accumulators that could "hide" air are isolated from the flow-through portions, and would only be exposed during a pressure control event.
Bleed the master cylinder first, then gravity bleed each corner starting with furthest from the master cylinder. A few hard stops on gravel or grass should get the ABS fired up and move any air out of the ABS unit but you should be able to get a halfway decent pedal without the ABS being activated.
