Did the Dragon this past weekend and on some downhill runs the pedal got spongy. Considering:

1.) Last spring bleed/drained/replaced brake fluid. Did some downhill runs but no issues.
2.) Before going to the Dragon this past weekend, put on Yellow Stuff pads, ECS rotors, SS lines on the front, left the rubber lines on the rear and drained/replaced the 5 month old fluid with Motul 600.
3.) Used a 1/2 liter of 600 to flush out the old and then used another 1/2 liter to flush and fill again.
4.) If I push the pedal down cold, notice no leakage around the master cylinder seals. No leaks around any fittings as well.
5.) Sent Motul an email on whether they have had any bad batch reports.
6.) Used same process I have for 40 years on bleeding.

So Gods of MINI Mind Trust, what are your thoughts? I am wondering whether at running temperature the master cylinder seals are letting fluid bypass.

 

Make sure the hard line is not leaking on a hairline crack. Make sure the master cylinder and brake booster seals are good. If you have a small leak on a seal where it can lower the vacuum and pressure.

Sometimes I have to bleed twice to get all the air out. So bleed it one more time and maybe a bubble got in there?

 

Going to do some more bleeding once I have some more Motul in hand. There was another NAM member at the Dragon this past weekend that lives in my area of the State. He tracks and autocrosses his R53 as well as doing all the wrench turning. Throw in some computer skills and he is one very good R53 source. If the bleeding does not work, his suggestion was looking at the ABS module, something I was also thinking about after my cold pedal test this morning.