I rebuilt my brembo calipers and now I'm having a problem where the pedal goes to the floor and I have to pump it a few times. I did bleed them of course but I suspect what's happening is that the new seals are retracing the pistons too far. I've read up on this and it seems to be a common problem. If I pump a few times, the pedal gets solid, but then if I wait a few seconds, then the next time it will go to the floor. Apparently it goes away after a while as the seals break in.

I installed a slightly more worn set of pads and pumped the pedal to try to get the pistons out a bit more, then squeezed in the current pads. That seemed to help a bit but it's still a problem. The thing is, I have a track event tomorrow...there's no way I can do it with the brakes like this. Is there anything else I can do to speed up the process? I only have a few hours to get this sorted this evening or I will have to miss the event. I know that's more than likely what will happen now but any suggestions are welcome. Thanks!

 

Pull the pads out and apply the brakes (not all the way but give them plenty of travel to stretch)

I bought new calipers and bled at least 20 times before figuring out it was the fresh seals.

 

Thanks...I tried that intially and tried to watch the pistons on the driver's side front to make sure I didn't let them out too far. They didn't seem to be moving at all but when I stopped and looked closer, I discovered that one I couldn't see had come out all the way to the disc while the others had stayed all the way back

I might have to get creative with clamps or shims of some kind to get them to come out evenly.

 

Reimu, how long did it take to break in your new seals? Mine have improved a lot and I was able to do a track event last weekend with no issues, but the pedal is still not 100% right. It bites a bit low, although it still stops the car well. A few light pumps and it gets really high, and feels perfect. But by the time I get to the next set of lights, it's low again. I have put a few thousand miles on them since the rebuild.

I'm wondering if it could be the master cylinder on the way out?

 

You could put in some worn pads, or even a scrap of metal about 1/4" thick...

What's your technique for bleeding? You're sure the calipers are on the correct sides? I've seen people accidentally swap left and right so the bleeders are pointed down...

I find that sometimes it helps to use the Motive pressure bleeder, have someone step on the pedal, and tap the brake lines (hard, flexible, and caliper) with a hammer to dislodge any air bubbles that are sticking to the internal walls by surface tension.

 

p.s. You did coat the seals and sides of the pistons with brake fluid as you were reassembling them?

 

I have a set of pads that are slightly more worn that my current ones but not much. I tried those originally but I'll look for something else a bit thinner.

Calipers are definitely on the correct sides, bleeders up I bleed with a Motive pressure bleeder and I do all those things when I'm bleeding - press the pedal a little, tap the calipers and lines etc.

Yes I did it exactly the way you show it in your video. I also compared the new seals with the ones I removed to make sure the sizes were correct.

 

When using the Motive Power Bleeder, I push the pedal all the way down and up (slowly) a few times.

Did you install new rotors? The used pads may be worn a little slant/uneven, which may be the reason you have to push the pedal far down?

 

I didn't install new rotors lately. The pads were installed new on moderately used rotors earlier this year, but I have a good few miles and several track events on them.