I just rebuilt my calipers (2000 S) with new Centric seals and new silicon dust boots from racing brake (supposed to be more high temp resistant, but can fail if brake fluid gets on them. We'll see if it was a good idea or not
). It wasn't too bad, and after I got the calipers back on the car I bled them twice: 1 time all the way around the car with the motive bleeder (and with the pistons fully retracted), and then I pumped the brakes to seat the pistons on the pads, and then did another bleed with the motive, accompanied by a few pedal pumps.
I got a lot of air out the first time, as expected, and I got some out the second time too.
Then I took a drive, and got the following behavior: braking power is the same as it ever was, except the pedal travel is a little longer than it used to be, like I have to push the pedal down a little further before I get to the actual braking.
Doing a few searches has led me to some theories:
- I still have some air in the calipers.
- The new seals are pulling the pistons back into the caliper, and that extra pedal travel is moving the piston onto the brake pad, and when I release the pedal, the seal is pulling the piston back. If so, this should resolve itself after some driving.
I'm going to another bleed, this time the "old fashioned" way with 2 people, and using the brake pedal to push out the fluid. This will generate a lot more force than the motive and may help to dislodge bubble. Also I worked the brakes pretty good when I was on my test drive, and activated ABS a couple times, so maybe that dislodged the bubbles to the top. I may also tap the calipers with a rubber mallet to dislodge any air bubbles...
If this doesn't resolve it, I am not that excited about "waiting" for it to solve itself in regard to the pistons seating on the brake pad and not getting pulled back by the seals, since I am going to Roebling this weekend.
Just wondering if anyone has ever seen this, as I know a few folks have rebuilt their calipers.
Thanks
Steve
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