Hi all! Can anyone explain what moves the piston in the front brake caliper assembly away from the rotor after the brake lever has been released? Looking at the fiche, I don't see a spring in the caliper that would push the piston back, and it seems surprising to me that it would only be the pressure of the brake fluid flowing back towards the master cylinder - or is that really it?

Also, I saw a video of a guy replacing brake pads, and he used his hands to push the piston back into the calipers (to make room for the new pads). I just replaced my pads for the first time, by myself, and I had to use an old pad and a c-clamp (as was recommended in the tech section). Everything worked like a charm, and I replaced the pads and the brake fluid and things are working well, but I'm just wondering if I should have been able to move the piston with my hand? The bike only has 5K miles on it, and it wasn't super gunky when I replaced the pads. Should I add a caliper breakdown, clean, lube and reassemble to my list of things to do?

Thanks!

Thanks, oldNslow.

The stuff you say makes sense, and it echos what Verslagen wrote in a post in the tech section about replacing the pads:

"In theory, the caliper is free to slide in and out on the posts to adjust for variations in the rotor. Also, since only the outside brake pad gets pushed, there needs to be some slack in the caliper mount to allow it to squeeze and release. "
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1177184106/5#5

So it sounds like a significant amount of the force to disengage the pads from the rotor IS based on the negative fluid pressure. It's kind of wild to think that a single pump on the brake lever, and a single cycle of the piston in the master cylinder is enough to create that much force. The miracle of fluid dynamics! Do you think the Piston seal in the calipers also has a significant role to play in pulling the caliper piston back?

I wish Haynes made a book like this about the different kinds of motorcycle brakes:

https://haynes.com/en-us/motorcycle-fuel-systems-haynes-techbook-haynes-repair-m
anual

Thanks again, Andy.
PS - my handle on this website could well have been "middle-agedNslow"

Trivia:
I was working on someone's 70's CB Honda a while ago. As usual, the front caliper was garbage. Rust, corrosion, pitting, etc.
Told him to buy a repro caliper on Ebay. Pretty cheap, and came with new bleeder and pads.
Put it on, and not for love nor money could I get decent lever pressure. Considering that the system has only one more moving part than a cinder block, it had me wondering. I had just read an article by Kevin Cameron where he interviewed the guys at Brembo, and they said it was all about the piston rubber seals/o-rings. Bought a factory Honda o-ring and installed (perfect fit, as the part was an accurate repro). Voila! Lever presser almost immediately.
I guess the folks at the Sum Flung Dung machine works in China were better at the metal part of the repro than the rubber seal part.
The next one I bought (different supplier) worked like a charm right away.