Can't get 2005 Bonn front brake caliper piston wide enough

[homeboy517]

I am trying to change the front roters and pads on my 2005 Bonneville SE. I've got the caliper and rotor off just fine but I cannot seem to get the caliper piston wide enough for new rotor and brake pads. I have checked multiple sources so I amd confident I have all the correct parts. Is there some nut or bolt I didn't remove or loosen that will allow me to depress the caliper piston a little further?

Thanks, Al

[DCJREDLINE]

Did you remove the master cylinder cap? Other than that I cant think of anything but wrong parts that would cause this.

[00Beast]

What are you using to compress it? I use a large c-clamp and one of the old pads to compress the piston, so it doesn't go in too far.

[homeboy517]

All: Thanks for the suggestions/replies.

I too am using a large C-clamp and one of the old pads to compress the caliper piston. I have not tried removing the master cylinder cap. Never occured to me that there might be pressure behind the piston preventing me from depressing it all the way open. I will give than a try. Little chance I have the wrong parts. Not only have I tried multiple parts, I also have a vernier caliper so I can measure the thickness of the rotors and pads.......but it's worth another check to be sure.

Thanks again for your suggestions!

[Archon]

The piston should lay level with the caliper face when depressed all the way. If it won't compress all the way, something is either binding in the caliper (which will require it being replaced) or contamination in the fluid is blocking the passages. You can try loosening the bleeder screw and see if it will compress further. Flushing the system would be a good idea.

[myfirstbonnie]

[homeboy517]

Thanks all for your suggestions. Removing brake fluid via the master cylinder or the bleeder valve on the caliper worked.