new pads cause a ton of drag on rotor
I've had this problem ever since I got this set of Hayes Mag's.
When I change pads I push the old pads all the way out with a screwdriver-compressing the pistons as far as they'll go. All my other Hayes work fine when changing pads this way. I don't want to bend the pins.
When the new pads go in I have a hard time turning the wheel.
I had been sanding the pads a bit to get them to free up but obviously you lose a bunch of service life.
I also tried to bleed off some brake fluid hoping to allow further retraction, still no good.
After this last change(again problematic) I decided to swap out to an old caliper from a spare set of HFX9's, bled them, installed pads and to my delight the wheel turns freely.
Obviously I'm delighted that the rear wheel spins easily with a new set of pads but I was perplexed as to why the old caliper was so problematic.
Anyone have any ideas? Maybe a problem machining the bores of the old caliper?
My guess is the pistons weren't fully retracting. A lot of times when pads are heavily worn a lot of the piston is exposed and gets covered in dirt, which will either wear the piston a little and make it hard to push in, or get pushed into the small gap b/w piston and bore, also meaning the piston feels like it has gone as far as it can.
I think I've been having the same problem. What's the fix?
First things you should check on are the following;
Take the wheel off then,
1-Make sure the pistons are fully retracted using old pads to pry the pistons fully back in there bore. I use the old pads because I've bent the pins on the pistons by accident and you'll ruin new pads if you pry on them.Use either a flat blade screwdriver or similar item.Then take the pads out and make sure there is no dirt or foreign debris in the pad area, use a brush to scrub out any matter.Make sure the rubber boot surrounding the piston is flush with the top of the piston.
Don't use auto brake cleaner! Don't clean the rotor or pads with anything but alcohol.
2- If the pistons seem fully retracted and the brakes still drag make sure the caliper is centered over the disc rotor.Adjust as needed.
3-If you still have drag try and let out a few drops of brake fluid out of the master via the screw-just 2 or 3 drops.Sometimes I've noticed the fluid seems too full which theoretically won't allow the pistons to return fully in there bore.If you let out too much fluid you'll get a soft brake action and will have to add fluid or bleed the brakes.
If all of this fails there is something wrong beyond the normal obvious stuff-as was my case for a year. I think my issue was perhaps a manufacturing defect, no matter what I did they still dragged, I would have to sand the pads a bit to get them to free up and sand away a bunch of the brake life as well.
I ended up changing the caliper and re-bleeding-all was good then.
I would go to the Hayes website and check out there instructions on how to not only change pads but there is also a trouble shooting section, I also think there is a forum.