• 06-11-2010
    billips1002
    Fantom 29 Pro SL Brake Squeal
    I've got a squeak squeak squeak coming from my RR Avid Elixir.:crazy: It only makes noise when brakes are not applied after riding the bike for 1 or 2 miles but then does not stop. The squeak noise goes away for a short period of time if I:
    A) Apply the brakes
    B) Clean the rotor with isopropyl alcohol
    C) Run water over the pads/rotor from my camelback

    It appears that there is contact between the pad and rotor on one side. I've tried adjusting the caliper position several times but it never seats so that the rotor is centered between the pads.

    Any suggestions on how to remedy this problem?

    I thought about pulling the rotor to make sure it's true but it really doesn't seem to be the problem.

    I also thought about applying a bit of grease behind the pad. I work in automotive and you'd be surprised at the number of development issues we solve by applying a bit of grease here and there (including brake squeal issues).

    Could it be the pad return spring is not pulling the pads away from the rotor far enough and needs to be replaced?

    I've started to think that the disk brake system is more trouble than it's worth. Everything else on the bike has been quite trouble free through about 800 miles. The noise drives me nuts and makes me less enthusiastic about riding the bike.

    Thanks
  • 06-11-2010
    Jisch
    If the squeak only comes around once a revolution, your disk is probably bent/warped. You can easily straighten it with an adjustable wrench, just go a little at a time. You can see where it is bent by watching as the disk goes through the pads.

    Sometimes one of the calipers gets gunked up with brake dust or whatever and that one pad doesn't retract all the way. If you watch the pads they should both retract the same amount after you release the lever. If you have a sticking caliper, pull out the brake pads and blow it out with an air compressor - that has worked for me several times.

    It could be that you need to mechanically center the caliper, meaning putting a washer in to move the caliper out. Of course this only works if its offset to the inside. I had a bike/caliper combo where I needed to file a little material off the inside of the caliper to get it to sit closer in to avoid rub, that that was a pretty extreme measure.

    Also there's a well known issue with Avid hydro brakes (check the brake forum) where they make a huge squawking noise that vibrates through your frame - it doesn't sound like that's your problem, but I found that was fixed by reseating the pads, which means taking sandpaper to them to rough them up, but there's a thousand fixes for that over in the brake forum.

    I wouldn't give up on disks, they are miles better than vee brakes. Worst case scenario you can go to BB7s, where you adjust the pads individually with a knob.

    John
  • 06-11-2010
    BigSteve in CO
    "It appears that there is contact between the pad and rotor on one side. I've tried adjusting the caliper position several times but it never seats so that the rotor is centered between the pads."

    Sounds like you are new to disc brakes. If you can't align the brake, I'd take it in to a shop and ask them to show you how to do it. It'll cost you $20, but it would be a good investment.

    Are you following this procedure?
    1. loosen caliper mounting bolts
    2. squeeze lever a few times, the squeeze and hold
    3. use other hand to tighten mounting bolts
  • 06-11-2010
    billips1002
    Quote:

    Originally Posted by BigSteve in CO
    "It appears that there is contact between the pad and rotor on one side. I've tried adjusting the caliper position several times but it never seats so that the rotor is centered between the pads."

    Sounds like you are new to disc brakes. If you can't align the brake, I'd take it in to a shop and ask them to show you how to do it. It'll cost you $20, but it would be a good investment.

    Are you following this procedure?
    1. loosen caliper mounting bolts
    2. squeeze lever a few times, the squeeze and hold
    3. use other hand to tighten mounting bolts

    That's not the problem. I assembled my bike myself and I've been through this procedure multiple times.

    The caliper always seats too far outboard when I use the Avid alignment procedure. I've followed the directions completely and I use a torque wrench each time I perform the alignment procedure. There's a slight gap to the outboard pad but constant contact on the inboard pad.
  • 06-11-2010
    SuperJETT
    Just in case you haven't tried these tricks: Have you tried putting a business card in on the tight side while tightening it down? I assume they have the Avid cps washers, so put some grease on those so they move easily on each other. Spin the wheel hard then slowly grab the brake lever so the vibration from stopping the wheel helps center the caliper. Tighten the bolts evenly in very small increments.

    If you've done all those options and some of the other tricks, barring switching calipers, you could use a Dremel and slot the mounting holes slightly to allow centering. It won't take much.
  • 06-11-2010
    billips1002
    Quote:

    Originally Posted by SuperJETT
    Just in case you haven't tried these tricks: Have you tried putting a business card in on the tight side while tightening it down? I assume they have the Avid cps washers, so put some grease on those so they move easily on each other. Spin the wheel hard then slowly grab the brake lever so the vibration from stopping the wheel helps center the caliper. Tighten the bolts evenly in very small increments.

    If you've done all those options and some of the other tricks, barring switching calipers, you could use a Dremel and slot the mounting holes slightly to allow centering. It won't take much.

    Thanks,

    I'll try those tricks. So far it seemed to me that I have pad/rotor contact even with the caliper positioned on the CPS as far inboard as possible. But aligning CPS w/ a business card to give a little extra clearance might do the trick. Grease on the CPS washers couldn't hurt either.

    I've been aligning the caliper using CPS with the wheel in a static position but that may not be ideal.
  • 06-11-2010
    BigSteve in CO
    Improper frame alignment? That would really suck to have to swap out the frame with bikesdirect.
  • 06-11-2010
    billips1002
    Quote:

    Originally Posted by BigSteve in CO
    Improper frame alignment? That would really suck to have to swap out the frame with bikesdirect.

    That would suck but I don't think it's the culprit. There was no issue when the bike was newly assembled. It's been ridden pretty hard since. I have been learning trail riding, so several crahses, though none too severe as to cause more than superficial injury.

    However, I can say quite certainly that my RS Reba fork is defective. From the first time I installed the wheel it's set off-center to the port side by a visually noticeable amount. I've trued and dished the wheel to rule out the wheel as the root cause but it never centered in the fork.

    I haven't put up too much of a stink over this because I don't think it has much impact on the performance of the bike. Thoughts?

    BikesDirect told me to contact SRAM directly about the fork issue but I've been kind of avoiding doing so since it would probably mean I'd have to take the bike into my Trek/GF shilling LBS, which I am not looking forward to.
  • 06-11-2010
    72Blazer
    If only one side seems to be rubbing even after using the business card trick to center the pads then maybe the return spring is the problem.Or since you said you had 800 miles on it and have ridden it hard maybe there is some crud behind or around the pad that won't let it return.Take the caliper off and clean it real good and re-assemble.
  • 06-12-2010
    billips1002
    Quote:

    Originally Posted by 72Blazer
    If only one side seems to be rubbing even after using the business card trick to center the pads then maybe the return spring is the problem.Or since you said you had 800 miles on it and have ridden it hard maybe there is some crud behind or around the pad that won't let it return.Take the caliper off and clean it real good and re-assemble.

    Great suggestion! That could certainly be the problem. It's not hard to pull the caliper and remove the pads and clean it out. So I'll do that anyway.
  • 06-12-2010
    Jisch
    I was checking over one of my bikes last night and noticed my front pads needed changing. When I pulled the old ones out I noticed they were not worn evenly. When I tried to push the calipers back in one side wouldn't move at all. I blew it out with the air compressor and it still wouldn't move.

    I got it to move by squeezing the brake lever with no disk in place, both calipers moved, then I could push them both back in. You have to be careful if you do this so that you don't go too far, but it got the calipers to move and everything seems good now.

    John