Results 1 to 7 of 7
  1. #1
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    19

    avid 7 problem...part II?

    Hi all-

    I'm pretty new to hydraulic brake maintenance (had v-brakes forever) and I can't figure out what's wrong with mine. I bought a new SJ elite a few weeks ago and have had problems since the beginning. My main problem is that the piston in the caliper never seem to go all the way back in after i apply the brake. For the past couple weeks i've had a problem with the rotor rubbing against the brake pad. I finally got the caliper adjusted right, and then as soon as I applied the brake, the piston came out to make contact with the disc, and then went back in, but only half way, thus leaving me with rub again.

    The same happens in the rear. I tried to fix them today, but ran into some trouble. I had the pads off and used the brake lever to see how far out the piston would go, and sure enough i cranked the piston right out of the socket it sits in. I lost some brake fluid while it was out, and even though i pushed it back in and put the pads back on, i get no response from that brake now.

    How do i go about fixing the rear brake, and what is the problem with the piston in the front not retracting?!

    --Brandon

  2. #2
    mtbr member
    Reputation: Lumbee1's Avatar
    Join Date
    Dec 2004
    Posts
    1,909
    Quote Originally Posted by Bwalen
    Hi all-

    I'm pretty new to hydraulic brake maintenance (had v-brakes forever) and I can't figure out what's wrong with mine. I bought a new SJ elite a few weeks ago and have had problems since the beginning. My main problem is that the piston in the caliper never seem to go all the way back in after i apply the brake. For the past couple weeks i've had a problem with the rotor rubbing against the brake pad. I finally got the caliper adjusted right, and then as soon as I applied the brake, the piston came out to make contact with the disc, and then went back in, but only half way, thus leaving me with rub again.

    The same happens in the rear. I tried to fix them today, but ran into some trouble. I had the pads off and used the brake lever to see how far out the piston would go, and sure enough i cranked the piston right out of the socket it sits in. I lost some brake fluid while it was out, and even though i pushed it back in and put the pads back on, i get no response from that brake now.

    How do i go about fixing the rear brake, and what is the problem with the piston in the front not retracting?!

    --Brandon
    Your new problem is that you now have to bleed the brakes. The brake line has air in it and air compresses easily. I am simplifying the process here but you need to add fluid at the caliper and push the air out through the lever on the handlebar.

    Your original problem would have been covered by the LBS if the bike is only a few weeks old. I don't think rubbing pads is a common problem with Avid Juicys, especially new ones. You might want to check your bike over and make sure it wasn't a demo bike and the brakes just need to be rebuilt.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    19
    yeah i figured that i now need to bleed the line for the back brake.

    i might take the bike to the LBS to have them check it out for a second time. There's also the side of me that figures I should get to know the parts and find out how to fix it myself through the use of a manual and all that. Oh and the bike had to be ordered and was never demo'd. A specialized rep dropped the bike off in a box and it was assembled at the shop.

  4. #4
    Calm Like a Bomb
    Reputation: pipes10's Avatar
    Join Date
    Mar 2007
    Posts
    2,042
    for rotor rub loosen the cps bolts then squeeze the lever 5 or 6 times, then squeeze and hold. While holding the lever, lightly snug the CPS bolts to hold the caliper in place. Spin the wheel and check for rotor drag. If there is drag, loosen the CPS bolts and repeat. Once there is no drag, gradually tighten the bolts, alternating from one bolt to the other, steadily increasing force until each bolt is at the specified torque. Repeat for the rear brake.

    that's right out of the manual

    also, try putting a business card between the rotor and the pad and squeeze the levers a few times....or do the same but loosen the cps bolt before squeezing...then tighten the cps bolts while squeezing the lever

    works for me but i'm a noob

  5. #5
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    19
    I will try those methods this weekend and see what happens, thanks everyone!

  6. #6
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    19
    So i have tried the following things-

    The brake bleed kit by Avid is super easy to use, and only took me 20 minutes to do for both brakes, and I can already feel a dramatic improvement in braking power.

    The downside is that I STILL can't get my brakes aligned so they don't rub on the pads!

    I tried the business card idea and also the CPS adjustment, and I still can't seem to get things right.

    I've noticed that the brake pads never fully retreat into their spaces on the caliper. Is this normal? I almost feel like the rotors are too wide for the caliper.

    Anyone else have any ideas on truing the rotor with the caliper?

  7. #7
    mtbr member
    Reputation:
    Join Date
    Aug 2005
    Posts
    196
    Quote Originally Posted by Bwalen
    So i have tried the following things-

    The brake bleed kit by Avid is super easy to use, and only took me 20 minutes to do for both brakes, and I can already feel a dramatic improvement in braking power.

    The downside is that I STILL can't get my brakes aligned so they don't rub on the pads!

    I tried the business card idea and also the CPS adjustment, and I still can't seem to get things right.

    I've noticed that the brake pads never fully retreat into their spaces on the caliper. Is this normal? I almost feel like the rotors are too wide for the caliper.

    Anyone else have any ideas on truing the rotor with the caliper?
    The pads don't fully retreat into the caliper they will stay out where they are almost touching the rotor. I use a piece of white paper when it bright out and look straight down the caliper to see if I can see the tiniest thread of light to either side of the rotor. I will usually have to move my head/eye around in order to see the light.

    Some suggestions to try.

    Remember that the QR on your bike and how tight it is will affect the orientation of the rotor to the caliper (as will crappy QRs). I have to fiddle to get things right after I remove a wheel (especially my front one). I make sure the QR is all the way into the dropout and then snug it tight. spin the wheel and do it again till it is right. With practice I no longer have to do this multiple times I just seem to know when it is right.

    The pad contact adjuster, is it in all the way? mine are juicy fives so I don't know what exactly one does, just something to possibly look into.

    If the brake isn't overfilled or something like that, it may be just the CPS adjustment. When I installed my brakes it took me a little bit to get the knack but when I did it was worth it, I got perfect alignment which is something I hadn't had with non avid brakes. I tightened the bolts down maybe ten times to get things absolutely perfect. I find treating it like truing a wheel works best, find the spot that it catches on and tighten the caliper down on it. I don't like the whole business card thing because you should get it to align perfectly to your rotor not to your rotor and a business card (which will compress under the mighty force of your brakes caliper). Also make sure your pulling fairly hard on the lever when doing the tightening, like a hard stop on a fireroad or pavement.

    If you still can't get it after this much time, it never hurts to go to a bike shop and ask their mechanic. Its good to figure stuff out on your own but there is no sense in beating your head against a wall, especially if it is something he can spot in a few minutes, you still learn what the problem/solution is.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •