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  1. #1
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    HOW TO: Avid Juicy Ultimate caliper/lever rebuild

    These brakesets are starting to get up there in age, and rebuilding them still costs less than buying new brakes. Universal Cycles was the only place I could find that had both rebuild kits in stock. Using the 10% VIP coupon just about covered shipping.

    Rebuilding the lever


    1. Remove the brakes from the bike, take off the mounting hardware, retract the pads and remove them.

    2. Clean the whole system off. I washed it in the sink and used an old brillo pad to scrub my hoses (they’re white and the brake dust really clings on there).

    3. Remove the reservoir cover, both bleed screws on either side of the lever and drain the fluid out. I tried to contain the highly toxic brake fluid as much as possible. It’s really nasty crap and the liberal, hippy, hemp-wearing part of my conscience won’t let me dump toxic fluid into the local water supply.


    4. Pull the rubber cover back and disconnect the lever. Drain any remaining fluid.


    5. Underneath the lever blade there are two screws. The bottom (silver) one adjusts the reach and the top (black) one holds the lever blade to the black pin that it pivots on. Top uses a T8 torx wrench, while the bottom one is a 2mm (I think) allen key. Unscrew the top one first, push the black pivot pin out the side and use the lever to pull out the threaded piston rod (may take a little force).


    6. Now you can remove the pad contact adjust. Mine got gunked up and stopped working a long time ago. Remove the c-clip and unscrew the red adjuster knob.



    7. Now we’re down to the guts. There is another, much larger c-clip that holds all the internals in place. This needs to come out first, BUT it can be damn near impossible to grab it if the worm gear is dialed all the way out. The worm gear is how you adjust pad contact. By threading it in or out, you adjust how close the worm gear sits to the piston assembly, which adjusts when in the lever stroke the piston rod contacts the piston. So use a big flathead screwdriver to thread the worm gear in, then use a small flathead to rotate the c-clip so that you have more of it to grab onto. Use pliers to pull it out. If you can’t get it to rotate, try some brake cleaner to clean it out, or a degreaser to get it unstuck.



    8. Thread out the worm gear using the big flathead again. It will come out and so should the piston assembly. It might fly out, as it does have a spring on the end.

    9. The lever is now ALMOST fully disassembled. There are 3 bushings in the lever – two that the lever blade pin rides on (on the inside), and one that the end of the pad contact adjuster sits on (on the outside). Remove these and clean the crap out of everything. You can see my worm gear was really filthy, as was the piston assembly. I used a combination of a toothbrush, brake cleaner, dish soap, water and compressed air. For the lever, the trick is to clean all the old brake fluid and grime out, and completely open up and dry out all the fluid passages. I used an air compressor to blow out any residual water – water neutralizes brake fluid, so even a little bit is bad news bears. Cleaning the internals out is easy.


    10. Rebuilding the piston assembly: pull the spring off the end, and remove the little grey plastic piece. Then remove the tapered rubber seal. You will replace this piece, make sure the orientation is correct. The larger end faces the spring. You will also replace the o-ring on the white plastic piece. Then put it all back together, and put it into the lever.



    11. Clean off the worm gear, and clean the black plastic piece on the inside of it. The piston rod pushes this piece against the piston assembly independently of the worm gear to actuate the brake. If your worm gear is worn or damaged (same goes for the red adjuster that meshes against it) you may need to replace those pieces, which are not included in the lever rebuild kit but ARE included in the lever parts kit. Assuming you don’t care about pad contact adjust, you can just reinstall them and not worry about it. Replace the worm gear and thread it in so you can reinstall the large c-clip (a new one is provided). It may be tough to thread it in, since you have to push it against the piston spring. Now you can dial it back out once the c-clip is in there. Reinstall the red adjuster – there is an o-ring and a small washer on it, replacements are included in the rebuild kit for both of these as well. Make sure to reinstall the bushing on the end before you reinstall the smaller c-clip.

    12. Screw the piston rod back into the lever blade and push the piston rod back into the worm gear/piston assembly. Reinstall the lever pin bushings, the lever pin and reinstall the black set screw that holds it in place. You may need to tinker with the reach adjust in order to line up the hold in the lever with the hole in the lever blade in order to push the pin in.

    13. Reinstall the bleed screws (replaced) and the reservoir cover, with the new rubber bladder.

    Rebuilding the caliper


    Parts included


    1. Remove the black bleed screw and remove the banjo nut. Then you can remove the hose from the caliper. Note that the banjo fitting has an o-ring on either side.




    2. Make sure the pistons are fully retracted, and I mean FULLY. If they’re not, you won’t be able to remove them.

    3. Use an 8mm allen key to screw in the red caliper bolt. It screws into the lever, so turn it to the right. You might want to use some WD-40 or PB Blaster to penetrate the threads. If they’re stuck you can round out the aluminum pretty easily.


    4. Push the external piston out and remove the red cap. The tolerances are TIGHT so if the internal piston isn’t fully retracted, you’ll never get the external piston out. Now you can use an air compressor where the banjo bolt connects to push out the internal piston.


    5. Inside the caliper are two piston seals that sit in a groove. Use a dental pick to pull them out.



    6. Clean the crap out of the caliper. As mentioned with the lever, residual water is bad. I once again used an air compressor to thoroughly clean it out.

    7. Replace the piston seals, make sure they’re seated fully. Two new pistons are included in the kit (both sides are identical). Install the inner piston, then the red cap (also new) and the outer piston.


    8. As far as reinstalling the banjo fitting: there is a new banjo nut included and two new o-rings. One o-ring goes on either side of the banjo fitting.



    Hoses
    1. Cleaning the hose. I have white hoses – I make up for the fact that I can’t ride for **** by being flashy. So I scrubbed them down. But seeing as the passage in the hose is incredibly narrow I also wanted to clean that out and make sure there were no contaminants in there. So I rinsed it out with water and blew it clean with the air compressor several times over, before reinstalling it.
    2. When you’re finally finished, bleed the system. Pulling it apart really gives you an understanding of the bleed procedure. Example: if the worm gear is dialed in, it’s not possible to get a full bleed. Pad contact has to be all the way out.


    I bled my brakes and have had great performance so far. No more sticky pistons and my turkey warble has drastically decreased. YMMV.

  2. #2
    One Gear
    Reputation: .40AET's Avatar
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    I did the same thing a few years back and was stoked for about a week. Good luck......but the sticky pistons will likely be back soon.

    Nice tutorial

  3. #3
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    I am rebuilding my triggers and I am wondering the importance of the worm gear and being able to adjust it. If I set it correctly, 3 turns out from all the way in do you really ever have to adjust it after that? or would you just replace your pads at the point you might adjust it?

    I have one red worm gear that is destroyed and the silver metal gear has 2 small nicks out of it so I am thinking I could just replace the red worm gear. Not sure if this kit includes the silver metal worm gear.
    Amazon.com : Avid Juicy Ultimate/Code 7 Worm, Gear Kit : Bike Brakes : Sports & Outdoors


    Here is what my worm gears look like
    Attached Thumbnails Attached Thumbnails HOW TO: Avid Juicy Ultimate caliper/lever rebuild-stripped-worm-gear.jpg  


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