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Old 11-02-06, 07:48 AM   #1
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squeeky breaks

My Avid Juicy 7 breaks squeek very loudly. Any suggestions? Also the discs are warped some. What should I replace them with?
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Old 11-02-06, 08:39 AM   #2
C Law
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are they brand new? they might take some rides to stop squeeksing

Have you ridden in the rain recently?

juicys are notorious for squeeling in the rain. But in my experience all brakes squeek in the rain

you can try cleaning the rotors with some denatured alcohol.

As far as truing them, I find that taking a long downhill with the brake lighty applied with help to straighten them out. If it is real bad, bend them by hand or by needlenose pliers (lightly). Use a clean towel either under your fingers or pliers to not contaminate the rotors.
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Old 11-02-06, 09:38 AM   #3
Pete Hamer
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I've had some luck with CRC disc brake quiet.

Here is Avid's disc brake Bed-In oricedure

Proper Disc Brake Bed-In Procedure
Ever wonder why disc brakes don't have full power right out of the box? Click to find out how to get full power from your brakes and keep them quiet!

**Much of this great information came from Pad and Rotor Bed-In Theory, Definitions and Procedures: Removing the Mystery from Brake Pad Bed-In
by Matt Weiss of StopTech and James Walker, Jr. of scR motorsports. Thanks guys!

What is bed-in anyway?

Simply stated, bed-in is the process of depositing an even layer of brake pad material, or transfer layer, on the rubbing surface of the rotor disc. That's it. End of discussion. Ok, not really, but although bed-in is quite basic in definition, achieving this condition in practice can be quite a challenge, and the ramifications of improper or incomplete bed-in can be quite a-a-n-n-o-o-y-y-i-i-n-n-g-g.

Abrasive friction and adherent friction

There are two basic types of brake pad friction mechanisms: abrasive friction and adherent friction . In general, all pads display a bit of each, with abrasive mechanisms dominating the lower temperature ranges while adherent mechanisms come more into play as pad temperature increases. Both mechanisms allow for friction or the conversion of Kinetic energy to Thermal energy, which is the function of a brake system, by the breaking of molecular bonds in vastly different ways.

The abrasive mechanism generates friction or energy conversion by the mechanical rubbing of the brake pad material directly on the rotor disc. In a crystalline sense, the weaker of the bonds in the two different materials is broken. This obviously results in mechanical wear of both the pad and the rotor. Consequently, both pads and rotors are replaced when they are physically worn to their limit and are too thin to endure further service.

The adherent mechanism is altogether different. In an adherent system, a thin layer of brake pad material actually transfers and sticks (adheres) on to the rotor face. The layer of pad material, once evenly established on the rotor, is what actually rubs on the brake pad. The bonds that are broken, for the conversion of Kinetic to Thermal energy, are formed instantaneously before being broken again. It is this brake pad-on-transferred brake pad material interaction on a molecular level that yields the conversion process.

With the adherent mechanism there is much reduced rotor wear as compared to abrasive mechanism, but it's not a free lunch – pads now become the primary wear element in the braking system.

Bedding fundamentals

In general, bed-in consists of heating a brake system to its adherent temperature to allow the formation of a transfer layer. The brake system is then allowed to cool without coming to rest, resulting in an even transfer layer deposition around the rotor circumference. This procedure is typically repeated two or three times in order to ensure that the entire rotor face is evenly covered with brake pad material. Sounds easy, right? Well, it can be if you have the proper information.

The key to a successful bed-in is to bring the pads up to their adherent operating temperature in a controlled manner and keep them there long enough to start the pad material transfer process. The recommended procedures below should provide you with the information you need to select the bed-in procedure appropriate for your application.

Bed in procedure

When a system has both new rotors and pads, there are a few different objectives for bedding-in your brake system: heating up the brake rotors and pads in a prescribed manner, so as to transfer pad material evenly onto the rotors and put a final heat treatment into the rotor; and maturing the pad material, so that resins which are used to bind and form it are ‘cooked' out of the pad.

The first objective is achieved by performing a series of stops, so that the brake rotor and pad material are heated steadily to a temperature that promotes the transfer of pad material onto the brake rotor friction surface. Additionally, you are providing a heat treatment for the rotor. There is one pitfall in this process, however, which must be avoided. The rotor and, therefore, the bike should not be brought to a complete stop, with the brakes still applied, as this risks the non-uniform transfer of pad material onto the friction surface. The second objective of the bedding-in process is to mature the pad itself. This ensures that resins which are used to bind and form the pad material are ‘cooked' out of the pad, at the point where the pad meets the rotor's friction surface.

Dealer Service recommends firm (not hard), consistent application of the brakes at a speed of ~12mph to slow the bike to walking speed. Re-accelerate back to ~12mph and repeat 15 or 20 times. You should notice the brakes start to feel "normal". Now for the fun part. Bring the bike up to a higher speed, 15-18mph and really get on the brakes (DON'T LOCK THE WHEELS) and bring the bike to walking speed quickly. Repeat 8-10 times. Let the brakes cool by riding, and cool your legs down too.

You're done!
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Old 11-02-06, 09:44 AM   #4
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try some copper grease #BEHIND# the pads after you've sorted the warped discs.
Warranty claim perhaps?
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