tuxman wrote:4) Install back onto rotor, but don't tighten the bolts all the way. Allow the caliper to be loose enough to float left to right but tight enough not to float up and down..
..are you saying leave the caliper fixing screws loose ! ??
What is preventing them backing off and falling out..leaving you brake-less !!
By leaving those bolts loose, you weaken the caliper mounting by 75% !
does not sound like good advice or a sensible way to prevent brake noise.
If you really need a "floating" caliper, at least use shoulder bolts that can be tightened properly.
I would agree, don't leave the bolts loose please!
The factors that I think play the biggest part in the brake squeal this bike has are;
1. Soft frame and fork material allowing for resonance to be magnified.
2. Resonance from poorly aligned mount.
3. Factory contaminated pads and/or rotor.
The mounts should be machined parallel and the paint removed, using a professional technique and tool such as the Park Tool DT-1
, but since this is hard to find in our local shops, I opted for the Avid BB5 Tri-Align brakes (and rotors) which compensate nicely for the poorly aligned and soft Zuma disc brake mounts. I did remove the paint from the mount surface prior to mounting the caliper adapters to eliminate any possibility of the paint softening from rotor heat, causing a soft surface which allows vibration to magnify. (so the "experts" seem to think)
Pulsing brakes are caused by either oil on the rotor, or a poorly stamped rotor with thick and thin areas of the rotor, which is the actual problem with the disc brake rotors I have had this problem with on Currie iZip bikes. You need a new rotor if your new bike is pulsing during braking and you have cleaned the rotor thoroughly with common isopropyl alcohol and the problem still exists. Remember to use rubber or plastic or nitrile gloves when handling brake rotors so your finger oil doesn't deposit on the rotor.
Other suspects are loose spokes and the Zuma spokes do loosen after a few rides so they too should be tensioned or at least checked for proper tension.