|
The idea with disk brakes is that you want an exactly flat disk and when the brakes are off, the pads should be JUST off the disk surface, so that when the brakes are applied there is very little pad movement required.
Old fashoned disk brakes were a flat or dished rotor bolted to the hub with a caliper bolted to the fork. and the caliper gripped the disk. The problem with this is that any lateral movement or warping in the disk moves the pads in the caliper apart and they are a fair way from the disk. When the brakes were applied, the pads had a far way to move before the disk was gripped and the lever would move in further to the grip before th brakes worked. You could also get uneven pad wear.
To help this problem, a floating system can be used. Triumph seems mostly to use a floating caliper system where the caliper is mounted on a carrier with lubricated pins that allow lateral caliper movement so that it can automatically align with the disk rotor. This system works well as long as the system is lubricated, not corroded and not crudded up wit dirt and brake dust so the caliper can move easily and freely. This usually requires rubber seals and the like and also weighs a bit more. My Triumph Tiger's original Nissin brakes use this system. This system is actually required when single sided calipers are used - ie one pad is fixed and the caliper only has one or two pistons on one side. In single sided calipers, the force from the master cylinder lever is cut in half by one piston pushing on two different brake pads on each side of the rotor. These calipers are cheaper to make that double sided, multi (2, 4 or 6)piston calipers.
Multi-piston calipers (often called "2, 4or 6-Pot calipers) work more efficiently and transfers a larger area of friction to the rotor because pressure is exerted equally on both sides of the rotor by a series of individual pistons working together.
There are a few potential disadvantages of a floating caliper system. The first is that as the whole disk rotor is a unit and bolted to the hub, disk warping can be an issue if the hub is not aligned and exactly flat and the rotor metallurgy is not all it should be. Some Tigers have suffered this problem when hot brakes are cooled by riding through a puddle. The second is that if the caliper cannot move easily, the brake pads may actually touch the disk in normal riding. this causes uneven and premature pad and rotor wear.
With floating disks, the calipers are generally solidly fixed and the disk rotor is mounted to a carrier with "bobbins" that are like usually fixed with circlips and allow the disk a small amount of lateral movement so that it can align with the caliper. This system is simple, light and works well IF the caliper and disk are closely aligned in the beginning. This system has an advantages of not really being liable to jamming up and is light. The disk rotor is not directly connenected to the hud and not liable to rotor warping due to mounting stresses. Both systems can be used at the same time.
You hear disks called "fully floating: and Ducati tend to advertise bikes with semi-floating disks. I think this is semantics from the marketing department. Disks are either solidly mounted or they float.
My opinion is that fixed calipers and floating rotors is the best option.
|
Linear Mode
