Thursday, May 22, 2014

Full Floating Brake Rotor Conversion [konversi cakram menjadi full floating]

This seemed to be the most convenient method to refresh my “Modders Anonymous” renewal notice that came in the mail the other day.

There are basically 3 types of brake rotors for motorcycles; fixed, semi-floating and full floating. Our stock, front, semi-floating brake rotor is essentially a 3-piece assembly consisting of a center aluminum carrier, the outer stainless steel disc and 8 buttons that hold them together. The rear brake disc is an example of a fixed rotor.

Here's the stock front rotor.

The front rotor is disassembled by drilling the back side of each button, similar to drilling out a pop or blind rivet. You would not be inaccurate to think of the disc “riveted” to the carrier with these buttons.

After drilling 7 buttons, the carrier will slip away from the disc. Here’s the remaining, intact button assembly showing (top to bottom) the peened over flange, large diameter steel retaining washer, anti-rattle wavy washer and outer flange of the button.

Left to Right – large washer, wavy washer and what’s left of the stock button.

These are called semi-floating rotors because the wavy washer exerts pressure against the disc preventing rattle. The disc can still move side to side or float, which you can do with your thumb, but it takes some force. The ability of the rotor to float side to side compensates for heat distortion of the disc, a frozen pad, etc., while not compromising the front braking system.

Hear that hissing sound when your front wheel is off the ground and you spin it by hand? That’s the disc in constant contact, although slight, with the pads. This drag, plus bearing friction, prevent the wheel from revolving more than a couple times. A full floating rotor has buttons without a wavy washer and no interference fit when assembled. The disc moves side to side between the pads, up to about 1.5 mm max at the very edge of the disc, without moving them or even coming in contact so the friction between the two (brakes not applied) is eliminated. Consequently, heat build-up is virtually eliminated to help reduce potential fade.

STM, an Italian component manufacturer, has been making full floating buttons for some time and I purchased a set designed for the 675’s 4.0 mm thick brake disc.

Left to right, hard anodized STM button, retaining washer and circlip.

I stripped the gold anodize from the stock carrier and polished them to match the appearance of my wheels.

The components were reassembled, wheel checked for balance and I’m back on the road…

…with just a touch of red paint to detail the inside of the button!

Full floating rotors will produce a slight rattle when going over bumps at speeds less than about 5 mph. At higher speeds, centrifugal force takes over eliminating any rattle.

This is a mod I’ve done to many Japanese sportbikes in the past, primarily Suzuki’s and Yamaha’s, but I’ve not seen anyone modify the 675’s rotors before. Brembo sells full floating rotor assemblies in pairs with cast iron discs (usually better heat dissapation than stainless steel) for most sportbikes, but at a cost nearing $900. My solution has worked for years with excellent results. STM buttons usually retail for less than $200.

Reduced operating temperature? Yes
Better braking performance? Yes, although not discernable on the street.
Virtual elimination of friction between pads and disc? Yes.
Slightly lighter? Yes, VERY slight!
Unique? Very.
Makes a really cool, race bike rattle sound when you push the bike around in the parking lot? Yes.

And after an hour on the Bridgeport, I may have another surprise! Stay tuned.


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