Floating rotors?

[wkboardr]

I have read several topics about the brakes, but I have never heard anything about this one. I was cleaning my bike and when I went to wipe off my rotors, I noticed they moved a bit. I then grabbed it with my hand and put a little more pressure and could move them side to side about 1/4" or less over all. I went into the local dealer and check the other 06' that has never been ridden and it was very similar. There also happened to be a Hyabusa in the lot and they have similar floating rotors, I checked the same way for them and they didn't budge at all. Is it normal to have that much play?

PS It is actually the same on my rocket 3, alot of movement overall.

[Spendthrift]

Apparently it is.

[Avi8or]

You have to allow for expansion of the rotor when it heats up under braking otherwise it may distort.
Apparently race bikes rotors really rattle about.

[Geof3]

totally normal... It's also to alleviate and alignment issues... No need to true the rotor if it floats.

[Snox49x]

Mine do the same thing. Would this cause a clunk to be felt through the bars when braking hard?

[Geof3]

On 2006-06-25 13:35, Snox49x wrote:
Mine do the same thing. Would this cause a clunk to be felt through the bars when braking hard?

No, the clunk is your head bearing being loose. Common for the new bikes. Needs to be tightened up a bit...

If you hear a tiny click, this is the rotors shifting a bit.

All the latest brakes have floating disks...

[Skydakine]

"Tech Talk

What is Full-Floating?

What is Full-Floating?Full floating rotors, such as were originally conceived, were designed to reduce the tendency towards thermal stress induced distortion due to uneven thermal expansion under load. Prior to the introduction (by Brembo) of this design, brake rotors in the motorcycle industry were simply round discs bolted solidly to the wheel. You may remember if you've been around long enough, the rotors on the early CB750 and Z-1's were nearly 7mm thick and weighed accordingly. This was in effort to keep them from warping. Now days, the only road bikes coming through with solid mount (front) brakes are the Cruisers and budget bikes.

Today's Sportbikes abound with trick features and hardware in every nook and cranny. Brakes too. The brake rotors on them work remarkably well considering their mass-produced (read: stamped) manufacturing process. These are technically semi-floaters as the outer SS blade is nearly bolted solid to the carrier via the stamped stainless steel rivets.

True full-floaters move on the carriers, this allows them to self-center in the caliper for reduced brake drag and "float" unimpeded for unrestricted expansion and contraction during repeated thermal cycling. The only serious down side is a bit of rattle that reminds you these are indeed full-floaters.

Does all this guarantee they won't distort under severe duty conditions? No, unfortunately, there's precious few guarantee's these days. But they do perform as advertised in improving overall braking performance while significantly reducing that distortion tendency.

BTW: All Superbikes, GP machines and the like unanimously have full-floating brake rotors."

This is from http://www.ferodobraketech.com/tech/floating.html


"All metals "grow" when heated. The diameter of cast iron brake discs can increase as much as 2mm (0.080 inch) at elevated braking temperatures. When the disc is radially restrained from growing (as in all one-piece discs) the friction plates are forced into a cone shape as temperature increases, adversely effecting both temperature and pressure distribution within the pads and the feel of the pedal."

This quote is from Shop-Tech Brake Products. Even though the site is automotive based, the theory of floating brake rotors applies to motorcycles as well.

[ This message was edited by: Skydakine on 2006-06-25 17:33 ]

[R100Pilot]

It's not just a matter of float. You can actually flex the Triumph rotors. Same thing on the new Daytonas. You can wiggle the thing side to side and see it bend.

I dunno - as long as the thing stops, I'm happy.

[wkboardr]

I appreciatte the education, although the floating rotor on the Hyabusa was much tighter and built very similiar with much less play.

Based on the concept, the looser they are, the better they work. Short of coming off, of course!