Floating Front Rotors: Yes or No?

cwcary · 11-17-2012, 06:34 AM

My service tech, a very knowledgeable fellow, tells me our bikes have floating front rotors. He "demonstrates" this by rotating (ever so slightly) each rotor in a forward/rearward motion. I remain unconvinced. Now I have read on here from another contributor that we have floating rotors. I'm still unconvinced.

To me a floating rotor is one mounted on a hub (or carrier) which allows it to expand radially and move (slightly) from side to side, i.e. from inside pad toward outside pad, which helps with rotor alignment vis-a-vis pads. In fact Brembo sells a set of floating rotors for our bikes, which I have been considering, not because I need them, but because I want them. They are mounted on a hub like I have described here and seen on other bikes.

This rotating disk phenomenon came up while my tech and I discussed an odd front end movement under slight braking, close to a stop, exactly like a loose steering head bearing. He offered the disk rotation as the reason for the odd movement which I had experienced, since the steering head bearing WNL.

So, do we have OEM floating disks or no?

Curtis

Taylor · 11-17-2012, 07:29 AM

Yes.

Up front 320mm dual floating rotors.

cwcary · 11-17-2012, 08:46 AM

Taylor,

If you don't mind, could you elaborate. I've seen tons of floating rotors, and none of them look like ours. On the other hand, I've seen many fixed rotors, which, look exactly like ours. So, please, tell me what makes ours "floating"?

Curtis

bmwian · 11-17-2012, 08:52 AM

I have full floating Brembo rotors and believe the stock ones are fixed.

My Brembo ones rattle.

Taylor · 11-17-2012, 08:57 AM

From google, and other people I've talked to they say the s1000rr are floating rotors, but I believe them to be semi-floating, if they were full on floating like the race bikes every bump you hit on the road would make the rotors noisy.

rThor234 · 11-17-2012, 11:48 AM

There's a difference between a solid one-piece rotor, ours which are designed to allow thermal expansion, and then a more 'full race' style where the rotor literally feels loose on the hat and is designed to see high heat before some of the slack is taken up. BMW (and I'm sure other manufacturers) use the same style 'floating' rotors on street cars. I know with the cars full floating rotors are noisy. I assume the same approach is taken for our bikes. Remember that some people still complain about vibrations- how would they feel about clunking rotors?

cwcary · 11-17-2012, 02:06 PM

Well guys,

I rode a ZX-14 for five (5) years and it came OEM with floating rotors and fixed calipers. These rotors were of the two piece design, which I believe encourages radial expansion to dissipate heat, and facilitate the rotor alignment with the fixed caliper. If there was rotor/caliper noise, I never heard it.

As for cars, BMW included, I believe they use fixed rotors and floating calipers, as did Harley-Davidson for many years. Here the rotor is fixed and only one piston/pad(s) move upon brake application, forcing the caliper to "move" over and contact the other side of the rotor with the other fixed pad(s) on that side of the rotor. I replaced this arrangement on my HD with Performance Machine, fixed calipers and HD floating rotors (an accessory at the time).

This floating caliper/fixed rotor is fine for street use, but, as I understand it is prone to "fade" making this setup less than ideal for the track. Also, I believe the OEM rotors on our bikes are prone to warping from lack of heat dissipation, and whatever the cause perhaps a set of Brembo hat rotors would alleviate this problem. Were mine to warp, I would replace with the two piece Brembos.

Curtis

viperclaw · 11-17-2012, 05:05 PM

If the caliper is "fixed" then the rotor is "floating".
Conversly: if the rotor is "fixed" the caliper is "floating".

S1000RR has fixed front calipers and a floating rear. That makes the front rotors floating and the rear fixed.

The front discs will move side to side. They don't move much and they don't need to. You don't really want them to or they will rattle quite a bit.

usrodeo4 · 11-17-2012, 10:04 PM

All I know is they work like a mother...last weekend was hauling the freight and came off the interstate at speed and forgot how downhill the exit was...with cars backed up at the light, so I had to really stand on the front brake at around 140+ mph...I was still doing about 70 or 80 when my rear wheel started getting awfully light...lol...nice brakes.

Godzilla · 11-18-2012, 10:49 AM

Quote:

Originally Posted by viperclaw

If the caliper is "fixed" then the rotor is "floating".
Conversly: if the rotor is "fixed" the caliper is "floating".

S1000RR has fixed front calipers and a floating rear. That makes the front rotors floating and the rear fixed.

The front discs will move side to side. They don't move much and they don't need to. You don't really want them to or they will rattle quite a bit.

Spot on.

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