Hi guys, Just picked up an 07' sm610 and am really loving it so far. I have some concerns about my front brake rotor though. When I come to a stop I experience low speed judder. Are these rotors meant to be fully floating, or should they be relatively fixed. I am hoping it's a seized floating disc and not a warped one. Also, what's the deal with this grey insert with its own mini c-clamp? There is only on on the entire setup and I can't seem to figure out what's its purpose is. Cheers!
The disk should be floating. The grey cylinder you speak of is probably the magnet used for the speedo.
The insert is a magnet that is picked up by the speedo sensor in the caliper bracket. The rotor is floated, but there are wave springs that keep pressure on the bobbins to keep it centered and to keep it from rattling. I experienced some similar "pulsing" on the front brake. I measured the rotor for warpage and runout, nothing. I swapped the pads out for EBC sintered HH pads, and it went away immediately. The brake feel was also much improved, with less lever pressure required, but not overly grabby. Just don't grab a handful in a curve.
How does your post show up as 11:44am yesterday, and before my post, when you posted at 1:22pm today?
Because magic :P My post was actually written and sent before yours but had to be admin checked before users could see it. (Not trying to take credit or anything)
RDTCU, how much pressure do the wave springs apply? Should I be able to move the disk, with my fingers if I apply enough force? Late response, I have been really busy with work.
They're pretty tight and there are a lot of them, but I can get a tiny bit of wiggle by hand. They shouldn't walk all over the place, they are just floated to prevent warpage from misalignment and thermal expansion.
I just noticed this on my setup when switching to the enduro setup. I have lost a couple of the rubber doughnuts in mine. I don't see the wavy springs that RDTCU is refering to?
Some older rotors had O-rings, the newer ones use wave springs. Some other bikes use Belleville washers, some have wire springs captured in a groove in the middle of the bobbin. All they are doing is keeping the rotor from flopping around and keeping it centered. This also makes your brakes more responsive because the rotor hasn't spread your pads apart and you need less lever travel to engage the brakes. Some bikes don't have any of these things and the rotors can just flop and rattle once they're worn in or hot.
