Floating rotors pulsing

[double_entendre]

2005 FJR1300

I bought a used set of floating rotors from a guy on the FJR Forum. They work great....mostly. They don't pulse if I'm slowing down, but if I come all the way to a stop the front end pulses pretty significantly from about 15mph to zero.

Any thoughts on what that might be from? I cleaned the hell out of the rotors and put new pads on to no effect.

Thoughts?

Thanks!

Rancho

[gvthnks]

floating rotors can warp beyond their float capability. Why did the seller get rid of them in the first place?

The other thing I would check is that the mounting flange under the rotor is clean and doesn't have anything causing runout on one or both rotors.

You can isolate which side it is causing problems by introducing a little air in one caliper, then the other and testing on a closed course......

Bleed each side after the test so that side works again.

[bisbonian]

Some of the guys with newer Guzzi's are finding that the buttons that make the rotor float get stuck and need to be freed up.

Fixed have run the gamut from spraying on some brake clean and working the buttons to going after them with a hammer (not sure how that works) with varying degrees of success.

[Boon Booni]

Here's an interesting article that says that pulsing brakes isn't caused by warped rotors and in fact rotors don't actually warp in the way people imply.

LINK

[RecycledRS]

Very good artical. I learned something.

[P B G]

Yes, but if I remember the article properly, its about car rotors. Which are thicker parts in general and often constructed of two surfaces separated by fins for added thickness, rigidity, and heat dissipation. Also I think motorcycle disks are harder than those on cars, sort of want to check that now.

Motorcycle rotors occasionally wear in a wavy pattern across the disc face.

I don't know if these factors negate the article.

[fast4d]

with the front wheel off the ground does the wheel rotate freely? or does it stop soon as you let go?

try cleaning all the buttons with brake cleaner or denatured alcohol first.

in the past, I've done the following with success. note that you'll heard some noise from your rotors at low speeds.

quote:

I sharpened the tip of a flat tip screwdriver, and used it to flatten the "fringed" spring washers found on the inside of the rotors' "semi-floating" rivets/buttons.

The key is just to flatten the convex fringed spring washers, without bending the fringes upward (ie: don't make them concave) . The edges of the washers shouldn't be more than 1mm off the surface of the rotor when you're done.

It's easiest to get underneath the edge of one of the spring washer's fringed edges by starting in the gap between the rotor and carrier. Once the screwdriver tip (or other equivalent sharp, narrow tipped chisel) is slid under the fringe, only lift it slightly to bend the fringe just barely away from the rotor.

Instead of having to work the sharp tip under each fringe of the washers, slide the tip sideways from one fringe to the next.

After the above procedure, the rivets should all be loose, and the flattened spring washers should spin on the rivet with only a light push with your finger. Grasp the assembly by the carrier, shake it, and the rotor should rattle a bit.

I sprayed the rotor rivets with brake cleaner when I was done, and the pressure of the spray can's stream was actually enough to spin the spring washers on the rivets!

The only even slightly negative result of this mod is the increased noise. With normal or even heavy braking, the difference in braking volume isn't noticeable, but ride over a pothole at low speed (without the brake on), and you'll hear the rotors jingle a bit. The tradeoff is well worth it."

[double_entendre]

Interesting thoughts gang and the article Boon Booni--I too wonder if it applies to motorcycles.

I appreciate it. I think I'm going to start by just going at the rotors with some kind of emery cloth or some such to try to give them a clean surface. If that doesn't work, I'll try to figure out which one is the bad one (thanks for the tip gvthnks) and then focus my efforts. The previous owner said he had no issues, so I have no idea why I'm having problems.

I love this place.

Rancho