Do You Have Pulsing Brakes ???

[kballowe]

I just picked up a bike, and in the process of "going thru it".
 
The front brakes had a heavy vibration at speed, and a pulse pulse pulse pulse at low speed that would nearly compress the front forks.  Kinda like a motorcycle pogo stick.  Full lever, and no feedback.

Very annoying, to say the least.

The rotors were all nice and straight, and a micrometer confirmed that the thickness on both discs varied only by 0.002. 

These are "floating" rotors, so the next step was to spray all of the "buttons" with a little Fluid Film, and to let them sit for a few hours.  Used a tapered flat-blade screw driver (covered with duct tape) to insert into and turn each button back and forth and spray with brake cleaner.  There was a lot of grit and dirt and brake dust in there.

Wow, what a difference.  90% improvement.  Ima bead blast the rotors tomorrow, and put the pads on a piece of glass and some 100 grit paper.

Just a thought.... before ya run out and purchase new rotors - try a bit of cleaning

We now return you to your regularly-scheduled program.

[twowheeladdict]

 

Yep.  This type of thread shows up on forums for bikes with floating rotors.

[Bud]

Haven't used Fluid Film before but just looked it up. Wouldn't the brake cleaner take that off or did you use it first to get rid of any oxidation. I have the same problem with my Touring and have tried to clean but it only helped a bit. Very annoying!

[kballowe]

Haven't used Fluid Film before but just looked it up. Wouldn't the brake cleaner take that off or did you use it first to get rid of any oxidation. I have the same problem with my Touring and have tried to clean but it only helped a bit. Very annoying!

That Fluid Film was sitting on the work bench and I figured what the heck, it's good for corrosion.  Just in case.  Brake cleaner would have probably worked just fine by itself.  Maybe.

Sometimes the rotors get slick spots or uneven buildup of brake pad material and then ya can hand-sand the pad mating surface on the rotors with 220 grit paper.   Not enough to make them smooth - just rough them up, evenly.  Removing the rotors and bead-blasting them also works well. 

Fresh brake fluid also makes me happy.

If none of that works - then disassembling the calipers and a thorough cleaning might do it.

[chuck peterson]

With tonti t-t3-G5-vert brembo 08 calipers I've had a frozen piston on one side of the caliper that can create pulsing too

Rebuild or new

[yogidozer]

With tonti t-t3-G5-vert brembo 08 calipers I've had a frozen piston on one side of the caliper that can create pulsing too

Rebuild or new

Chuck, just got back from an early hike.
It's 12* out. My piston is frozen too 

[zebraranger]

Its a common issue with some Triumphs too, particularly the Triumph Trophy SE which I had the same problem with. I've found that spraying the bobbins with compressed air (150 PSI) every once in a while after a ride, and especially before washing the wheels has eliminated the problem. Fortunately I have a good compressor in the garage and it seems that when you wash the bike or when that brake dust gets wet while caked around the bobbins, it turns that dust into cement. The Griso's rotors and bobbins have remained problem free.

[tris]

I've read that Disc Thickness Variation (DTV) can be a big issue including floating discs on motorbikes, but I've no idea how true that is

http://blackshadow-uk.co.uk/Fitting.html

http://www.apecbraking.co.uk/getattachment/7c2582da-83bd-41be-8ecd-1ec73ea8ce8d/Understanding-Brake-Judder-and-Preventative-Steps.aspx

[Zoom Zoom]

I'm curious, which bike. the 1100 or the 1400? I had trouble with my EV's but not my Stelvio or 1400.

John Henry

[kballowe]

I'm curious, which bike. the 1100 or the 1400? I had trouble with my EV's but not my Stelvio or 1400.

John Henry

It's this 2009 CalVin
It looks so innocent, parked there.
 
.
.

[Perazzimx14]

You can also remove the buttons and clean and/or replace if work or Stick a 5/16th bolt with 2 washers through the hole tighten down a nut and spin the button as you spay in a little oil/wd40 then follow up with brake cleaner.

https://www.youtube.com/watch?v=MsNRaClpDXA

[guzzisteve]

The rotors are not as floating as you might think, more like semi-floating. Look at the high-end stuff and what it costs. Big deference between high-end and low-end Brembo.

[Bud]

Thanks for the input. I have shot the bobbins with air and it helped.Interesting about doing so before washing. I wash the bike 4 or 5 times a year so I think I'll clean the bobbins again and make sure to spay them with air before washing and hope for the best! I thnik I am going to take the pads out and give those calipers a good blast as well.

[blackbuell]

About a month ago my 2007 Norge very abruptly developed the type of severe pulsing described by the OP; had started checking out the costs of new rotors; was happy to see this thread. Yesterday I sprayed all brake parts with brake cleaner and checked out the bobbins; couldn't rotate them but was able to wiggle them all back-and-forth. I also sanded the pads. Due to winter weather I couldn't determine if problem was solved. The fact that the pulsing problem developed all at once makes me wonder if it is caused by a stuck caliper piston, as suggested by Chuck. I'll check out the pistons later this weekend. I seldom ride this bike very hard, and when I do push the pace a bit, I rely more on engine-braking to slow the bike than I do on the actual brakes; I doubt that I have ever over-heated the rotors.

I sure hope this approach works; new rotors for this bike are ridiculously costly. BTW, I did check the rotors with calipers; no obvious issue with width variation.

Jon

[Chuck in Indiana]

I seldom ride this bike very hard, and when I do push the pace a bit, I rely more on engine-braking to slow the bike than I do on the actual brakes; I doubt that I have ever over-heated the rotors.

You probably have discovered your problem. Gentle brake application tends to unevenly build up pad material on the rotors. Many times, a good hard stop will remove it. I used to have to do that fairly regularly to the Norge.