Heavy Braking Shudder

[cyclesailor]

My `02 Sprint ST shudders under heavy braking,the faring and mirrors vibrate untill I release the front brakes.
The brake pads were replaced last spring. The rotors have .003-.004 TIR and visually look OK and are in tolerance of minimum thickness. The steering head bearings are to specs. and wheel bearings seem alright.
Light to moderate braking no vibration or shuddering. The bike does stop straight and true under light to heavy braking.

Suggestions,Help!

[dolson]

Try hosing down the bobbins that allow the rotor to move around some, you might have one or two that are sticking.

[Sticks]

Had similar issue I used my compressor to blow out some of the grit and then washed them with soap and water with a tooth brush.

OnD uses some thing to spin them to get them to float a little better I looked for his post a couple of months back but got side tracked

Sticks

[Gatorman]

I use a spray of brake cleaner and rotate them a bit

[RexxyPup]

Hi,

find an allen key that is a little smaller than the hole in a bobbin, wrap some gaffer tape around it until it fits with a little persuasion and use that to spin the bobbins as you spray brake and contact cleaner in it

Rexx

[steventhechef]

all good advice. The bobbins get gummed up and it is part of my regular service.

[DaveM]

I use Motul brake cleaner

DaveM

[321Go]

Originally Posted by steventhechef

all good advice. The bobbins get gummed up and it is part of my regular service.

idiot question time. What's a bobbin? Feels like mine need looking at if shuddering under front braking is a symptom. Thx.

[DaveM]

Originally Posted by 321Go

idiot question time. What's a bobbin? Feels like mine need looking at if shuddering under front braking is a symptom. Thx.

321Go

Not an idiot question, it is not a technical term (well I don't think it is).

The bobbins are the circular thingamajigs on the rotor that connect it to the rotor frame doohicky.

On the Sprint there are about 10 of them and they are approximately 20mm in diameter with about an 8mm hole in the centre.

They allow the discs to move about a bit. They are meant to be free but get gummed up with brake dust and road crap.
When they cannot allow movement they can cause the vibration previously described through the bars.

This is my non technical explanation, the only kind I know how

DaveM

[321Go]

Thx a lot. I assume that any brake cleaner should be applied sparingly to each 'bobbin' whilst loosening up.
A job for this afternoon i think. Cheers DaveM.