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Discussion Starter · #1 ·
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!
 

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

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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
 

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Spin the bobbin

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
 

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

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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:p

DaveM:cool:
 

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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. :D
 

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i spray brake cleaner on an old tooth brush, then scrub around them. that way you dont get overspray on the wheels or paint. plus you can heat and bend a tooth brush to reach the inside of the "bobbins" as you all call them :D "oral reach" i think is the one I use LOL
 

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Check the tightness of your caliper bolts. If these are loose or have stripped the thread you will get vibration. They will also become dangerous.

One of my threads pulled out (sheared the root of the thread) and I experienced exactly what you are saying - i.e. I noticed the vibration through the mirror. I had to recoil my caliper to fix the thread and it was fine afterwards.
 

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I just tried the spinning thing. I put a 1.5 in bolt through the bobbin snugged it up with a nut and washer and spun it with a variable speed drill (not fast). It loosened the bobbin up considerably. I can spin it with my fingers now. I think I'll do it with all of them.

Interesting the service manual says nothing about bobbins or how to remove or maintain them.

It appears the rotors are SS the bobbins are SS but the carrier is steel and prone to rust. Rust has to be removed mechanically not with spray
 

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.. do you get a pulsing feeling through the brake lever?

I've had the vibrating front brake thing happen to me twice now.

1st time I could feel the pulsing through the brake lever and it turned out I had warped front rotors which were replaced under warranty.

A couple of months ago I started to get similar symptoms but no pulsing through the lever this time.I gave the front rotors a good scuff up with 240 grit paper and they are now much better - so probably some crap on them.

Grant:cool:
 

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I just tried the spinning thing. I put a 1.5 in bolt through the bobbin snugged it up with a nut and washer and spun it with a variable speed drill (not fast). It loosened the bobbin up considerably. I can spin it with my fingers now. I think I'll do it with all of them.

Interesting the service manual says nothing about bobbins or how to remove or maintain them.

It appears the rotors are SS the bobbins are SS but the carrier is steel and prone to rust. Rust has to be removed mechanically not with spray
I have had the vibration/"pogo stick" stopping syndrome twice now. The first time the rotors were changed under warranty but second time round no such luck. I tried cleaning the bobbins with brake cleaner and then turps using a paint brush to try and work the liquid into the space behind. Before I started the bobbins were jammed tight and I managed to free them up so that I could turn them with my finger. I think there was a slight improvement with the shuddering. My question is: how loose should the bobbins be ie should they actually spin freely or just be loose enough to turn by finger. I don't want to pay $500 + for new rotors!
 

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The bobbins are spring loaded so the won't spin free. Fount this elsewhere.

This brake conversion uses 2 piece brake discs, one of the major benefits of a 2 piece brake disc is its ability to allow the disc ring to float freely on the bell housing. On the race track it is easy to design a disc with this functionality; however a clanking loose disc ring driven on the street quickly looses its appeal. To overcome this ECS employ the use of a disc bobbin and conical spring washer. This allows the disc ring to float freely on the hat while spring tension from the washers holds the disc ring snuggly in place. The result is a true floating disc with out the ordinary side effects of rotor clank produced my high performance 2 piece track discs.
 

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Cleaned mine up as recommended. No more vibes under braking.
The bobbins were solid. Triumph should advise making them part of your maintenance checks methinks.
I'm glad i asked! Thanks for the advice :D
 

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I need to do this as well. Funny though it's only started doing it since i changed the front brake pads the other day. Have checked the bobbins and a few of them are sticky so will give it a go @ weeekend
 

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Thanks for PM from SteveTheChef.

Tried this today on my 2006 Sprint ST to alleviate the brake shudder problemm. Has worked about 95% ... there is still a little bit of shudder left there, so maybe I need to clean the bobins again. But it is heaps better than it was, and the braking efficiency seems to be a lot better.
Will definitely have this on my normal maintenance schedule.
The brake cleaner spray can was $5AUS. A lot better than forking out $800AUS on a new set of rotors!
 
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