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PostPosted: 24 May 2009 20:27 
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The Nagged Hubby
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it's a flat as a witches booby and the wheel is well in run out specs!
The disc is free to move in the bobbins and all the springs are free too!
It came on in Scotland after about a thousand miles into the trip.
The milage on the bike is 5 grandish.

I can not feel any play in the headstock and it is very free.
I removed the bobbins yesterday and this morning it felt better on the lever and stopped ok but it soon returned as in the bike comes to a juddering stop.

Any ideas or notions?

Nate.


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PostPosted: 24 May 2009 20:35 
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I have same problem now.... but realised front bearings knackered.. so replaced.. result improved the juddering but not totally cured, also forks are soft as new seals needed, i think this may also effect it to some degree but not wholly sure..(these are just ideas).. have you renewed front brake pads for those extra spec sport HH pads.. that need loads of heat to work in the right way?.. i have these same pads and am going to change them as thery seem to "grab" the front wheel... as not enough heat in them with out the constant heavy breaking required... and lastly .. yup.. a warped disc is highly poss.. and peob the way im gonna have to go after ive corrected the other probs... .. sorry if its not real help but its just from my recent experiences.. when in doubt ask the Tubbs.. or Maz..IMO :yt:

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PostPosted: 24 May 2009 20:37 
Does any part of your disc look like this

http://i46.photobucket.com/albums/f126/ ... disc02.jpg


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PostPosted: 24 May 2009 20:47 
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I also had that studdering brake when I got the bike new. I cleaned/sanded the rotor and replaced OEM pads with EBC HH. After that I never had any problems with that again. Other pads might work as well, but the stock pads apparently seem to leave uneven deposits on the rotor.

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PostPosted: 24 May 2009 22:15 
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The Nagged Hubby
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longdog_cymru wrote:
Does any part of your disc look like this

http://i46.photobucket.com/albums/f126/ ... disc02.jpg


No dude and thanks.

The pads are from maz and they were working great. There seems to be no deposits as the OEM parts they replaced.
I honestly believe the disc is not be warped, the only disc I bent was on a Yam years ago and you could see it was way out but it felt the same as this now. I managed to straighten the Yam disc back to perfect opperation, I can not even see enough run out to attempt anything with this one!

I could try the old pads n' see what the difference is :idea:

N.


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PostPosted: 24 May 2009 22:47 
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proff. patpending
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Stock pads are renowned for leaving deposits on the disc.

Do as Herr Gunter says, sand/steel wool the disc with brake cleaner.

The brake caliper is sensitive to changes in disc thickness
The brake pads are sensitive to changes in frictional coefficient of the disc

The thickness will not have changed (leave that for vented discs), you will just have transferred some pad material to the disc by keeping the brake on whilst the disc is hot, e.g. when you stop at the end of a motorway slip road with the brake on.

Trawl the old forum, I found a great link, and Herr Gunter provided other info of use...

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PostPosted: 24 May 2009 22:52 
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The Nagged Hubby
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Cheers Pash and Herr gunter, I will try your recomendations tomorrow and report back :D

N.


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PostPosted: 25 May 2009 15:51 
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The Nagged Hubby
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Hmmm, sanded the disc and loads of black came off but it still does it.
I can see the forks nodding back and forth when slow enough down by the spindle.

The Mrs and I had the pleasure of meeting Softly today, turns out he only lives down the road!
He suggested the head stock bearings, got me thinking as I have hit some good holes and bumps recently.
Think a trip to Maz stores is on the cards!

Nate.


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PostPosted: 25 May 2009 16:02 
you could replace brake fluid and make sure the wheel is balanced,I had that pulsing once on an RC30 and I went through it all,turned out to be wheel balance,could be same with you


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PostPosted: 25 May 2009 17:13 
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The Nagged Hubby
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Suppose I could jack it up and get the pads well off the disc n' spin the wheel and see if it wants to stop in the same place!

Will try. Ta.

N.


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PostPosted: 25 May 2009 22:47 
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proff. patpending
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Try some brake cleaner

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PostPosted: 26 May 2009 17:48 
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Nate wrote:
Hmmm, sanded the disc and loads of black came off but it still does it.
I can see the forks nodding back and forth when slow enough down by the spindle.

The Mrs and I had the pleasure of meeting Softly today, turns out he only lives down the road!
He suggested the head stock bearings, got me thinking as I have hit some good holes and bumps recently.
Think a trip to Maz stores is on the cards!

Nate.

Hmmmm gets me thinking!! gonna have to look at mine then also.. actually will get tubbs to have a shufty at them on saturday when he does fork seals etc..

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PostPosted: 26 May 2009 19:05 
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The Nagged Hubby
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I took another look at it tonight after work. I'm convinced it is the disc.
I marker pened the disc and found where it was rubbing on the pads. Not quite half the circumfrance was rubbing.
Removing a bolt and spacer I noticed the steel washer was not flat. With the disc showing very little warp I flatted the washer on an oil stone rotating it keep things even. I was hoping this would allow the pin to just pull the disc in a few thou more. I put some chain wax on the washer to prevent it rusting and torqued it up.
It resulted in the disc rubbing less on the pad!
So I did the others either side of that one and sure enough it is now just scraping the pad all the way around.

A road test will tell for sure, it would be nice if it is that easy!!
Fingers crossed!

N.


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PostPosted: 26 May 2009 20:39 
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Current ride: CB1300, Z750, R1200
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Nate wrote:
I noticed the steel washer was not flat.

You might want to read this.

In essence: under some circumstances the shouldered screws are not exactly centered in the washer's bore (because of the undercut at the beginning of the thread), so that washers, slipping into the undercut, are partially pushed into the rim's bore, while other parts of the shoulder are inside the washer's bore instead of sitting on it. Torqueing the fastener warps the washer which in sequence makes the floater cant and get jammed into the rotor, losing all required clearance.

I hope I looked up the technical terms correctly.

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PostPosted: 26 May 2009 21:46 
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Nate, how exactly are you checking the disc. to be accurate you need to use vernier calipres for thickness and a dti gauge with mount, mounted securly to the lower fork leg (not sat on the ground). if need be i can probably find all of the above.


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