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PostPosted: Fri Mar 23, 2012 11:30 am 
aka Leo Swayer
aka Leo Swayer
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Joined: Wed Jun 18, 2008 7:15 pm
Posts: 6365
Location: Wales.UK
ARRRRGGGHHHH!!!!!!
So, i've lengthened the hoses on my Shimano XT disc brakes and changed the rotors to Hope floating ones.
Bled the brakes, cleaned the discs with brake cleaner, to be on the safe side, and taken the glaze off the pads with some roughish wet and dry.
Prior to all this the brakes worked perfectly and quietly.
Now they both squeal like "pigs on honeymoon" :x
Next thing i was going to try was deglazing the discs?
Calipers are square to the discs.

What am i missing folks? :roll:


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PostPosted: Fri Mar 23, 2012 12:54 pm 
Old School Grand Master
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Location: Antwerp, Belgium
Squealing is usually the result of grease on the pads or rotors. No, really !

Take the pads out and sand them again. While the pads are out, clean the rotors with degreaser (or vinegar, it's just as good and a lot cheaper).
Don't forget that after cleaning and sanding, the brakes will need the usual bedding-in routine (either prolonged riding with the brakes applied or 30-ish successive stops from 20-ish MPH) before they start working properly.

However sometimes it's just the nature of that particular brake setup, and no amount of cleaning will help.
In that case, I suggest filing off the leading and trailing edges of the pads at a 45° angle. (these aren't bike pads, but they should give you an idea)
I used to do that on my motorcycles and mopeds, and it was a sure way to stop any squealing. Worked on my Bulls' original Formula brakes too.
Don't worry about the (small) amount of contact surface you'll lose, you'll have plenty of braking power left.

It doesn't hurt to do everything at once. File off the edges, sand the braking surface and clean the rotors.

EDIT : Considering you changed the rotors, it just might be that the pads and new rotors are a combination that's more likely to squeal.
I think I have the same rotors (Hope Saw, right?) on my Bulls, and they're silent in combination with whatever pads came with my Formula RX20 brakes.
Still, filing off the edges will probably solve it in your case.


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PostPosted: Fri Mar 23, 2012 3:18 pm 
aka Leo Swayer
aka Leo Swayer
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I'll try heating them/bedding in, if that doesn't fix it i'll get the file out :wink:


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PostPosted: Fri Mar 23, 2012 4:58 pm 
Posh Mark
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Location: As far from the city as you can be ....
I found my Hope floating rotors to be far more prone to squealing that the Magura rotors that replace them.

I have also found that the tightness of the caliper bolts to be a previous culprit :evil:


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PostPosted: Fri Mar 23, 2012 8:03 pm 
Gold Trader
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This has always worked for me.
Whilst out on a ride push some mud into the gap between the rotor and calliper. Force it in and pump your brakes whilst riding. This scores the pads and disks and gets rid of any grease build up. Don't take it to extreme but I've done this on XTR, Hope and XT disc's and has sorted it 1st time (that's only if you lines them up properly though)


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PostPosted: Sat Mar 24, 2012 12:15 pm 
Gold Trader
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Location: Odense, Denmark
Muc-off disc brake cleaner stopped my sons' (yes, plural) Shimano brakes from squealing.... so it's worth a try.

It's good stuff - you are actually supposed to get it on the pads and pistons too..... Braking is reduced a bit until you've burnt back through the residue though.


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PostPosted: Sun Apr 01, 2012 12:53 pm 
aka Leo Swayer
aka Leo Swayer
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Joined: Wed Jun 18, 2008 7:15 pm
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Location: Wales.UK
Would air in the system have anything to do with the squealling?
Brakes are still a bit spongey :?


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PostPosted: Sun Apr 01, 2012 1:30 pm 
Gold Trader / rb Rider / Special
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Shouldnt affect it. What have you tried?


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PostPosted: Sun Apr 01, 2012 1:47 pm 
aka Leo Swayer
aka Leo Swayer
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Joined: Wed Jun 18, 2008 7:15 pm
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Location: Wales.UK
Everything :D
I think the discs need deglazing, i think you can get paste to do it with, i'm looking into it :wink:


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PostPosted: Sun Apr 01, 2012 1:49 pm 
Retro Guru

Joined: Mon Aug 21, 2006 12:10 pm
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Location: High Peak
Try braking less. HTH.


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