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 Post subject: Disc Brake Question
PostPosted: Mon Mar 30, 2009 5:39 pm 
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Joined: Fri Apr 04, 2008 5:24 pm
Posts: 975
Location: South Yorkshire
I am currently running Hope Mono Mini's on my Dialledbikes SS and I am having a nightmare getting the front brake to not rub against the disc. No matter how much I adjust the caliper I am still getting rub and that horrible 'ching ching' noise! Has anyone got any tips or advice? The rear one is fine it's just the front one which is a pain. It is on a rigid carbon fork (RC31) and both front and rear discs are 160mm. I have heard that Shimano brakes are much better in the pad clearance department, is this the case? Please help and save my sanity!

Trevor.


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 Post subject:
PostPosted: Mon Mar 30, 2009 5:46 pm 
retrobike rider
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Joined: Tue Nov 11, 2008 12:28 pm
Posts: 4179
Location: rutland
im guessing you have used the paper thin washers to get the disc centered ?

loosen the bolts , hold the lever and see what fits best in the space between the caliper and mount

maybe the mount needs facing

i used to use rc31s and a mono mini ( sold the forks ) the squeal when braking gets annoying but no tinging


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 Post subject:
PostPosted: Mon Mar 30, 2009 5:47 pm 
Retro Guru

Joined: Wed Mar 07, 2007 10:08 pm
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Location: Newbury, Berks
Sounds like you could have a bent disc, or the pistons are too far out. Spin the wheel and look at the disc to see if it is warped then report back!


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 Post subject:
PostPosted: Mon Mar 30, 2009 8:41 pm 
Posh Mark
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Location: As far from the city as you can be ....
The way I have always done it is slightly loosen all mounting bolts and apply the brake. Then let go of the lever and spin and stop the wheel a couple of times.

After a couple of goes spin and stop the wheel and whilst holding the lever tighten the bolts.

Providing the rotor isn't bent and the pistons aren't sticking this has always worked for me.

Good luck :D


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 Post subject:
PostPosted: Mon Mar 30, 2009 10:16 pm 
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Location: Pennines / Manchester / Worcestershire
I've got the same problem on a Klein, rear disc. I've had Hayes and Avid Juicys on it, always with 9mm steel QR skewers (done up tight). Looking 'through' the caliper there's about 0.5 - 1mm clearance both sides with no rotor wobble and no rub whatsoever when you spin the wheel, however it still rubs intermittently above about 20mph when riding. Front is fine, never rubs. Further to what the others have suggested above, try using an elastic band to keep the lever pressed while you tighten up the caliper bolts. Also (I'm sure you've probably tried this) try resetting the pistons by pushing them into the caliper with a plastic tyre lever before centring the caliper.

On my Klein I've narrowed the rub down to either

i) the rotor resonating because of road-buzz and distorting enough to catch the pads
ii) the pads vibrating in the caliper (I've recently bought some EBC green organic pads to see if another brand's pads & spring make any difference)
iii) flex caused by the disc-mounting set-up on Kleins of this period - the mounting bracket is a cnc-ed piece which bolts onto the frame near the dropout. I've got a torque-arm fitted to mine which runs from the caliper mount bracket to the (redundant) cantilever boss, which is supposed to reduce stress at the dropout under heavy braking. I've had one Klein frame break a weld at the chainstay/dropout interface before now, taking no risks.

If you fix it, let us know how!


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 Post subject:
PostPosted: Mon Mar 30, 2009 10:41 pm 
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Location: Platsa, Messinias, Greece
One thing that you might want to check is that the outside circumference of the disc isn't touching the caliper body at any point.
I've had this happen with Magura Martas and had to loosen the disc mounting bolts and re-centre it.


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 Post subject:
PostPosted: Tue Mar 31, 2009 1:27 am 
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Posts: 2437
Location: Kent UK
Andy R wrote:
One thing that you might want to check is that the outside circumference of the disc isn't touching the caliper body at any point.
I've had this happen with Magura Martas and had to loosen the disc mounting bolts and re-centre it.


I had this problem on a Hope Mini (before the monos came out) and I ended up taking 0.5mm off the top of the wavy bits of the disc.


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 Post subject:
PostPosted: Tue Mar 31, 2009 9:13 am 
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Joined: Fri Apr 04, 2008 5:24 pm
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Location: South Yorkshire
Thanks for the tips guys, will keep trying! With regards to the disc, it is brand new so should not be warped and the PACE forks are NOS so again they should not be the problem. I never got any of the paper thin spacers described but did get 2 normal width washers? Will undo the disc bolts and play around with all the mounting bolts and get back to you.

Trevor.


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 Post subject:
PostPosted: Tue Mar 31, 2009 10:28 am 
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Location: Pennines / Manchester / Worcestershire
You could always try some of these:
click - I've got some (but they didn't work :lol: ), I can let you have a couple though if you send me a SAE.


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 Post subject:
PostPosted: Tue Mar 31, 2009 3:39 pm 
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Joined: Fri Apr 04, 2008 5:24 pm
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Location: South Yorkshire
Think the disc might be warped after all. It is only catching at one point during its rotation with clear side to side movement. I am going to contact Chain Reaction about getting it replaced.


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