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Discussion Starter · #1 ·
Hi,
I'm running 185mm Avid disc in the front and it resonates and rubs on the pads slightly causing an annoying squeal (not to mention premature pad wear). The brakes have massive stopping ability and I am thinking of switching to a smaller diameter disc which should in theory be less prone to resonance. The other alternative is to stick with the same diameter but find a disc which is more rigid. Anyone been down this path before?

Thanks
Splint
 

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Old man on a bike
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If it rubs might be a caliper alignment or rotor truing issue also contributing to the noise...but which brakes?
 

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Discussion Starter · #3 ·
Thanks,

the brakes are Juicy 5. I guess the root cause is allignment, warped disc or failure of the pistons to retract sufficiently. Probably no value in going for a smaller disc if that's the case. I'll look into it futher.

Splint
 

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irideablackbike
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Rotor resonance

I've been wondering about this for a while, but people tend to put a rubber damper on tennis rackets to prevent vibration reaching the hand and to deaden the weave of the racket. I'm wondering if you put something similar on the spokes of the rotor like connecting them with tape or something if that would help. Just a thought.
 

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achiever
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I have a 185 G3 with BB7's that howls like mad. It drives me absolutely insane. I have tried sanding the pads, realigning the caliper and cleaning the rotor. I can get a ride or two but the noise always comes back. I think the problem is that the pads are grabbing too close to the spokes of the rotor. I shimmed the caliper up last night with some washers to pull it away from the spokes. Hopefully this will work.
 

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Discussion Starter · #6 ·
I backed off the mounting bolts just enough for the caliper to move then applied the brakes a few times to let it find its' natural position then held the brakes on and tightened the bolts. Prior to adjustment I could see a clear gap between the inboard pad and the disc and barely any gap at all on the outboard side. Now the brakes have an even gap and they tend to really grab because the pad contact is no longer staged. There's now no noise while I spin the wheel or push the bike around, haven't had a chance to ride yet but I'll report back after I've had a few rides to see if this is a long term fix.

Redwarrior, I'm not familiar with your brake setup (new to the MTB scene). Possibly the seals in your pistons are starting to get old and hard and don't have sufficient ability to properly pull the pads back off the disc when the brakes are released. Also if there is some type of spring system to assist pad retraction you bay be able to stretch/bend the spring to make pad retraction more effective.

Cheers
Splint
 

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Old man on a bike
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Splint said:
I backed off the mounting bolts just enough for the caliper to move then applied the brakes a few times to let it find its' natural position then held the brakes on and tightened the bolts. Prior to adjustment I could see a clear gap between the inboard pad and the disc and barely any gap at all on the outboard side. Now the brakes have an even gap and they tend to really grab because the pad contact is no longer staged. There's now no noise while I spin the wheel or push the bike around, haven't had a chance to ride yet but I'll report back after I've had a few rides to see if this is a long term fix.

Redwarrior, I'm not familiar with your brake setup (new to the MTB scene). Possibly the seals in your pistons are starting to get old and hard and don't have sufficient ability to properly pull the pads back off the disc when the brakes are released. Also if there is some type of spring system to assist pad retraction you bay be able to stretch/bend the spring to make pad retraction more effective.

Cheers
Splint
Checking alignment is a good thing, you've probably solved your problem. Who set up the brakes initially?
 

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Discussion Starter · #8 ·
irideablackbike said:
I've been wondering about this for a while, but people tend to put a rubber damper on tennis rackets to prevent vibration reaching the hand and to deaden the weave of the racket. I'm wondering if you put something similar on the spokes of the rotor like connecting them with tape or something if that would help. Just a thought.
Mass dampers can be quiet effective at shifting the vibration to a frequency where it either can't be detected or is peaking at a point beyond the normal operating range of the equipment. It may be easier and more aesthetic to simply try a disc with a different mass or rigidity. Certainly no harm in experimenting with a home made mass damper, provided it doesn't pose a threat of coming adrift and causing the wheel to jam up and lock.

Splint
 

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Discussion Starter · #9 ·
Bikinfoolferlife said:
Who set up the brakes initially?
The Australian Yeti dealer. They were probably set up correctly in the first place but for various reasons one pad can wear faster than its' mate. The most probable cause is a slightly sticky piston. I don't think I can point the finger at anyone, it's just one of those things, sort it out and keep on riding.
 

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Old man on a bike
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Splint said:
The Australian Yeti dealer. They were probably set up correctly in the first place but for various reasons one pad can wear faster than its' mate. The most probable cause is a slightly sticky piston. I don't think I can point the finger at anyone, it's just one of those things, sort it out and keep on riding.
Glad you're learning, just wondering what/when of things since you weren't very specific about setup/maintenance/troubleshooting kinda stuff...
 

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achiever
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I think I solved the problem on my BB7's. I ditched the clean sweep rotor and went back to the roundagon, ebc organic pads and shimmed the caliper up abut a millimeter. Very little squeal so far.
 

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I am starting to believe some of the howling issues may be related to the wheels/spoke tenstions.

I have 2 sets of I9 wheels, one with louise FR, one w gustavs, and both howl like mad. I have faced, aligned, replaced, etc. Howling persists.

While I was doing something on one set of the I9s I put a pair of "standard" wheels on, and all of a sudden my howling stopped. Went back to the I9 and noise was back.

Am thinking about things I can use to reduce the vibrations now (silly putty on spoke crossings anyone?)
 
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