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Discussion Starter · #1 ·
At first I was worried that I wouldn't be able to get my wheels to spin pad rub free, but I actually now have a business cards' worth of space between pad and rotor both front and back and the wheels spin freely. :thumbsup: The front brake is silent but the back brake...:madman: :madmax:

I've been riding silent BB7s for years. I know what silent brakes are supposed to sound like...silent! The rear has this "hmmmmmm" the second pad touches rotor. I've tried:

Aligning and re-aligning the calipers so the pads contact the rotor evenly front/back side/side up/down. I loosen the caliper bolts, spin the rear wheel and slam on the lever, the wheel stops abruptly...I do this figuring the caliper will be jolted into the correct position, you know, forcing the Tri-Align system to work as advertised. This is after doing the loosen and eyeball for proper clearance then gently tightening in previous attempts. None of this works to lessen the howl but it did to get the wheel to spin freely. Too bad I couldn't have solved both problems at once!

I thought maybe it's got something to do with the pads in the rear and the G3 so I put on a another wheel with a Clean Sweep and it made the same noise. I put a tiny washer under the calipers in back to raise it a tiny bit figuring the pads would then contact the rotor just enough maybe to defeat whatever oscillation is happening. Nada.

I switched the pads side to side in back. Nothing. I emery clothed both the pads and the rotor. Nada.

I just switched the pads from the front wheel to the rear wheel figuring the rear pads would bring the "hmmmmmm" to the front. The back still hums.

I loosened the nut holding the angle of the hose entering the rear caliper and changed the angle just a little bit, then retightened that nut. Nada.

If the only thing anyone can say is "oh, you need organic pads back there" I will point to my silent front brake. Does Avid have some FAQ on this with real answers or at least other things I can try? I can always put my BB7 back on the rear. ;)
 

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noMAD man
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Have you read the bulk of posts here that discuss this? I've repeated this many times in some of those other posts, but somehow I think this Avid issue is caliper related. I tried all the things you mention with one Juicy and one Elixir caliper. I even transferred the whole Elixir unit to 3 different bikes with no success. Whatever is going on with that particular caliper was fixed by changing to a different semi-metallic brand pad with an alloy back. This also worked with the Juicy unit. Whatever was in the different pad compound and/or backing material broke the cycle of sound and vibration.

Just moving the OEM Avids pads around and even using new Avid OEM pads did nothing to kill the problem. The first conclusion to jump to would be that the OEM pads are the issue, but perhaps it's really the caliper "and" the pad combo, since other calipers with OEM pads seem to work just fine. I don't think you just have to use organic pads either. I like sem-metallic pads, and I just changed the brand and the backing material. Whether it was the slight change in the pad compound or the backing material or both, I'm not sure. The main problem, however, seemed to be isolated with the individual caliper. My other Elixir calipers and OEM Avid pads worked great without noise and vibration, as well as the several sets we've had through the shop. It must a very small overall number of Juicy/Elixir units that do this, but it's very annoying if you have one.
 

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Discussion Starter · #3 ·
TNC said:
Have you read the bulk of posts here that discuss this? I've repeated this many times in some of those other posts, but somehow I think this Avid issue is caliper related. I tried all the things you mention with one Juicy and one Elixir caliper. I even transferred the whole Elixir unit to 3 different bikes with no success. Whatever is going on with that particular caliper was fixed by changing to a different semi-metallic brand pad with an alloy back. This also worked with the Juicy unit. Whatever was in the different pad compound and/or backing material broke the cycle of sound and vibration.

Just moving the OEM Avids pads around and even using new Avid OEM pads did nothing to kill the problem. The first conclusion to jump to would be that the OEM pads are the issue, but perhaps it's really the caliper "and" the pad combo, since other calipers with OEM pads seem to work just fine. I don't think you just have to use organic pads either. I like sem-metallic pads, and I just changed the brand and the backing material. Whether it was the slight change in the pad compound or the backing material or both, I'm not sure. The main problem, however, seemed to be isolated with the individual caliper. My other Elixir calipers and OEM Avid pads worked great without noise and vibration, as well as the several sets we've had through the shop. It must a very small overall number of Juicy/Elixir units that do this, but it's very annoying if you have one.
Yeah, I'm the kind of thread starter who does an extensive search before I begin but, no, I didn't read your theory of Elixir caliper/pad-backing combo causing the offending oscillation. I'm glad you replied this quickly. I too like semi-metallic pads. I guess I'll order some other brand like you suggest with alloy backing. At least I know I now have a spare set of pads for the front!
 

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Discussion Starter · #4 ·
I said I like "semi-metallic" as well. What I meant was I like the sintered aka "metallic". Now I read where "semi-metallic" means "organic". I can find "organic" stock Avid pads with aluminum backing but I can't find anything called "semi-metallic" or "organic" for the Elixirs in another brand. TNC, you wanna tell me which brand pads you're specifically referring to?

In fact, the only non-Avid Elixir pads I can find is from Discobrake and they're not described as having alloy backing and it's their cheapest compound.
 

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which pads exactly?

So TNC, what exact brand pad did you use that had a semi-metallic pad with an alloy back? My apoligies if you already adressed this but I also have the crazy bad vibration problem on my new Elixir rear brake. I have had the turkey gobble with the Juicy's before, but this Elixir vibration is on a entirley diffrent level. I dont want to waste time/money trying diffrent brands that might not work.

Thanks :thumbsup:
 

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Discussion Starter · #6 ·
elsinore said:
So TNC, what exact brand pad did you use that had a semi-metallic pad with an alloy back? My apoligies if you already adressed this but I also have the crazy bad vibration problem on my new Elixir rear brake. I have had the turkey gobble with the Juicy's before, but this Elixir vibration is on a entirley diffrent level. I dont want to waste time/money trying diffrent brands that might not work.

Thanks :thumbsup:
Well, at least I've proven you can't do a dam thing about it except maybe change pads. I've become an expert on centering calipers, though.
 

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noMAD man
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I used Jagwire Red Zone semi-metallic pads with alloy backs. I don't think the Red Zone moniker is that important, as I didn't see any other semi-metallics in their lineup anyway. At the time, I only bought the Jagwires because QBP was temporarily out of Avid pads for a spare set to just keep on hand in an emergency. I had no real reason for thinking it, but I felt the Jagwire pads were probably going to be inferior but fine in a pinch compared to the Avids. Installing the Jagwire pads was just a knee-jerk effort after trying all the other methods of stopping the vibration which seemed more logical. I really didn't expect it to make a difference. After much riding, also with 2 hard weeks in Moab, I found the Jagwires to be extremely good...every bit as good as Avids, and of course without the vibration.

xcguy, I don't think there's a squat of difference in what these companies are calling metallic and semi-metallic. I don't think the term semi-metallic and organic are used interchangably...at least anymore. The additiion of a small amount of non-metallic material in the compound of semi-metallic pads is usually just to make them a bit quieter. I'll bet a nickel that most pads marketed as metallic have the same application of material. Jagwire has a separate organic pad for those who prefer them.

It would be great if someone could "without a doubt" identify the cause of this vibration. I moved that offending caliper to 3 bikes, and it continued vibrating. I thought someone was on to something when they suggested caliper mount facing, but I think that was pretty well addressed by my moving of the caliper...and then another identical calper on the same bikes was vibration free. So it would appear that the issue is in "that" one caliper. It just seems that whatever that issue is, it is aggravated by the OEM Avid pads. I think the issue still exists, but the pad/backing design apparently defuses vibration dynamics. Hey...I don't claim to be an engineer either, but the same fix applied to a Juicy 5 on another bike. My best assessment is that something is working in concert with a given caliper issue and the Avid OEM pad design for this to occur. We have tons of Juicys and now quite a few Elixirs go through the shop, and this issue has only surfaced on two occasions. You see it mentioned a lot here, but that must be spread out over who knows how many sets out there.
 

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xcguy said:
Well, at least I've proven you can't do a dam thing about it except maybe change pads. I've become an expert on centering calipers, though.
It's not just the Elixirs that Howl, right. Obviously the Juicy's do it but my buddies brand new Shimano XT's do it as well. Just the back one's. Has anybody tried tightly wrapping a inner tube around one of the chainstays or the seatstays. It seems like the pad material,backing,etc. are all causing harmonic resonance in the rear triangle and rotor. If you increase the mass of an object, you change it's resonance frequency. Think of it like putting your finger against a tuning fork. It stops the sound.
My Hayes 9's rarely make noise and I use their OEM metallic pads and my Code 5's rarely make noise and I use OEM metallic pads as well. I do have 8" rotors on both bikes so that may be why.
XC guy, I assume you are running 6" rotors, well because you are a XC guy.
I think the front brakes don''t vibrate as much due to the mass damping and weight that is on the fork. My wife is running a 8" original G1 rotor on her hayes 9 front and it rarely squeals. This is the hated Avid rotor of a few years ago. It works great.
The only way I can think to solve this issue is to break up the harmonic synergies.
 

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noMAD man
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Worm, I was wondering if you had ridden a set of Juicy/Elixir models with this weird deal. It's not just a sound. It's a truly funky "shudder" that resonates all through the bike. On some bikes it will flat out make your privates tingle on the saddle...good or bad depending on your state of eroticism...LOL!

I think you're on to something as it relates to distinguishing why it's more prevalent on the rear than on the front. The fork is probably not as good a transmission medium of this vibration, but some do exerience there too. Another curiosity to me was how this one caliper continued this vibration with the stock pads on an SJ FSR, a Nomad, and an '03 Bullit. The Bullit probably has the least complex rear end with very substantial frame members and swingarm, but the vibration came through anyway.

I definitely agree with your idea on the harmonics, and apparently it doesn't take much to "break it up". My caliper did this with both 160 and 185 rotors. Since it was on the rear, I didn't try it on a 203.
 

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TNC said:
Worm, I was wondering if you had ridden a set of Juicy/Elixir models with this weird deal. It's not just a sound. It's a truly funky "shudder" that resonates all through the bike. On some bikes it will flat out make your privates tingle on the saddle...good or bad depending on your state of eroticism...LOL!

I think you're on to something as it relates to distinguishing why it's more prevalent on the rear than on the front. The fork is probably not as good a transmission medium of this vibration, but some do exerience there too. Another curiosity to me was how this one caliper continued this vibration with the stock pads on an SJ FSR, a Nomad, and an '03 Bullit. The Bullit probably has the least complex rear end with very substantial frame members and swingarm, but the vibration came through anyway.

I definitely agree with your idea on the harmonics, and apparently it doesn't take much to "break it up". My caliper did this with both 160 and 185 rotors. Since it was on the rear, I didn't try it on a 203.
I fortunately haven't had to ride a bike with the issue for any length of time but I do know what you are describing. It's as if the pad is skipping or stuttering across the rotor and a vibration propagates to your junk.
Like when you throw a ice cube onto a hot griddle. I would think that the plastic caliper pistons(hayes uses them) and rubber seals would break up any resonance to the swing-arm via the caliper. But if you think about it, the rotor,hub, will or could transmit via the hub-axle frame connection.

My wife has 160mm Hayes 9 with sintered pads and no major issues. I run 203's for no reason other than I had the set.
As to the same caliper causing the issue on different bikes, That's a tough one. I am assuming you used different wheelsets on the different bikes. Maybe the caliper piston seals are too weak or misaligned or something that cause the piston to oscillate, vibrate or whatever.
 

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Discussion Starter · #11 ·
TNC said:
Worm, I was wondering if you had ridden a set of Juicy/Elixir models with this weird deal. It's not just a sound. It's a truly funky "shudder" that resonates all through the bike. On some bikes it will flat out make your privates tingle on the saddle...good or bad depending on your state of eroticism...LOL!

I think you're on to something as it relates to distinguishing why it's more prevalent on the rear than on the front. The fork is probably not as good a transmission medium of this vibration, but some do exerience there too. Another curiosity to me was how this one caliper continued this vibration with the stock pads on an SJ FSR, a Nomad, and an '03 Bullit. The Bullit probably has the least complex rear end with very substantial frame members and swingarm, but the vibration came through anyway.

I definitely agree with your idea on the harmonics, and apparently it doesn't take much to "break it up". My caliper did this with both 160 and 185 rotors. Since it was on the rear, I didn't try it on a 203.
You got that right that's it "truly funky shudder" you can feel it through your bones. It's not like the squeal I get from my BB7s after I wash my bike. It's like putting a tuning fork at maybe F above middle C up to your teeth!
 

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I'm about to change my newish Elixir CRs to my new (replacement) Nomad frame today, from the Heckler they were residing on in the meantime, and hopefully I still will not have this issue I've read about and haven't jinxed myself by mentioning that. Never had it on the BB7s with any Avid rotor or any of my bikes (although they're all SC bikes), didn't have it with the CRs (stock Avid semi-metallic pads/G3 rotors 185f/160r).

One thought I had, if it is indeed just that some caliper/pad combos create this harmonic, isn't there some sort of product for automotive disc brakes can use to reduce noise, a backing that's applied to the pads? Wonder if something like that would help.

To anyone's knowledge has a good dialogue ever been opened with Avid on the subject? Or do they just not deal with it? Seems like they would be all over this, but maybe they're stumped too?

I've mostly been of the mind that's it's gotta be more with the particular alignment of the caliper to rotor, but that sure doesn't sound like the case the more I read...
 

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Leading edge beveled

I had that same howl on my new elixir r rear brake too. I took the pads out and made a 45 degree bevel on the leading edge and most of the howl is gone. Sometimes if while moving at lower speeds and I lightly apply the brake, I get a small howl that I can control by modulating the pressure on the lever.

Many years ago I had a Yamaha DT 250 with drum brakes that would howl something like the elixirs. The cure at the time was to make a bevel on the leading edge of the shoes and a small beveled lateral slot in the mid point of the shoe. Problem solved.

I might pull the pads and add that small beveled slot today and try it tonight and see if the problem is completely eradicated.
 

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noMAD man
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Bikinfoolferlife said:
I'm about to change my newish Elixir CRs to my new (replacement) Nomad frame today, from the Heckler they were residing on in the meantime, and hopefully I still will not have this issue I've read about and haven't jinxed myself by mentioning that. Never had it on the BB7s with any Avid rotor or any of my bikes (although they're all SC bikes), didn't have it with the CRs (stock Avid semi-metallic pads/G3 rotors 185f/160r).

One thought I had, if it is indeed just that some caliper/pad combos create this harmonic, isn't there some sort of product for automotive disc brakes can use to reduce noise, a backing that's applied to the pads? Wonder if something like that would help.

To anyone's knowledge has a good dialogue ever been opened with Avid on the subject? Or do they just not deal with it? Seems like they would be all over this, but maybe they're stumped too?

I've mostly been of the mind that's it's gotta be more with the particular alignment of the caliper to rotor, but that sure doesn't sound like the case the more I read...
Bikin', if I'm right you won't have an issue changing the brakes over to another bike. It seems inherent in a given caliper...or brakeset.

On that "disc brake quiet" substance, I've used some of that stuff on motorcycle discs in the past. From my experience it didn't last long, but it might be more substantial on a bicycle. I thought the stuff was a bit messy. I would describe it as a kind of silicone, glue-like consistency.

Ask Avid?...that might take all the challenge out of it.:D Seriously though, working at a shop, I'm somewhat amazed and usually disappointed at the somewhat obvious lack of knowledge you get from some tech people in the bicycle biz. Don't get me wrong. There are some who know their stuff and have it together. As to your comment about them perhaps being stumped, I'm disappointed that recently when I went to pull up the latest bleed info for some Elixirs, I found 3 relatively different methods in text and vid info...and then I deviated even from those. On the other hand, I was very impressed with their tech vid on rebuilding the Monarch rear shock.
 

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Discussion Starter · #15 ·
What's got me shaking my head is the fact that, once I figure this out and maybe the Jagwire Red Zone (or other) pads are the answer, after all this messing around with brand new Elixirs I'll be right back where I should have started, with brakes that "work" right out the box.

It's not like all this effort I'm putting out here is "improving" my bike, it's like fixing a huge flat. There, now I can ride again.

I'm a rider who's only had BB7 disk brakes, on six bikes, for four years, and they were all flawless. So this adventure into the world of hydros...well, I guess it's always something with hydros. Just like I'd heard and thought I'd avoid through stored good Karma or something. :rolleyes:
 

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noMAD man
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xcguy, when you get your noise/vibration deal sorted out, I think you'll find the Elixirs to be about the best performing 2-piston hydros around.
 

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TNC said:
xcguy, when you get your noise/vibration deal sorted out, I think you'll find the Elixirs to be about the best performing 2-piston hydros around.
Until he tries Shimano XTR...
 

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Discussion Starter · #18 ·
TNC said:
xcguy, when you get your noise/vibration deal sorted out, I think you'll find the Elixirs to be about the best performing 2-piston hydros around.
Well, let's just say that I've never had a bike problem I couldn't sort out in a shorter time span than this rear Elixir howl. I'm still optimistic that I'll be able to solve it. However, I've read many threads where riders just gave up and went with some other brand than Avid Juicy's or whatever...if it gets to the point that I've tried everything and it still isn't resolved Avid is gonna hear about it. Again and again till they send a rep to experience what I've got and solve it themselves. As a loyal BB7 user I cannot believe that Avid would produce a hydraulic disk brake so finicky that a pretty mechanical guy such as myself can't figure it out. Even if it means they issue a recall saying "in a few cases there's been reports of a "hmmmmm" coming from the rear brake on the Elixirs that just cannot be resolved. Hey, sheeit happens...send in your offending rear brake and we'll replace it, free of any charges". Since I'm sure Avid's position is that it's a completely rare occurrence they shouldn't be out much $$, right? But they'd sure gain buyers' respect for handling such a funky issue correctly.

Really, I'm still optimistic. What keeps me optimistic is that I have my Superlight with BB7s on it that I'm gonna ride in the meantime.
 

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I am poor. In my defense everyone knows how good XTR parts are. I don't have any firsthand XTR experience I was just going off what some others had told me...

Sorry
 
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