Avid J7 - A squeal test
- hayes mud cutter rotor
- run for 3100 miles since 1.1.2004 with an XTR caliper
- no major wear on the rotor
- used both metallic and resin pads
- zero problems or squealing unless they got wet then only until dry
- disk mount faced
- rotor cleaned
Put an avid J7 on the front using the existing rotor to see how it would perform. Interestingly, it squeals intermittently and seems to be more related to ambient temp and how long the pads are in contact with the rotors. If it is warm then it only takes about 2 secs of braking for the squeal to dissipate but if it is cool ( 45 F or less ) it squeals almost continually. The pads are the new B4 pads. I then put the XTR rig back on and ran both resin and metallic pads and get zero squeal. This leads me to believe that the majority of the squealing problem is related to the pad compound and that all the fixes that I have seen ( dremel rotor ect ) are just compensating for the pad. This is also consistent with peoples comments about galfer and EBC gold pads not having the same issues.
all single...all the time
I suspected pad compound also, but I tried Galfer, Fibrax FMC, EBC Gold, a bunch of Avid's own, and the differences were really not as great as I would have guessed.
you had the same squealing problems with all the different pads?
I find it interesting that I have seen very few complaints about XTR calipers squealing with the regularity that I see for other manufacturers. Actually I see very few complaints, after the first rev, about the XTR calipers at all. I found an interesting GM Article about their process to address brake squeal and I am coming to the conclusion that Avid may have a caliper/pad combo that is just more sensitive to the problems mentioned in the article ( plus rider weight ). Why this is I do not know but it blows. My hope is that the brakes do not exhibit the same issues on the girl's new ss or I am sure they will go to EBay in a hurry.
all single...all the time
Mine never let out a peep when they were dry aside from an occassional squeak (when not braking) when they got really dusty in the desert. Warm, cold air, hot, cold rotor, pretty much silent with all pads. My first year on them I was even able to keep them pretty quiet in the wet, but I did have to mess with them in this department and try different stuff. Then this fall, a year into having them, they just went off in the area of noise. Very strange. No pad/rotor combo or deglazing operation would shut them up in the wet. I got some Louise FRs on a demo bike I bought and was immediately impressed at how they almost never uttered a peep no matter what the conditions were. I got a few more off eBay used, or new but cheap, and now have Louises/FRs all around. I still like the Juicys better in many ways, but I cannot deal with the noise when it's almost always wet where I live.
I dremeled the rear J7 last night, and I tried in my court. After a few tries, the rear started pulsing and making this weird noise. I'm wondering if it's a pad thickness problem.
Originally Posted by tscheezy
Faster is not always better, but it's always more fun
Riding free's the mind
Ever since I replaced my pads , cleaned the rotors, realigned the calipers and bleed them- seemed to have aleaviated the "dry" noise/pulsing issues.
I'm wondering if the pulsing is due to misalignment. As you all know, the CPS system allows the caliper to float in all directions, which might result in the calipers mounting slightly skewed. Maybe this causes the pistons/pads to contact the rotor at an angle and throwing off the tolerances thereby causing viibration....my speculation.
The J7' s are still loud when their wet. Wondering if there's a way to dampen the rotors- essentially deadening the harmonics that are created when the pads vibrate on the surface of the rotor.
Question to a custom frame builder..."So what makes your bikes climb better?"....his answer, "Uh, your legs?"
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