Rear wheel shutter under braking [avid elixirs]

Cano29

Cano29

Likes Dirt
Hello again,
I got a 2010 giant faith with avid elixir CR brakes running stock standard everything, spring wheels hub etc. Under heavy braking the rear end shutters a lot. The further I move back and the more weight put on it the worse it gets. I'm not 100% sure of what it might be. Wheels seem to be straight frames not bent rotors look straight. I can't seem to figure out what it is. Any advice or has anyone had this problem before?
Thanks
 
harmonix1234

harmonix1234

Eats Squid
What size rotor on the back?

I had the same problem and went down a size in rotor and it stopped. The larger surface/diameter was turning the rotor into resonator (like running your finer around the rim of a crystal wine glass). It was so bad it would vibrate right through the bike and up the jacksie. Like farting fizzy butterflies.

Is it fine vibration/humming sound, or shuddering?
 
A

anth69

Likes Dirt
did you wash your driveline with degreaser ? swap the pads front front to rear and see if the problem follows pads
 
Cano29

Cano29

Likes Dirt
It's more shuddering than vibration but it vibrates throughout the bike. The rotor on the rear is actually a 8" stock is 7". That might be the problem. I don't think it's the pads because there relatively new. The only other thing I can think of is the maestro link down the bottom might be loose?
thanks
 
K

Kramer

FoBR
I get this sometimes with my Avid Juicys - a find a few really hard high speed stops will stop the vibrations.
 
S

Shredden

Knows his goats
Have had the same problem with my elixir 5's. Put up with it for a bit, then demolished my rear rotor (203mm G2) on a rock. Took the oppurtunity to switch to a 185mm rear G3 as I am only 65kgs. Problem was gone...
 
Cano29

Cano29

Likes Dirt
Been reading a bit and sometimes they say that changing the mounts may fix it. Might have to try some smaller rotors as well.
 
Nerf Herder

Nerf Herder

Wheel size expert
are your bolts tightened to recommended torque on the mounts ... do you have the correct adapters (ie, 185 rotors with 180mm adapters or whatever combination)

as you've pointed out ... check your pivot bolts.

good luck
 
H

hennez

Likes Bikes
I've had 2 sets of juicy's and they both did that.. tried changing rotor/pads etc but couldnt get it too stop properly. Shimano brakes are far better.:rockon:
 
shakes

shakes

Likes Dirt
Brake pads are NOT parallel with the disc. Almost garuntee you that is it.

Pull the pad's and see if they are worn unevely.. Or with the wheel in the bike, shine a torch up(or lay some white paper behind the caliper) from underneath and see if the disc runs true and pad's sit evenly.
 
C

casnell

Likes Bikes and Dirt
shakes said:
Brake pads are NOT parallel with the disc. Almost garuntee you that is it.

Pull the pad's and see if they are worn unevely.. Or with the wheel in the bike, shine a torch up(or lay some white paper behind the caliper) from underneath and see if the disc runs true and pad's sit evenly.
Click to expand...
That'll be it. New pads will fix it, or even swapping pads around. Seems to happen if they've been run in mud even if there's still a bit of life in the pads.

PS happens to XT brakes too, it's not an Elixir exclusive...
 
N

niki125

Likes Dirt
I probably don't have to say this but don't wash your brakes down with degreaser like someone suggested earlier. Brake clean or alcho only.
 
Cano29

Cano29

Likes Dirt
yeah thanks anyway. We got some brake cleaner in the shed somewhere. Wouldn't have used degreaser, oil based isn't it?
 
noddy

noddy

Likes Dirt
I have a Haro shift which did the same, nothing affected the vibration, tried different brakes etc. turns out the shock was stuffed. new upgraded shock and it instantly disappeared.
the vibration i noticed was more of a shudder, could be felt when drifting the bike without brakes too.
since you just bought the bike 2nd hand maybe check the boost valve pressures/oil condition???
 
Last edited:
Sputnick

Sputnick

Likes Bikes and Dirt
As said the brake is not parallel to your disc, but new pads will not fix this.
New pads will just start off good, and then wear down the the same point and continue the shuddering.

You need to have your brake tabs faced at your LBS, which will make the tabs completely parallel with your frame.
 
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