[mcrumble69]

i went for a ride yesterday and every time i put torque on the pedals the rear rotor would rub the pads and squeel.any ideas why this is happening and how i can fix it?
ive had this bike/frame for 6 months and the wheels and brakes for almost 2 years and this has never happened.
the rear wheel qr and hub are tight and so is the rotor.
the brakes are hayes hfx 9 with 6in rotors .the wheel is a azonic outlaw. and the frame is a 06 mountain cycle fury.
thanks

 

[XSL_WiLL]

Check for play in the hubs and pivots.

 

[mcrumble69]

there is no play in the hub. by pivots do u mean frame?if so the pivot(single pivot frame) is also tight.everything on the rear of the frame/swingarm seems to be tight thats why im so confused:madman:
thanks

 

[XSL_WiLL]

Check the pads for glaze or contamination. The caliper may need to be recentered. While doing so, make sure both the pistons are pushing out and retracting freely.

 

[beagledadi]

Hijacked...

Sorry to butt in, but I think I have a touch of that problem.

When I spin the front tire it turns a couple times and then stops abruptly. The hubs are good and there's no play I can feel/see. I've replaced the pads, but what XSL_WiLL said about the pistons retracting is what caught my attention.

How do you know if they are retracting? Could it be temperature related, for hydo brakes? Is there a stronger little clip that holds the pads away from the rotor just a hair more??...mmmm, upgrade$$$$. I'm kinda new to disc brakes, people said they would drag a little, but I thought it would pass after a few rides.

 

[mcrumble69]

Check the pads for glaze or contamination. The caliper may need to be recentered. While doing so, make sure both the pistons are pushing out and retracting freely.

i just finished doing what you said. it is quieter but still rubs.(just the rear) its rubbing ONLY when i put torque on the pedals out of the saddle and pedaling hard. its fine when im pedaling at a normal pace.and like i said its never done this before. so i dont know what to do next:madman:
thanks for your help.

 

[crisillo]

i just finished doing what you said. it is quieter but still rubs.(just the rear) its rubbing ONLY when i put torque on the pedals out of the saddle and pedaling hard. its fine when im pedaling at a normal pace.and like i said its never done this before. so i dont know what to do next:madman:
thanks for your help.

It definitely sounds like your wheel is shifting its position..... are you sure the rotor is completely true?? I have had a rotor that is slightly out of true rub more after it warms up..

 

[XSL_WiLL]

What brakes?

It's more likely that your caliper needs to be centered, or your rotor is not totally true. Or a combination of the two.

Yes, temperature can affect the piston position. If the fluid expands and the resivoir can't hold that fluid capacity, then it will push the pistons out.

 

[Douglas Fir]

Yo Beagaldadi- rotors should not rub

Yo beagle, anyone telling you that your rotors rubbing is natural is a hack mechanic that does no how to tune the things. Check out the retraction as xs will suggested- usually it is water contamination in the hydros.
BTw morningstar makes several rotor tuning tools check them out at utahmountainbiking.com

 

[XSL_WiLL]

Sometimes, due to frame/fork flex, a little bit of rubbing/deflection can't be avoided.

 

[juancancook]

I agree..

..partially w/ XSL Will. Skinny legged XC frames and discs can be chatty due to flex in the frame, but there's another fly that could be in the ointment.
Calipers do need to get overhauled from time to time, more so if bleeding yearly isn't on the maintenance regiment. These things behave like a suspension fork, cycling in and out with engagement and release of the lever. Anyone who doesn't change their fork oil over the course of time knows how smmmmmoooooth the thing runs when they finally get around to it. Same with the caliper. It's cycling in dirt, pad and rotor material, water/mud, the odd gopher, and/or dog piles. If ya haven't had the problem for the 2yrs you've owned the brake then I suspect it's all a matter of taking the thing apart, cleaning it out w/ isopropyl alcohol, swapping out the transfer port o ring (for good measure) and maybe replacing the pistons and square seals (also for good measure as they are considered a wear item). Not a hard job, but one that should be left to someone who can bleed a brake proper like. I believe, but may be wrong, that all disc brake manufacturers recommend the same from time to time. Anybody from the manufacturers care to comment? It'll help mech's like those of us who kill time during the winter months reading/posting on these forums help folks out during the summertime who ride your stuff.

 

[Psycho Mike]

The three main items discussed are the top of my suspects list...set-up issue (caliper not centered, disk not true or similar), maintenance issue (caliper not retracting, need of a bleed) or frame flex would be the order of things I'd look at.

Be patient and a bit of a perfectionist when you're working on the brakes....once they are dialed in, they can be a true thing of beauty and whisper silent.

 

[mcrumble69]

thanks for the great info everyone i fixed it. i tore down the whole back half of my bike and cleaned,adjusted,regreased and or locktited everything from the main pivot back. now its not making a sound.the only actual part i changed is the rear QR.
now when i have another day off ill do the front half and start on my other bikes
thanks again
eric

 

[juancancook]

Attabiker! Curious, what brand was the original Q/R?

 

[mcrumble69]

Attabiker! Curious, what brand was the original Q/R?

the QR was a azonic that came with the wheelset thats on the bike. the one im using now is a unknown year shimano xt i took from a small QR stash i have accumulated over the last 15 years lol. its too bad the purple ano ones weren't long enough

 

[beagledadi]

What about.....

If I flip the bike upside down and let the wheel sit in the shocks dropout without closing the skewer, the wheel turns freely. As I close the scewer slowly, I can see the rotor start to "lean" slightly in twords the caliper/pad....what do you think is causing that?? Maybe the shock dropouts are wearing out and are no longer even on both sides?? Now what ??

 

[mcrumble69]

thanks for the great info everyone i fixed it. i tore down the whole back half of my bike and cleaned,adjusted,regreased and or locktited everything from the main pivot back. now its not making a sound.the only actual part i changed is the rear QR.
now when i have another day off ill do the front half and start on my other bikes
thanks again
eric

ITS BACK:madman: after tearing the bike down and going through everything its rubbing again! now im totally confused:???: its a single pivot could it be the swing arm flexing?
also ive been riding in cold weather (it was 30 degrees yesterday and colder with wind chill)could that have anything to do with it?
heres a pic so u can see the swingarm design.

Thanks again
Eric

 

[XSL_WiLL]

When you tighten the QR, you aren't always tightening it to the same position/torque. This will cause the wheel to sit in the dropout a little bit differently, or deflect a bit differently.

The solution? Don't take off your wheels. Or get a QR with a stop built in.

When you checked everything, did you check that both pistons in the caliper were moving in and out freely?