Disc breaks always rubbing

Sando

Hi all

I have a Giant XTC 2 with Hayes 9 disc breaks front and rear. I find that both the front and rear breaks keep rubbing on the pads.

I have had the bike serviced but it hasn't made much of difference... I have also spent time trying to 'line them up properly' but they go back to rubbing shortly after riding...

I ride the bike on the road mostly and I feel that this slowing me considerably - does anyone have any hints to prevent this from happening?

Ny Cykel

I thought they all drag a little, I had a used bike with Hyd. Units, don't use em anymore,wished I could help. I will ask around.

Gerald08

Yeah better not use them anymore, or use other breaks, hope i can help also,



Gerald

dabac

Disc brake systems have very little clearance, so setup must be just right to avoid rubbing completely.

is there an online manual or something that can tell you if you've done all the right things?

But there is a difference between rubbing a little and actually slowing you down. What happens if you lift the wheel off the ground and give it a spin? If it rubs bad enough to actually rob you of speed you should be able to feel the resistance in your hand as you spin the wheel.
If the wheel still will give you several revolutions with only a little brake noise when you spin it suspended, then it's not the brakes that are slowing you down

Drag should not be enough to slow you down - so if it is, first take it back to whoever serviced them and explain your problem, see if they can fix it.

If they can't help you - sell your disc brakes and set the bike up for V-brakes instead. Heck, you might even find someone willing to swap the parts with...

Rockslayer

I did have had similar issues my my discs brakes but there was no going to V's especially on downhill tracks. I actually find them pretty low maintenance as long as you look after them. It's unusual both would be playing up at the same time.
On regular pavement you should not have any problems.

Firstly if you are constantly removing and remounting the wheels you need to make sure that they are in correct position all the way down in the bracket and spin the wheels to make sure they spin freely before tightening. A little bit misaligned they will rub.
They do clog with dust from the brakes or dirt etc.. you need to wipe down the discs, someone suggested brake disc cleaner for motobikes or just use a clean cloth and wipe them down. The often make a light rubbing sound due to minimal clearance and dust in the gap if it doesnt slow your wheels down you just ignore it or what I do is hold the brake levers down a bit and ride a little to let the brakes rub itself clear.

Rain/Water (this is where my problems started) disc brakes don't like getting wet, never hose or wash them it either puts fine dust or grit into the calipers/pistons and they can jam and not release.

Check to see when you pull the brake levers if the brake pads close onto the discs and release there should be some clearance or an obvious gap up to half a mm. If it doesnt show obvious release the pistons are probably jammed. I havent worked on the Hayes before but you should be able to download some servicing/instructions from their website.

Are the discs bent? If so they need to be replaced or flattened back out.

If there is obvious clearance between discs and pads the calipers may be misaligned.You will need to realign the caliper unit. I am not sure with the hayes if they will automatically align when mounting. what you can do is loosen the screws that hold the caliper to the frame mounts on your bike, enough to give the caliper free movement. then either with tape or rope hold the corresponding brake levers down to clamp the discs tightly. Then tighten the screws again while the discs are being clamped. Once completed undo the levers.

If all that doesnt work,

You can try remove the brake pads and clean around and under where they are clipped and around the piston (**DO NOT PULL THE LEVERS during this process and you can pop the pistons out and make it leak and put AIR in the hydraulic hose**) Put the pads back in and try putting the wheel back in. If you are lucky this might work. If not you may have to open them up and clean the inside. could be a messy job with fluid, seal, bleeding etc which you need a kit to do.
Send it too a bike shop..

Hope that helps,

PSUcycling

besides the slightly warped rotor that was already mentioned, is that i believe that the hayes brakes do not use return springs between the pads. They only rely on square-cut piston seals to help retract the pad (exactly how a car rotor/pad works) the slight warp inherent in all rotors should brush the pad, and with the seals, push the pads just out of the way.

you will probably have to live with the problem if you have really set up the calipers correctly, You may want to switch to almost any other brand as they almost all now use some sort of return spring..

psu

__________________
Chann McRae Cycling Coach
Velossimo Racing Team
Racing Blog
john@cmcoaching.com

dabac

Do they? That must be a bugger to assemble...

PSUcycling

most of my experience is with shimano's and its really pretty easy, its not a spring in the traditional sense, but it slides in after you install the pads.

you can see a couple of them on this link: http://www.koolstop.com/brakes/DiscBrakes/index.php

__________________
Chann McRae Cycling Coach
Velossimo Racing Team
Racing Blog
john@cmcoaching.com

dabac

Ah, I was envisioning something that actually pulled the piston back from inside...

But I still don't understand exactly where that spring goes and how it can push the pads apart.

LJS

Rockslayer covers the field of adjustment pretty completely. One thing is to check the clearance on both sides of the rotor to each pad before riding and adjust if needed. With quick release axles, there seems to be some tendency for the axle to settle and move around in the dropouts as the bike is ridden, especially if the wheel has just been removed and put back on. This will change the clearance since the pads are mounted to the fork or frame and the rotor is mounted to the wheel. Put enough tension on the skewers to make them hard to lock in order to hold the wheel in position as tightly as possible. Ride the bike to let the wheel settle in and then check and adjust the brake.

garage sale GT

When my system starts to rub I just remove the wheel and carefully clamp it back in, ensuring it is fully seated and has the correct skewer tension.

I don't even bother to check if it's rubbing when the skewers are undone.

This is besides normal cleaning and stuff. It never fails.