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7am Backcountry ;- )
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Discussion Starter · #1 ·
Hey guys,

My HFX 9 have been great no rubbing, good range of motion on the lever and good stopping power.

I decided to buy some sintered brake pads and get the LBS to fit them (my Hayes are only 3 months old but thought this would be a relatively cheap and straightforward upgrade)

Collected the bike last week and the mechanic told me upon changing the brake pads the pistons are seized :madman:

Now the front wheel spins and rubs slightly, the back wheel rubs very badly (ie i'm going to struggle to pedal uphill there is so much rub) and the brake levers engage the pads fully when I press them in about a quarter of an inch.

Lever with no pressure



Lever fully depressed



Note the difference in position, there hardly isnt any.

Also whether caused by these 'seized pistons' or the mechanic trying to put this right the cap below was off on the rear caliper and some liquid has seeped out



I asked could I push the pistons back in but he said it can't be fixed. I'm really p*ssed off :???:
 

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Um a week to change brake pads?

Try recalibrating your calipers. First remove the brake pads. All you have to to is flip your bike upside down take your wheel off and yank on those tabs on your disk brakes. They should come off easily try needle noise pliers of your fingers are fat. Then gently press the pistons back in with a screw driver or a 8mm allen wrench. Replace the brake pads. The pads have a small clip that attache to the piston center pin. Loosen the 2 bolts attaching the caliper to the brake adaptor and replace your wheel. Making sure your wheel is on straight and normaly tight. Then have a helper gently press the brake lever down and pump it a few times. Then have your helper hold the brake lever down like braking and tighten the two bolts. This should recenter the pads. It will take a bit of time for the pads to wear in. You might have to do this a few more times while you get ot to wear in and then you will have rub free brakes.
 

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7am Backcountry ;- )
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Discussion Starter · #3 ·
SLX supurb advice thanks!

I'm having trouble pushing the pistons back in, I have tried a 10mm spanner with the open end so as not to damage the post in the middle and an 8mm allen key.

Its like a circular plate i'm trying to push in there is a tiny amount of movement up and down but it won't push further back :(
 

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Meh.
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17,508 Posts
You can put the pads in, and use a screwdriver in between the pads to push it back. That eliminates the risk of snapping those posts. You may gouge the friction material a bit, but no big deal.

If you still have trouble pushing the pistons in (ie, one goes in, the other comes out), the system could be overfilled. Visually inspect the line and fittings, and seams for any leaks or seeping. If there are any leaks, the DOT fluid could be drawing moisture in from the air, which would cause it to become overfilled. If you do not see any leaks, remove the plug from the bleed port at the lever (put it somewhere safe so you don't lose it). And with that bleed port open, try again to reset the pistons at the caliper.

It sounds like the mech just depressed the lever without a rotor between the pads. And it's ridiculous that nobody caught that.
 

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So your bike was fine before you brought it in and after a brake pad change, both brakes are "seized"? I'd talk to the shop owner and then learn how to do it yourself. It only takes a couple of minutes to do that job...not a week
 

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7am Backcountry ;- )
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Discussion Starter · #6 ·
The mech must have done both by mistake, I wish I would have done it myself now I was having some new chainrings fitted for free as I bought them there and he said he would chuck on the brake pads while he was doing it.

But yeah the brakes were fine before I took them in and now the back wheel barely turns and the front drags.

I've put the pads on and using a screwdriver am trying to force the pistons back the problem is both brake pads actually protrude the edge of the circular pistons so am I right in saying the furthest back the can go is plush with the edge of the circle?
 

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Still learning
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Hm, I seem to have a very similar issue with the HFX9s which are on my Giant Talon. The bike is less than four weeks old, but I'm noticing a strangely small amount of travel in the brake lever which I expected to be a lot more (I've gone straight from old cantilevers to the HFX9s, so I don't really know the difference as to what's expected).

On mine both the front and rear graze the pads quite frequently (ie, around corners etc), though they're not rubbing during normal motion.
It's supposed to go back after six weeks, though they said because of the amount of riding I'm doing (~40km/night) to bring it back around now, so I'll get them to check up on that - does this sound like the same kind of problem? (I seriously know SFA about discs)
 

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Meh.
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If it's just the occasional "ting" when cornering, that's not a big deal. The frame/fork will flex a bit. After the brakes bed-in it should get a little bit better. You can have the reach adjusted to address the lever issue. It adjusts via a 2mm allen by the knuckle.
 

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7am Backcountry ;- )
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Discussion Starter · #10 ·
akashra said:
Hm, I seem to have a very similar issue with the HFX9s which are on my Giant Talon. The bike is less than four weeks old, but I'm noticing a strangely small amount of travel in the brake lever which I expected to be a lot more (I've gone straight from old cantilevers to the HFX9s, so I don't really know the difference as to what's expected).

On mine both the front and rear graze the pads quite frequently (ie, around corners etc), though they're not rubbing during normal motion.
It's supposed to go back after six weeks, though they said because of the amount of riding I'm doing (~40km/night) to bring it back around now, so I'll get them to check up on that - does this sound like the same kind of problem? (I seriously know SFA about discs)
What brand of pads are in there?

I think I might have found the problem. The LBS put goodridge pads in which are very thick - too thick in my opinion, the pistons are all the way back so I don't know where the bike shop got the seized pistons comment from?

The pads sit flush against the circular body on either side. Now these new pads look a bit too thick. When I press the lever instead of having some travel before they hit the disc they hit the disc instantly - there is hardly any gap at tall between the disc and pads.

The lever engaging straight away I find dangerous as there is no modulation or control. I reckon sanding down my goodridge pads would return the brakes to their previous performace.

(Anyone please got a measurement of the Original Hayes pads thickness when new?) so I can test my theory?

Anyhow ive bought some Avid Juicy 7's 2007's now and very impressed. They were a breeze to setup pumped the lever 6 times and they autocentered the caliper have a sexy adjustable cable routing screw which I thought was a nice touch as my hayes cable used to stick out the back of my bike and bend quite sharply - but I still want to fix my hayes so I can ebay them :)
 

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The piston on my rear Hayes 9 seized a while back. It seemed I always had a little bit of brake rub. When it came time to change the rear pad I noticed the seized piston. I tried removing all the oil, wd40, and gingerly pulling on the piston, but in the end it just would not move. So I broke it off, and saw that some piston material had bonded to the metal inside the caliper. It only came off when scraped with the tip of a screwdriver.

My point is, maybe your pistons were already seized, and the new thick pads are just making that apparent. Hopefully yours are not seized to the point where they are beyond repair. I was lucky that I was able to find some OEM Juicy 5’s real cheap on ebay. Good luck.

Ant
 

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XSL_WiLL said:
If you want to repair those 9s, you can get new pistons. Next time, use compressed air to blow the piston out of the caliper half.
Thanks, but that piston was NOT going to come off with compressed air. It had to be scraped off. I do have a new piston, but have been too lazy to install it and add the oil.
 
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