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Disc brake help


By lonhro - Posted on 02 March 2007

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

I've taken my front wheel off and now can't get it back on because the disc brake pads have joined together. I've tried to wedge them apart and don't want to force the rotor in case it damages something.

I'm only new to disc brakes - Any ideas on how to get the wheel back on?

Tags

I take it these are hydraulic, not cable?

Try to tease the callipers appart with something soft that's not going to damage the pads (I assume the pads are still there, and they are touching?).

Plastic tire leavers might work. Or try a BFO flat head screwdriver, but this will probably damage the pads. Be real careful and you might get away with it. Still damaged pads with a wheel on is better than good pads and no wheel! Eye-wink

You should never pull the brake leaver when there's no wheel on the bike (or something disc sized between the callipers)... is that how this happened?

Pulled the brake lever accidentally when putting on the new fork! the calipers clamped together, took me good 30 minutes to get them apart by using a flat head driver and releasing a few drops of oil from the upper oil resevoir (use a Torx screw driver to do this SLOWLY)

Works fine again now but not sure what will happen when i really need the front brake!

If you have Avid brakes, they should come with the red plastic spacers

ahh ditto...

I wedged it apart a little bit with a plastic ruler, squeezed the brakes, then just went thicker and thicker each time (went from ruler to cardboard to layers of coasters) until the pads were far enough apart for the wheel to go back in.

I have Avid Juicy 5s on my Giant Reign...but never seen these spacers you speak of....would be handy the next time I take the wheel off...

Yeah I got one of the spacers with my Juicys (didn't have it in though!). You could also use two old credit cards.

I have Juicy 5's as well. If they come on the bike you don't get the spacers, if you buy them after market you do.

They will also do this to you on the trail though. It has happened to me three or four times now in about 8 or 9 months. They just seem to get tighter and tighter and then eventually lock on, obviously this happens with the wheel and therefore the disc on. This can happen in the space of a few minutes. Pull your wheel off and use the tyre levers as Rob said to pry them apart.

Ian, who also runs Juicy 5's has had the same thing happen. Told me he has had them bled and also bled them himself and neither made much difference but then showed me a nifty little trick.

Apply a little pressure to the brake lever. Using a Torx screwdriver very very carefully and slowly loosen the bolt where the hose joins the caliper, allow one or two drops to come out then tighten again. Be careful with this. The fluid will damage the paintwork on the frame if you let it get on it and you also don't want to let air back into the system, hence the reason you apply pressure to the lever.

If you can't get the pads apart at all have you tried to remove them, exposing the pistons. If you can do this then again you have to be extremely careful not to damage the pistons, I would only use a plastic tyre lever for this and even then probably wrap it in a cloth. Proceed at your own risk.

If all else fails..... back to your LBS

Good luck

I actually have quite a bit of pressure on the lever and just undo the bolt very carefully. Air in the system is extremely bad.

My original theory on why it happens was heat related - I first encountered it when I was partway through an 8 hour enduro, rolling down a hill and getting slower! The pads get closer and closer to the rotor, begin to drag, and eventually bite down hard.

The other time is happens is if I leave the bike alone for a while - say a week or two. The pads will usually be locked onto the rotor. Once I let out a little fluid, they'll be fine for hours.

A 20c or 50c piece usually wedges nicely between the pads too... Leave a few floating about in your backpack.

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