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Disc Brake Woes

So my new-to-me winter bike uses a set of Juicy 7s. Despite the mild winter, I've taken every opportunity to ride it in the snow, ice and rain that we have had this winter.


The disc brakes have me super frustrated. The pistons simply will not move freely back into the calipers (both front and back), and it is at a point where the bike is unrideable due to rotor rub.


I've tried pulling the pads, extending the pistons and cleaning them really well with rubbing alcohol. It seems to help a tiny bit, but once the pads are back in they go back to their previous ways.


Any suggestions? Would a bleed resolve this? Servicing the calipers with new seals? putting a quarter of what I paid for the whole bike into brake maintenance leaves me kind of beside myself.


As it is a new bike to me, I've been somewhat anal about keeping the bike clean. That said, I never thought to pull the pads and clean the pistons after every sloppy ride. My car has disc brakes front and back and they get used in inclement weather and sit outside all the time.


dmtroyer
2012-03-06 18:46:07

I've had plenty of car and motorcycle calipers do the same thing over the years. I doubt that bleeding, in and of itself, would make a difference.


It sounds like your pistons are corroded, which causes friction/interference with the seals. You may be able to pull the pistons out of the caliper, remove the corrosion with very fine sandpaper, install new seals (or maybe the old ones), and put them back together (and change the fluid in the process).


The difference with your car brakes is, in my opinion, that they get hot enough in regular use to evaporate most of the moisture, and they are pretty well shielded in any case.


If it's otherwise practical, using an air compressor to blow out the moisture after riding in the rain, etc. is a decent way to ward off this problem. The same is true with chains. I've done so, with good results, on all kinds of bikes and other equipment. Also, the Avid bleed kit works pretty well.


jmccrea
2012-03-06 19:19:10

Agree with the above. Car and MC brake calipers have a rubber bellows that moves in and out with the piston, if you get a cut or tear in the rubber you can be fkd in pretty short order. Don't know if bike disks have a similar setup.

Simply extending the pistons to clean them probably wouldn't do it, you would need to pull the piston out completely and clean the piston and cylinder.


edmonds59
2012-03-06 19:40:10

I guess I should be thankful that while I was living/commuting in Seattle they refused to ever drop road salt.


I completely agree with Jacob McCrea, but what a a pain in the ass to have to do all that. :(

You might just want to do what I do with my car and keep an extra set of calipers around to swap out when problems turn up; at least that way, you can get to it when you get to it.


headloss
2012-03-06 22:31:22

You could get some mechanical discs for the winter. Would solve most of your problem.


Be careful with those brakes. They use DOT fluid which is corrosive. It'll burn your skin and remove paint.


mayhew
2012-03-06 22:34:23

@Chris yeah, I'm thinking the same thing, kind of wish I would have picked up those BB7s that surfaced on clist a few weeks ago. I'll make sure to refresh the box of nitrile gloves before I go taking things apart.


Probably should have stayed away from the car analogy, was just trying to communicate my surprise and disappointment.


dmtroyer
2012-03-07 03:08:14

send them to sram as a warranty return. they'll most likey just send you new ones, or new elixirs since they discontinued the juicy line. their customer service is amazing.


cburch
2012-03-09 02:31:37

ummm, not OT at all. why would anyone in their right mind want to subject themselves to the temperamental pain in the ass that are hydraulic disc brakes when a nice set of rim center pulls would do just fine?


dmtroyer
2012-03-11 04:03:45

^^ Not that his article is totally invalid, but he did the #1 thing everyone tells you NOT to do, which is drag your brakes. He also picked one the lightest rotors on the market...


rice-rocket
2012-03-11 15:54:03

Well, going down on long unfamiliar windy road on a road bike you don't have much of a choice but apply breaks for a lot of times. Basically locking them. And nobody wants big rotors on a road bike. Just an example -- yesterday I went for a ride with PMTCC and there a couple of down hills where I got easily to speed in excess of 45 mph (with my weight it's pretty easy to do -- 250 :) -- plus bike, bottle, clothes, etc). 130 was OK but on other hills I had to basically lock my breaks since there were a couple of traffic lights and I did not want to approach a red light and not to be able to stop. I think I would boil those breaks also.


2012-03-12 18:07:44

the top two causes of problems with disc brakes are improper bleeds and contaminated pads/rotors. if people would take the time to set them up right in the first place they would be good to go for years. the whole point of disc breaks is that once set up they are much much more powerful with way less upkeep.


cburch
2012-03-12 22:34:53

"with way less upkeep."


Unless a) the caliper has a design flaw which causes them to leak an thus contaminate the pads or b) you take the wheel off and forget to use a spacer to prevent resetting the pads/pistons.


headloss
2012-03-12 23:06:23

Resetting pads and pistons is not the trauma it used to be. If you have a bleed kit (which you should, it's easy to do and makes a huge difference) or bought the brakes after market they come with a plastic spacer. Shove that puppy in there squeeze the lever a couple times. Replace wheel and squeeze again. If your caliper leaks you should warranty it that's not a design flaw, that's a broken caliper.


cburch
2012-03-13 14:33:23