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  1. #1
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    Formula Oro: Rebuild or Replace?

    I have a set of Formula Oro K24's that I bought new 2 1/2 years ago (OEM take offs). They've been great until recently. I had problems that I thought were from a warped rotor, so I replaced the 160 with a 180 and got the Formula adapter, and put new pads on. Since then I've had a constant problem with the brake randomly rubbing badly, and it sings all the time. It's from the pads very lightly rubbing the rotor. It's not a true squeal, more of a high pitched hum that goes on and on through most of my ride unless I'm going through really rough terrain.

    I finally traced it down to the pistons not retracting much at all after I hit the brakes. On the rear, you can easily see the pads retract when you release the handle. On the front, they don't really retract at all that I can see. The wheel spins fairly freely, but the pads are very slightly rubbing the rotor. There's no clearance that I can see between the rotor and pads. I tried bending out the retraction spring, but that made no difference.

    I even tried putting zip ties around the rotor 'spokes' to dampen the sound, but that didn't work either.

    Tonight, I pulled the caliper, took rubbing alcohol and a pipe cleaner and scrubbed off the pistons as much as I could while they were fully out hoping that would help. Then I manually retracted them and expanded the pistons repeatedly while squirting in rubbing alcohol to hopefully scrub off any grit or grime that's not letting them retract. They don't retract any better.

    So I'm fed up. The question is, do I replace the front brake (rear works great), or try to rebuild it and hope it retracts properly after that? I know a rebuild would be much cheaper than a new brake, but I'm not 100% sure it'll work. Any thoughts on the feasibility of a rebuild?

    Any suggestions would be much appreciated. The brakes have been outstanding until recently. They still work great, but the noise is driving me nuts.

    If you suggest replacement, what cost effective equivalent would you recommend? I want just as good stopping power and modulation at a reasonable price. Any suggestions there? I like Formula, but if there's something better for less money, I'll go that route. Matching brakes don't really matter much to me. Power and modulation do.

  2. #2
    bt
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    toss em and get some new shimanos any flavor.

    thank me later

  3. #3
    Drinkin' the RIP9 Koolaid
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    I think I'm just tired of dealing with the Formula's. Ordered XT-M785, should be here by Monday. Not I just need to figure out which 180mm adapter to get for a Reba Team fork.

    If this doesn't turn out well, I'm coming after you bt....

  4. #4
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    Is the fork the newer post mount style? I just picked up the same setup, with the Shimano F180P/P2 adapter from JensonUSA. The front XT caliper should be 74mm post mount, which means you need to adapt from that to whatever your fork mount is.

  5. #5
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    K, I think your actions were appropriate for dealing with sticky pistons. I haven't had sticky pistons in a long time (so I would need to review), but I used to have that problem with brakes other than Formula.

    But, have you thoroughly bled them? 2 years is quite a while if you have used them a lot (e.g., you have one bike and ride a lot). I would think they need a bleed, or even flush with new fluid.

    I have K24s on my XC bike. I think they are about 4 years old now, and no problems (though I ride other bikes too). If I started having problems, I would clean and replace the fluid before I tossed them. But the XTs certainly have a good rep.

  6. #6
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    dnlwthrn, the fork is the 74mm post mount style, where the caliper will bolt directly to it with no adapter for 160mm rotors. For the180mm, I just need to space it directly out further with the spacer and longer bolts. It's not the side bolted type (IS I think).

    I bought the Formula adapter when I upgraded to 180mm, but I don't think it was faced correctly. I noticed that when I tightened down the caliper, it rotated in relation to the rotor. I tried spacing out the one side so it would tighten down and keep the pads parallel to the rotor, but never could get it right. Little annoyances like that are what made me decide to move on.

    The Formula brakes have worked flawlessly until now. I had another pair of K24's that I bought a couple years previously, and sold to a buddy of mine. He's still using them to this day with no problems. The move to the 180mm rotor seems to have precipitated all my problems with the brakes. I'm hoping the Shimano front will be a bit easier to dial in.

    ClydeCrash, I haven't bled the brakes because I haven't had any problems with mushy lever or anything like that. I'm not sure how old fluid would keep the calipers from retracting. The rears are the same age as the front and work just fine. I'm thinking that the extra heat in the front rotor/caliper from when it was a 160 may have cooked the front seals more than the rears. That was part of my reasoning for going to a 180mm rotor up front.

    Another advantage to going with the XT brakes is using mineral oil. I recently bled a set of older Shimano brakes with mineral oil, and it was super simple, and I didn't have to worry too much about getting the fluid on anything.

    I'm hoping it won't be too weird with the two different brake types on the bike. If it is, I'll just upgrade the rear to the XT M785 too since they are very reasonably priced.

    Thanks for the suggestions and help.

  7. #7
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    You need the same adapter I did. Brakes are going on this afternoon (I hope) so I'll let you know if I run into any alignment issues.

  8. #8
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    On ebay you can find K18's, front only for between $70 and $90 all day long, brand new.

    Also Chain Reaction Cycles has new sets of K24's for under $200, I just bought another pair. Best brakes I have ever used.

    Tom

  9. #9
    Barfed
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    DOT fluid expands over time as it soaks up moisture, so if you have not bled them in a while they are likely overfilled and that isn't letting the pistons fully retract.

  10. #10
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    Have a spare k24 caliper if you want it for parts

    Kaizmuth,

    I realize you already bought new brakes, but I have a used k24 front caliper that you could have for spare parts. I ran k24s for years and they are still my favorite brake (even compared to my current TheOnes). About a year ago I managed to snap the master cylinder right at the lever pivot of my front brake in a crash but the calipers are still good. I have been keeping the brake in my parts drawer ever since.

    It is yours for shipping costs plus $5 (just enough to get this lazy person off the couch). Note: I'll be open to pay for an ad to stay inline with any forum rules.

    -Nutball

  11. #11
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    Nutball, I appreciate it. I have all the parts I need for the M785 (including new rotor) that I'll be putting on tonight. I'm going to keep the K24 front and see if I can't figure out what's wrong with it and how to fix it. I don't like not knowing why it's not working properly. Now that I'm not dependent on it to ride, I can pull it apart and really dig into it.

    Boyslikedirt, I'm not sure that's it. I can manually retract the calipers fairly easily, they just don't retract at all on their own, even with the spring bent out some to try to aid things. I'll probably pull them apart, clean everything inside and out, put in new seals (if I can find them for a reasonable price) and put in all new fluid just to see what happens. Never hurts to have a good spare. With three working bikes, spares are a must.

    I do appreciate the ideas and suggestions. Thanks all.

  12. #12
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    If the pistons work like any other hydraulic brakes I've worked on, cleaning the visible part of the piston when it's extended helps little if anything. The cause of extra friction is deeper where it seals, and to really make the action smooth you need to remove the pistons entirely.

    My Oro K24's from CRC are waiting for me at the LPO, I'll know more about this particular brake set tomorrow when I get my hands on them. I've previously owned Avids.

  13. #13
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    I know you have bought new brakes, but I personally would give up on the Formulas, they are by far the best brakes i have ever used. I havent really taken care of them like i should and they still work flawlessly! i ride when its nasty out too. The modulation that these brakes have is pretty killer. i am going to send mine back to formulat when the time comes and have them rebuild them for me.

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