My brakes suck!

Discussion in 'The Shop' started by teedubb, Jan 21, 2018.

  1. teedubb

    teedubb Chimp

    Rep/Likes:
    1 / 7
    Joined:
    Jan 16, 2018
    Messages:
    18
    Brand new bike with Deore m6000 front and rear hydro. Attempted to bed in as normal (clean rotors with alcohol, series of long slow & rapid stops). The rear has been squealing like a stuck pig straight out of the box. The rear struggles to lock up and the front as well.

    Took the pads off and cleaned them. No luck. Since it’s a new bike I’ll probably just bring it back to LBS and hope they messed something up on install. Any ideas before I do that?

    Pads are Shimano G02S
     
    #1 -   Jan 21, 2018
    Last edited: Jan 21, 2018

    Please register to disable this ad.

  2. StiHacka

    StiHacka Compensating for something

    Rep/Likes:
    301 / 2,820
    Joined:
    Jan 4, 2013
    Messages:
    9,355
    Location:
    i͓̽t͓̽ i͓̽s͓̽ fu͓̽l͓̽l͓̽ o͓̽f s͓̽t͓̽a͓̽r͓̽s͓̽
    How did you clean the pads? If they are contaminated, you just may have to get a new pair unless metallic and you can bake them at a high temperature. Bring it back to LBS and while waiting, entertain yourself with the excellent brakes threads in the DH forum. :monkeydance:
     
  3. teedubb

    teedubb Chimp

    Rep/Likes:
    1 / 7
    Joined:
    Jan 16, 2018
    Messages:
    18
    Some sand paper and wiped them down with a little alcohol. I’m not sure if the bike shipped with pads (I’d assume so) or if LBS put them on.
     
  4. rideit

    rideit Bob the Builder

    Rep/Likes:
    65 / 998
    Joined:
    Aug 24, 2004
    Messages:
    5,071
    Location:
    In the cleavage of the Tetons
    Yes, bikes ship with pads.
     
    • Useful Useful x 1
  5. Westy

    Westy the teste

    Rep/Likes:
    418 / 2,616
    Joined:
    Nov 22, 2002
    Messages:
    35,438
    Location:
    Sleazattle
    I've had luck breaking-in and decontaminating brakes by just getting the rotors good and muddy before exercising a few good stops. Fine silty mud or clay work the best.
     
    • Like Like x 1
  6. KenW449

    KenW449 something stupid

    Rep/Likes:
    22 / 172
    Joined:
    Jun 13, 2017
    Messages:
    1,797
    Location:
    Floating down the whiskey river...
    Go brakeless
     
    • Useful Useful x 1
  7. Jm_

    Jm_ Turbo Monkey

    Rep/Likes:
    136 / 889
    Joined:
    Jan 14, 2002
    Messages:
    7,745
    Location:
    AK
    The only consistent way I've been able to clean pads is bake the F-ers for about 15-20 min at 400 degrees.

    But, I don't recall having to "bed in" brakes like that since 1998 or so. The brake material will fill the gaps if you ride it and use the brakes. The more DH, the better.

    Turkey-warble vibration is due to resonant frequency and usually a function of the caliper-weight, frame-tubing and rotor, all allowing that vibration to get larger, the pads basically vibrate back and forth real fast and you get very little braking and the bike goes out of control. That usually isn't because of bedding.

    Normal squeal/screech usually goes away with hard braking IMO and getting some pad material on the rotor. If not, check for torsional aliment.
     
  8. canadmos

    canadmos Mater Slayer

    Rep/Likes:
    203 / 3,293
    Joined:
    May 29, 2011
    Messages:
    7,660
    Location:
    Canaderp
    I have those same brakes on my fat bike and if they are even slightest hint at being moist, they howl like crazy. However they have no problems locking up the wheels, especially the back. I'm guess they got contaminated somewhere along the way.
     
  9. Sandwich

    Sandwich just shake your rump
    Staff Member

    Rep/Likes:
    56 / 647
    Joined:
    May 23, 2002
    Messages:
    15,059
    Location:
    01776
    best way to bed in is to get to the top of a large hill, go as fast as you can, brake to about 5mph, accelerate and brake 5 more times. That gets a lot of heat into them, and should make them work. Most times I eff up my brakes, I could fix them by going really fast and cooking them with hard braking.

    Resin pads should be less warbly, but I guess you never know. You could buy new metal pads, use one pad of each (metal pads will also help power), or request new pads from the LBS. My guess is they won't give you any because LBSes are kind of dicks when it comes to "opinions".
     
  10. StiHacka

    StiHacka Compensating for something

    Rep/Likes:
    301 / 2,820
    Joined:
    Jan 4, 2013
    Messages:
    9,355
    Location:
    i͓̽t͓̽ i͓̽s͓̽ fu͓̽l͓̽l͓̽ o͓̽f s͓̽t͓̽a͓̽r͓̽s͓̽
    I have one rotor that when installed on a rear wheel on my crabon HT, it triggers real bad oscillations of the caliper/stay with an amplitude about 1/4". I could literally feel those vibration in my fingers on the handlebar and worried that the frame was going to crack under the stress.
     
  11. slimshady

    slimshady Turbo Monkey

    Rep/Likes:
    42 / 452
    Joined:
    Dec 20, 2007
    Messages:
    2,037
    Location:
    La Plata, Argentina
    @Udi has detailed in several threads how Shimano calipers tend to slowly leak fluid when the bike is sitting idle for a long time. I had a hard time getting a friend who was tired of changing contaminated pads to accept this very fact. But he finally settled for it and changed to Formulas.
     
  12. johnbryanpeters

    Rep/Likes:
    226 / 2,229
    Joined:
    Sep 27, 2001
    Messages:
    23,632
    Location:
    Making moss sad in New Haven, Vermont
    Could you or @Udi please point me at the most informative of these threads? The XTs on the Intense are getting to be about three years old...
     
  13. slimshady

    slimshady Turbo Monkey

    Rep/Likes:
    42 / 452
    Joined:
    Dec 20, 2007
    Messages:
    2,037
    Location:
    La Plata, Argentina
    This could be a good start IIRC.
     
    • Useful Useful x 1
  14. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

    Rep/Likes:
    87 / 732
    Joined:
    Mar 14, 2005
    Messages:
    4,633
    If you haven't spilt anything on your deore brakes, then the "cause" may be what's described below.

    The best commonly-available solvent to clean pads/rotors that have been oil-contaminated is acetone (100% pure) - it's chemically superior at dissolving oil than other common solvents (such as methylated spirits and isopropyl alcohol). Isopropyl is the 2nd best of those. It's important to ensure the solvent is pure, many store-bought solvents have other additives.

    Heat and mud riding (as per Jm and Westy) also help in my experience. It can be good to clean well (with whatever method) and retry so you can see if they come good and then recontaminate themselves later, which confirms the slow leak issue.

    In the frakenbrake thread there was an aftermarket solution posted if your Shimanos have been leaking (mysterious contamination that users blame themselves for is the usual symptom) in the form of an aftermarket piston and seal kit.

    It should fit most Shimano 2-piston brakes, need to purchase two to do one caliper. I have no personal experience but I'd rather try these than persevere with the known-bad genuine Shimano situation.

    https://www.ebay.com/itm/282489847007

    Some leak from brand new, some can go years without leaking, some develop leaks when left unridden.
    In any case, hopefully it's useful to someone.
     
    • Useful Useful x 2
    • Like Like x 1
  15. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

    Rep/Likes:
    87 / 732
    Joined:
    Mar 14, 2005
    Messages:
    4,633
    Goes without saying, if it's a brand new bike, just get them warrantied - someone should look after you.

    But for anyone with the same issue outside of warranty, I think it's wise to clean everything as much as possible and see if they get "good for a while then go bad again" to confirm the leaking caliper piston issue, and then address it how you see fit - rather than blaming yourself for contamination and buying new pads only to get re-contaminated endlessly.
     
    • Useful Useful x 1
  16. teedubb

    teedubb Chimp

    Rep/Likes:
    1 / 7
    Joined:
    Jan 16, 2018
    Messages:
    18
    Shop is replacing the pads. We’ll see.

    I had the Shimano m315’s (model below these) and they were great straight out of the box.
     
  17. Flo33

    Flo33 Monkey

    Rep/Likes:
    21 / 193
    Joined:
    Mar 3, 2015
    Messages:
    749
    Location:
    Styria
    This! I've been running BR-M785s for some years now, without any issues. LAst November they started to become spongy and I had to pump the rear lever some time - air inside. So I did my first bleed in like 3 years. All was good afterwards. At least for 3 rides, now the rear is spongy again and lacking power...

    Formula Curas ordered.
     
  18. FLIPTROP

    FLIPTROP Chimp

    Rep/Likes:
    0 / 0
    Joined:
    Mar 12, 2018
    Messages:
    5
    Hello, I recommend you clean the pistons with isopropyl alcohol and cotton swabs, with a modified bleed block, to allow one piston at a time to be cleaned and lubricated.
    First, push the pistons back, clean the caliper with isopropyl alcohol and reset the pistons with a reset tool or a plastic tire.
    Insert the modified bleed block, pull the lever until a piston comes in contact with the modified bleed block, then remove the BB-
    Clean the piston with isopropyl alcohol and cotton swabs and push back into the piston
    Reinsert the bleed block and pull the lever until the piston comes into contact with BB, and if it is still dirty repeat the cleaning process -
    once clean, apply a few drops of shimano mineral oil and push it back in.
    Clean again with isopropyl alcohol and repeat the procedure for the second piston.
    After cleaning the system, bleed the brake, with gravity system and vertical caliper, changing all the mineral oil.
    Your brake will be perfect

    PS:
    Cura is a very good brake
     
    #18 -   Mar 12, 2018
    Last edited: Mar 12, 2018
  19. StiHacka

    StiHacka Compensating for something

    Rep/Likes:
    301 / 2,820
    Joined:
    Jan 4, 2013
    Messages:
    9,355
    Location:
    i͓̽t͓̽ i͓̽s͓̽ fu͓̽l͓̽l͓̽ o͓̽f s͓̽t͓̽a͓̽r͓̽s͓̽
    Here's how I fix Shimano calipers:
     
  20. Flo33

    Flo33 Monkey

    Rep/Likes:
    21 / 193
    Joined:
    Mar 3, 2015
    Messages:
    749
    Location:
    Styria
    R0 Racings are installed already.

    My XT 785 developed another strange behavior right before the swap. When I pulled the rear lever in a normal speed it felt realtively normal, spongy because of air, but otherwise normal. When I pulled it at a slow speed I was able to pull it all the way to the bar. It was worse when I released the tension a bit an then continued to pull slowly. Whenever pulled at normal speed - no problem. Brake pads are ok, caliper is clean, did a bleed with thorough cleaning 3 rides ago. The bleed was good I think, because the last ride was a long 3 hr nonstop up and down again on some hard and steep trails, no problems. Biting point was relatively consistent.

    Any ideas or thoughts? I'm guessing MC seal failure. But I don't care enough to swap levers.
     
  21. FLIPTROP

    FLIPTROP Chimp

    Rep/Likes:
    0 / 0
    Joined:
    Mar 12, 2018
    Messages:
    5
    Hi
    For rear brake , bleed must be done with caliper in vertical position, because if the caliper is in this position
    upload_2018-3-13_23-14-46.jpeg


    air bubble can get trapped at the top of caliper
     
  22. Flo33

    Flo33 Monkey

    Rep/Likes:
    21 / 193
    Joined:
    Mar 3, 2015
    Messages:
    749
    Location:
    Styria
    The whole brake was taken off the bike and caliper was dangling freely down vertical.
     
  23. FLIPTROP

    FLIPTROP Chimp

    Rep/Likes:
    0 / 0
    Joined:
    Mar 12, 2018
    Messages:
    5
    Are you sure?
    You have change all mineral oil ?
    You have change with gravity system?
    Because if you push oil to caliper vs pump, when oil is exaust and dirt, is not correct, correct is viceversa, dark dirt flush must out trougth the caliper.
    Dirt oil makes system spongy
     
  24. valve bouncer

    valve bouncer Master Dildoist

    Rep/Likes:
    8 / 15
    Joined:
    Feb 11, 2002
    Messages:
    7,820
    Location:
    Japan
    This is great stuff Udi thanks so much. Got my eye on some first gen SLX with a leaking rear caliper in the auctions, seems this might be a way to sort them. At the very least a cheap and easy fettle, if I do it I'll update this thread with the relevant info.
     
    • Like Like x 1