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SRAM Guides locking up

yorkiedaveyorkiedave Posts: 17
edited May 2019 in MTB workshop & tech
I have a Boardman Pro 29er with SRAM Guide brakes. I went out today and the front brake locked on and wouldn't release. I managed to part the pads manually so i could continue. The back brake also appeared a little sticky on too.

Had the bike since October 2016 and never had this happen before.

Any ideas what this might be and how I can fix it?

Thanks.

Posts

  • The RookieThe Rookie Posts: 27,747
    Common issue with SRAM, if they are overfilled the fluid warms and expands and locks on, you need to open the bleed screw on the lever and allow a little to self bleed out.
  • have they ever been bled? Is this the original fluid?
  • have they ever been bled? Is this the original fluid?

    No I've never bled them might try this as a first step.

    Any recommendations for bleed kits?
  • Old fluid absorbs moisture so it behaves differently causing the lock img up.

    Avid's own kit is nice but pricey, best if you are going to do several brakes regularly.
    Theres plenty of aftermarket kits but you need one for SRAM/Avid as it uses 2 syringes that hve to lock off.

    Otherwise £30ish for a shop to do it
  • steve_sordysteve_sordy Posts: 1,996
    Try these people.Epic Bleed Solutions. They have "how to" videos and they sell the kits too. They specialise in brake bleeding and the kits required. You get the correct fluid and all the kit required. You can use them multiple times.

    https://www.epicbleedsolutions.com/products/bleed-kits/
  • billycoolbillycool Posts: 833
    I used an Epic bleed kit when I had my J5's. Seemed to do a good enough job (the brakes are still a PITA to bleed).
    "Ride, crash, replace"
  • The RookieThe Rookie Posts: 27,747
    Old fluid absorbs moisture so it behaves differently causing the lock img up.
    Two issue with that
    1/ It shouldn't be absorbing water in a sealed system, its not like (most) car systems which are open to atmosphere
    2/ Until it gets to quite a high water content absorbing water reduces volume as the hygroscopic nature means the molecules are pulled in closer by the water molecules (same way dissolving salt or sugar in water reduces it's volume) and thus reducing the chance of a lock up.
  • compuwiz_ukcompuwiz_uk Posts: 139
    yorkiedave wrote:
    I have a Boardman Pro 29er with SRAM Guide brakes. I went out today and the front brake locked on and wouldn't release. I managed to part the pads manually so i could continue. The back brake also appeared a little sticky on too.

    Had the bike since October 2016 and never had this happen before.

    Any ideas what this might be and how I can fix it?

    Thanks.

    seems like its the time of year for this happening.

    my 2016 Boardman FS Pro bought in May/June 16 is currently in having its guides looked at as i pulled it out of storage last week & the 1st time i pulled the rear brake to stop the bike ( so i could put the other bikes away again ) the lever went to the bars & stayed there & the front brake was beginning to show signs of sticking too :(

    they have basically tried bleeding em, flushing em, but the piston inside the lever appear to be sticking inside the lever no matter what they do ( removed/cleaned/applied sram goop meant for lubing the brake seals etc ) & thus they have declared them FUBAR'd :cry:

    now at nearly 3 years old they are out of the 2 year SRAM warranty ( the store looked that up before declaring them toast ) which is most annoying seen as the bike has less than 270 miles on it in total ( so very light use ) tend to use the other bikes in the fleet more as the full sus for the work commute seems like overkill really - HT or CX take the brunt of the commute duties.

    a quick google since hearing that they were goosed has shown this is sadly a very common problem ( mostly appearing late 2016 it seems ) leading to some folks replacing them with other brands & giving the guides a flaming funeral once removed from the bike, to others having a tinker & slightly sanding down the piston/plunger thats inside the lever to make it smaller so it no longer gets stuck inside the lever & thus bringing the brakes back to life.

    i am kinda between the 2 at the minute as i have a pair of Shimano M8020 brake kits on the way for the FS Pro ( wanted to keep the 4-pot aspect of the guides - also the M8020's seem to use the same pads as one of my other bikes does so i already have spares :D ) but i intend to keep the guides & have a tinker with them ( either by sanding down the plastic piston inside or by fitting an aftermarket alloy piston so the fecker no longer expands in hot weather or when its had enough of the DOT brake fluid the guides use :( - if i manage to revive the guides i will bung em on my fat bike thats currently sporting a lovely pair of Shimano BR-M355's ( they work well enough but guides should be better when they be working for such a hefty bike - will also mean i can hopefully get the spare pads i have for the guides used too :lol: )
  • i intend to keep the guides & have a tinker with them ( either by sanding down the plastic piston inside or by fitting an aftermarket alloy piston so the fecker no longer expands in hot weather or when its had enough of the DOT brake fluid the guides use :( - if i manage to revive the guides i will bung em on my fat bike thats currently sporting a lovely pair of Shimano BR-M355's ( they work well enough but guides should be better when they be working for such a hefty bike - will also mean i can hopefully get the spare pads i have for the guides used too :lol: )

    if you sand them down you only need to do the section between the 2 rubber seals, thats the bit that drags
  • compuwiz_ukcompuwiz_uk Posts: 139
    i intend to keep the guides & have a tinker with them ( either by sanding down the plastic piston inside or by fitting an aftermarket alloy piston so the fecker no longer expands in hot weather or when its had enough of the DOT brake fluid the guides use :( - if i manage to revive the guides i will bung em on my fat bike thats currently sporting a lovely pair of Shimano BR-M355's ( they work well enough but guides should be better when they be working for such a hefty bike - will also mean i can hopefully get the spare pads i have for the guides used too :lol: )

    if you sand them down you only need to do the section between the 2 rubber seals, thats the bit that drags

    will keep that in mind as plan B, got a pair of alloy replacement pistons ordered last night as plan A :D ( less than £14 for 2 pistons on ebay so worth a punt )

    now on a lighter note, anybody want to place a bet on how long it takes me to go O.T.B when i next ride the boardman when it comes back from having the brakes done - M8020's & disks upped from 180/160 to 203/180 - the guys working on the bike expect it within the 1st 30 minutes :lol:
  • SkonkSkonk Posts: 364
    This happened to my Guide RS brakes a couple of weeks ago.

    Been off the bike for a couple of years and getting back into it again; went out on a hot day and the front locked on.

    I stripped the levers down, took the pistons out, covered the seals in tape to protect them and then I carefully filed down the plastic areas that were binding (periodically checking the fit) and then re-assembled them.

    They've run perfect ever since; perhaps even the best they have ever been.
    Canyon Spectral AL 9.0 EX
    Planet X RT90 Ultegra Di2
  • foo606foo606 Posts: 113
    Ive had same problem with my Guide r rear From day 1 .Total lock up on rear 20 mile into a ride made it hard as it was binding all the time .
    Im removing them and changing to ultimates .
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