4

I have an SRAM Guide brake (rear) that after bleeding, the brake lever won't return quickly. At room temperature, this is barely noticeable, but when the temperature climbs, or the bike is in the direct sun, it takes about 30 seconds for the brake lever to return fully.
This happens every time I bleed it and lasts for at least a couple of weeks. The front brake, bled the same way, at the same time, has no issues. At first, I was thinking that there was too much fluid in system and when it got hot, the little bit of expansion would lock up the piston. However, when I popped the top bleed screw while hot, only a little bit of fluid came out and the lever was still sticky.
I am now wondering if the tolerances inside the lever are too tight. Once the barrel warms up, it shrinks enough that the spring can't overcome the friction... Any other ideas? Should I just give up and try a warranty return with SRAM?

  • Have you tried re-bleeding the system? – Batman May 6 '16 at 4:18
  • Yes, several times. I have disassembled the lever assembly and have confirmed that the plunger is sticking in the body. Guessing something foreign got caught in the system and bleeding pushed it towards the lever... – Scott Lundberg May 6 '16 at 4:26
  • I can think of a dozen reasons causing the lever to stick, but none that allow for a return to normal function without intervention in a couple of weeks. – zenbike May 9 '16 at 13:11
  • I disassembled the lever and found that the cup/seal closest to the hose sticks. I put some lube on it, and it's much better, though not as snappy as it should be. I think a new seal is probably the final solution. – Scott Lundberg May 9 '16 at 14:03
  • This seems to be a regular problem: forums.mtbr.com/brake-time/… We have two bikes w/ "stick" during hot weather and new Guide RS brakes. – user29176 Sep 7 '16 at 2:47
3

This is typically caused by seals which have become soft and sticky due to contaminates like degreaser. It also happens over time, and SRAM Elixir brakes are especially known to have this issue.

The Guide series hasn't been bad about this so far.

The solution is to replace all the seals in the lever. SRAM has a special grease (Avid DOT Grease) for this purpose, or you can use DOT 5.1 compatible grease. Regular grease will damage the seals.

enter image description here

  • 1
    This was a new lever that had nothing done to it. Since then, I have lubed it with non-dot grease just to get by until the new seal kit and dot grease come. I will re-post once I test that the new seals work. – Scott Lundberg May 12 '16 at 23:55
  • I disassembled and replaced the cup seals and plunger and lubed with the grease you suggested above. Works perfectly now! – Scott Lundberg Jun 3 '16 at 13:40
  • In case anyone else is having these problems and is unaware, there is a recognized defect in Guide levers. Heat causes the plunger to swell and not return. Pouring cold water on the body of the lever will fix this problem temporarily. SRAM is honoring warranties for this issue. – Joe Cullinan Sep 8 '17 at 18:43

protected by Community Sep 7 '16 at 16:08

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.