Technical Support - Hydraulic Brake Overhaul

Submitted by zack on Mon, 03/27/2017 - 15:56
A Bike Should Only Go as Fast as It Can Stop

Greetings, and welcome to the second installment of Technical Support, your comprehensive guide to what kind of voodoo it is that your mechanic is up to.  With the change in weather, you may notice some stiffness if your hydraulic brakes.  Systems expand in the heat, and things just don't quite feel the same.  Duly so, it was time to replace the innards in my brake lever (Sram DB5s).  This was the first time I'd done this procedure, but with an optimistic heart, and an open mind, I dove into the hydraulic brake overhaul.

The kit from Sram included a new plunger and spring (giving me the lever return that had worn over the months), along with a new bladder, just for funsies.  The circlip and washer provided keep the plunger and spring in the body of the brake.  The bladders can wear, but as luck would have it, my existing component was in pretty good shape.  I will never, ever complain about spare parts.  Fabulous.  Next, it was time to disembowel my brake.  Graphic content ahead.

My brake lever met its new guts.  How hard could it be?
The white plunger (new one shown) had deformed with heat and general use.  It was time to test Sram's engineers.  Notice the knolling.
Hydraulic Brake Overhaul Kit from SRAM
Have your gloves handy.  DOT fluid will leak all over the place, it will not be pretty.

Springs are widely regarded as the most reviled, vilified, and disparaged components to any greater mechanical system.  Truthfully, if you keep careful tabs on your springs, and dedicate the care and love that they demand in reinstalling the little devils, they can actually be quite agreeable.  Bear in mind, if one isn't seated correctly, or if it's bent, or if it's broken, you'll know almost immediately, then it's back to the drawing board.  Luckily, I only had to deal with two.  Now, to piece it all together.

Out with the old, in with the new.
I'll give you a few guesses as to which one is new.  Sram's minds reengineered the piston bit, slimmed it down, and extended the spring.

The old internals were, of course, filthy, and when it was fully reassembled, the brake had a whole new life to it.  The sluggish return of the lever turned into a lively snap, like that puppy from your youth, eager to play fetch.  What a joy.  There are home remedies for remedying a brake on its way out, but none of them beat all-new, Sram-certified internals, and nearly all of them are guaranteed to void your warranty, and could potentially invite more peril into your life than the usual amount us mountain bikers endure.

Not just a recommendation - a necessity.
Pray that mineral oil never mingles with these brakes, and in turn, pray that DOT fluid never finds its way into your Shimano brakes.  This is the kind of mistake you make but ONE TIME. 

Attach the refurbished brakes back onto your handlebars, and execute a final bleed to punctuate the process.  The older, garbage bits can go into the rubbish bin, and we can all get on with our lives.  Wasn't that fun?  I hope you learned something - I know I certainly did.  And please, before doing any of these procedures yourself, don't go into it blindly.  Consult with your LBS if you're unsure of any step, as it could save you money in the long run, and perhaps save you any costly medical expenses in the aftermath of brake failure.  It's our job, after all, to turn your money into working bikes.  Until next time, God bless and happy trail hunting!

Brand Reference