How to bleed SRAM hydraulic disc brakes
Bleed SRAM Level, Guide, G2 and Code brakes with DOT 5.1 using SRAM's two syringe method, with notes on Bleeding Edge versus older caliper ports and on SRAM's mineral oil Maven brakes.
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- Difficulty
- Difficult
- Time
- 45 to 90 minutes
SRAM hydraulic brakes show up on many mid and high end e-bikes. Most current SRAM brakes, including the Level, Guide, G2 and Code families, run on DOT 5.1 or DOT 4 fluid (SRAM support). This guide covers those DOT brakes using two syringes, one at the lever and one at the caliper, following Park Tool's write ups of SRAM's method (Park Tool, Bleeding Edge, Park Tool, older ports). For the general idea, see bleeding hydraulic disc brakes.
Brakes are safety critical. Never put mineral oil in a SRAM DOT brake, and never put DOT fluid in a mineral oil brake. SRAM says the wrong fluid can damage the system and make the brakes unsafe (SRAM bleed manual).
SRAM's Maven brakes are mineral oil brakes, not DOT (SRAM support). Their Bleeding Edge fitting is a Maven only size that fits SRAM's mineral oil kit (SRAM support). Don't use this DOT procedure on them.
DOT fluid irritates skin and eyes and damages paint. Wear gloves and eye protection, and wipe spills right away (Park Tool, SRAM bleed manual).
Bleeding Edge or older port
Look at the caliper bleed port before you start. SRAM lists three types: non Bleeding Edge, Bleeding Edge and threaded Bleeding Edge, each with its own steps (SRAM bleed manual). On a Bleeding Edge caliper you loosen the port with a 4 mm hex and snap the kit's Bleeding Edge adaptor onto it. On an older caliper you remove a bleed screw and thread the syringe in. The lever uses a T10 bleed screw either way (Park Tool, Park Tool).
What you need
- A DOT bleed kit with two syringes, bleed blocks and, for newer calipers, a Bleeding Edge adaptor, see brake bleed kit
- Fresh DOT 5.1, see DOT brake fluid
- Torx keys (T10), hex keys, a torque wrench and a brake pad spreader
- Isopropyl alcohol, rags, gloves and eye protection
Steps
These follow the Bleeding Edge version (Park Tool). Older ports connect differently at the caliper and run the fluid in a different order, so follow Park Tool's separate guide for them (Park Tool).
1Step 1
Turn the contact adjuster counterclockwise to its stop and note your reach setting. Park Tool sets flat bar levers with the tip 75 to 80 mm from the bar centerline for the bleed.
2Step 2
Remove the wheel, spread the pistons, remove the pads and fit a bleed block. Arrange the hose so it rises steadily from caliper to lever.
3Step 3
Fill the lever syringe about half to three quarters full and the caliper syringe about a quarter full, then push out all air and clamp each hose.
4Step 4
Remove the lever bleed screw and its O-ring with a T10 and thread the lever syringe in. At the caliper, open the Bleeding Edge port and snap the adaptor on.
5Step 5
Open the caliper port one turn and push most of the fluid from the lever syringe down into the caliper syringe. If the fluid there looks dirty, push it back, refill with fresh fluid and start again.
6Step 6
Gently pull back on the lever syringe to draw fluid and bubbles back up, without pulling so hard that air gets in past the syringes.
7Step 7
Close the caliper port, squeeze the lever a few times, then pull and push the lever syringe until few or no bubbles appear.
8Remove the lever syringe and fit the bleed screw
Park Tool torques it and the Bleeding Edge fitting to 1.5 to 1.7 Nm.
9Step 9
Clean everything with isopropyl alcohol, refit pads and wheel, reset your reach, and squeeze the lever to set the pads. Recenter the caliper if it rubs, see center a disc brake caliper.
Common mistakes
- Skipping the contact adjuster step. SRAM says a bleed done without setting pad contact fully out can let air in (SRAM troubleshooting).
- Mixing fluid types or sharing kits between DOT and mineral oil (Park Tool).
- Letting DOT fluid reach the pads or rotor. Contaminated pads lose power (SRAM bleed manual).
- Pouring old fluid down a drain. SRAM says dispose of it under local rules, never into drains, soil or water (SRAM bleed manual).
- Leaving it too long. SRAM recommends a bleed at least once a year, more often for heavy use (SRAM bleed manual).
Videos
When to get a pro
- You're not sure whether your brake is DOT or mineral oil.
- The lever still pulls to the bar after a bleed. SRAM dealers can bleed brakes for you (SRAM troubleshooting).
- A hose needs cutting or a new fitting, which needs a hose cutter and a rebleed (SRAM bleed manual).
- The brake lever carries a motor cutoff sensor and you can't confirm it still works. See check brake cutoff and throttle and when to call a pro.
Sources
- SRAM support, support.sram.com
- SRAM support, support.sram.com
- SRAM support, support.sram.com
- SRAM bleed manual, sram.com
- Park Tool, Bleeding Edge, parktool.com
- Park Tool, older ports, parktool.com
- SRAM troubleshooting, sram.com
- SRAM MTB: Bleeding Edge Brake Bleed, youtube.com
- How to Bleed Hydraulic Disc Brakes, SRAM Bleeding Edge, youtube.com
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