Bleeding the Hydraulic Brakes on a 2018 Triumph Speed Triple S

Shop parts for a 2018 Triumph Speed Triple S Motorcycle.

The 2018 Triumph Speed Triple S uses hydraulic disc brakes at both ends and is equipped with ABS. The front lever and rear pedal both move brake fluid through lines to the calipers, and the ABS unit is part of the hydraulic circuit. A standard bleed at the calipers is the correct way to refresh old fluid and remove air from the lines and calipers, but if air has entered the ABS unit itself, the job can require dealer-level equipment. This guide walks through a careful, methodical bleed for the Speed Triple S so you can complete the job at home when conditions are right and recognize when to stop.

When a Brake Bleed Is Due

Bleeding is not only for a brake system that has been opened for service. A spongy front lever, a pedal that feels longer or softer than usual, or a lever that pulls closer to the grip can all point to air in the system. Dark or cloudy fluid in the reservoir is another sign that the fluid is past its useful life. Brake fluid absorbs moisture over time, which lowers its boiling point and can lead to brake fade under hard or repeated use. Many riders refresh the fluid on a regular schedule even when the brakes still feel normal. A bleed is also required after installing new lines, servicing a caliper, or doing master cylinder work, because those jobs introduce air.

Tools and Supplies to Have Ready

  • Fresh brake fluid of the type marked on the master cylinder reservoir cap, from a sealed container
  • A box-end wrench that fits the bleeder valve
  • Clear tubing that fits snugly over the bleeder valve
  • A small catch bottle for used fluid
  • Rags or shop towels, plus water for rinsing spills
  • A syringe or turkey baster for removing old fluid from the reservoir
  • A screwdriver or driver that fits the reservoir cap screws

A one-way check-valve bleeder or a vacuum bleeder can make the job easier when working alone, but the manual lever-and-bleeder method works well if you follow the sequence carefully. Use only fresh fluid from a sealed container, and do not pour used fluid back into the system.

Preparation and Paint Protection

Support the Speed Triple S securely upright on a stand so the bike cannot tip while you are working. Turn the handlebars so the front master cylinder reservoir sits level before you open it. Cover the painted surfaces, plastics, and instrument area with rags, because most brake fluids damage paint and plastic on contact. If a spill happens, wipe it up immediately and rinse the area with water. Remove the reservoir cap and diaphragm, then use a syringe or turkey baster to take most of the old fluid out of the reservoir without letting it run dry. Refill with fresh fluid before you begin bleeding, and keep the reservoir partly filled throughout the job.

Bleeding the Front Brake

  1. Confirm the front reservoir is level and filled with fresh fluid, then fit the box-end wrench onto the front caliper bleeder valve.
  2. Push the clear tubing onto the bleeder and route the other end into the catch bottle so you can watch the fluid and bubbles.
  3. Squeeze the front lever slowly and hold it firm. Do not pump it rapidly or let it snap back.
  4. Open the bleeder about a quarter turn and let fluid and air travel out through the tube.
  5. Close the bleeder before you release the lever. This is the critical step that prevents air from being drawn back into the caliper.
  6. Release the lever slowly, then check the reservoir level and top it off with fresh fluid.
  7. Repeat the squeeze-hold-open-close-release sequence until clean, fresh fluid with no bubbles comes through the tube.
  8. If your bike has more than one front caliper, bleed them one at a time. Start with the caliper farthest from the master cylinder, then repeat the process on the other caliper.
  9. When the fluid runs clear and bubble-free, close the bleeder snugly without overtightening it, and check that the lever feels firm.

Bleeding the Rear Brake

  1. Check the rear reservoir level and top it off with fresh fluid of the type marked on the cap.
  2. Fit the box-end wrench and clear tubing onto the rear caliper bleeder valve, routing the tube into the catch bottle.
  3. Press the rear pedal slowly and hold it firm.
  4. Open the bleeder about a quarter turn to let fluid and air out.
  5. Close the bleeder before releasing the pedal.
  6. Release the pedal, then check and top off the rear reservoir.
  7. Repeat until the fluid in the tube is clean and free of bubbles, keeping the reservoir from running low.
  8. Close the rear bleeder snugly without overtightening it.

Finishing Up and Testing Before Riding

Fill the reservoir to the correct level marking, reinstall the diaphragm and cap, and clean any spilled fluid from the bike. Check for leaks at the bleeder valves and at the banjo fittings. The front lever and rear pedal should feel firm and consistent, not spongy, and they should not slowly sink under steady pressure. Spin each wheel to confirm the brakes are not dragging. Before riding normally, test the brakes at low speed in a safe area and make sure they engage smoothly and release completely.

When to Stop and Take the Speed Triple S to a Shop

If the lever or pedal will not firm up after several bleeding attempts, if it firms only after pumping, or if bubbles keep appearing, stop and have the bike inspected. Fluid leaking from the master cylinder or a caliper also needs professional attention. Because this Speed Triple S has ABS, any situation where the reservoir ran dry, the ABS unit was disturbed, or the lines were disconnected can allow air into the ABS unit. A standard caliper bleed may not remove that air, and the system may need a dealer-level procedure or diagnostic tool. Do not ride a motorcycle with questionable brake feel; have it checked before you head out.

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Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.