How to Bleed and Replace Brake Fluid on a 2008 Honda TRX500 Rubicon 4X4

Shop parts for a 2008 Honda TRX500RUBI ATV.

This MotoSport-exclusive guide covers a safe, complete procedure to replace and bleed the brake fluid on a 2008 Honda TRX500 Rubicon 4X4 (TRX500RUBI). Follow each step carefully and wear eye protection and gloves. Use only clean DOT 3 brake fluid unless you confirm a different spec in your service manual.

What you'll need

  • DOT 3 brake fluid (fresh, unopened)
  • Clear plastic tubing that fits snugly over the bleed nipples
  • Catch bottle for old fluid
  • Wrench set for bleed nipples and banjo/line fittings
  • Screwdriver or flat tool to open reservoir cap
  • Turkey baster or syringe (to remove old fluid from reservoirs)
  • Brake bleeder kit or one-way valve bleeder (optional but recommended)
  • Shop rags, gloves, and brake parts cleaner
  • Jackstands or ramps to lift wheels for access (if needed)

Model notes for the 2008 TRX500 Rubicon

  • The TRX500RUBI uses hydraulic disc brakes front and rear with separate master cylinder reservoirs. Keep the vehicle level when bleeding to avoid air pockets.
  • This model is 4X4 capable and heavier than smaller ATVs – support the machine securely before getting under it or removing wheels.
  • No factory ABS system to complicate bleeding, but some owners have aftermarket accessories near brake lines; inspect lines for chafing after years of use.
  • Corrosion on banjo bolts and copper crush washers is common on older machines — replace crush washers whenever you open a hydraulic line.

Preparation

  1. Park the ATV on level ground, engage parking brake or put vehicle in park, and disconnect the negative battery terminal to avoid accidental starts when working near electrical parts.
  2. Locate the brake fluid reservoirs. There is a front reservoir near the handlebar master cylinder and a rear reservoir associated with the rear master cylinder. Clean the area around caps to prevent contamination.
  3. Remove the caps and diaphragms and use a turkey baster or syringe to remove as much old fluid from each reservoir as possible.
  4. Top reservoirs with fresh DOT 3 fluid so the level is just below the filler lip. Keep caps loose but in place so you can monitor levels while bleeding.
  5. Inspect hoses, lines, and calipers for leaks, cracked hoses, or severely corroded fittings. Replace damaged components before proceeding.

General bleeding order & strategy

Bleed starting with the caliper farthest from the master cylinder, then the next farthest, finishing with the nearest. On the TRX500 Rubicon this typically means:

  1. Right front caliper
  2. Left front caliper
  3. Rear caliper

If your machine's master cylinder feed layout differs, follow the farthest-to-nearest rule. Keep the reservoir topped with fresh fluid throughout; never let it run dry.

Step-by-step bleed & fluid replacement

  1. Fit clear tubing over the caliper bleed nipple and submerge the other end into a catch bottle partially filled with clean brake fluid to prevent air draw-back.
  2. Have an assistant slowly depress the brake lever or pedal several times, then hold pressure. Open the bleed nipple about 1/4 turn until fluid and air bubble flow into the tube; close the nipple, then have the assistant release the lever. Repeat until fluid runs clean with no air bubbles.
  3. After each cycle, top the reservoir to maintain level. Do not let the master cylinder run dry or you will introduce more air into the system.
  4. Work through the bleeding order: right front, left front, then rear. For the rear, use the pedal and a helper in the same manner.
  5. If you have a one-way bleeder or vacuum pump, you can operate solo. Use vacuum or one-way devices per manufacturer instructions, still keeping reservoir topped.
  6. When fluid runs clear and free of air at each caliper, tighten bleed nipples to manufacturers' snug torque (hand tighten then a small fraction of a turn with a wrench). Replace any banjo bolt crush washers you removed during inspection and torque banjo bolts to proper spec if loosened.
  7. Clean all fittings and surrounding areas with brake cleaner. Reinstall reservoir diaphragms and caps. Wipe off any spilled brake fluid immediately — it will damage plastic and paint.
  8. Test brake lever and pedal firmness with the machine supported on stands and wheels off the ground. Brakes should feel firm and not spongy. If spongy, re-bleed the affected circuit until firm.

Final checks

  • Lower the ATV, perform slow-speed brake checks in a safe area. Confirm both front and rear braking performance under light loads before normal riding.
  • Dispose of old brake fluid per local hazardous-waste rules. Do not reuse or dump on ground.
  • Record the service date and fluid type in your maintenance log. Plan the next fluid change per your riding conditions & the owner's recommended interval — typically every 1-2 years for most ATVs under normal use.

Maintenance tips specific to the TRX500RUBI

  • Inspect and replace copper crush washers when opening hydraulic lines; they are inexpensive and prevent leaks.
  • Rubicon owners frequently ride in wet, muddy conditions – flush and replace fluid more often if you ride through water or deep mud because moisture accelerates fluid degradation.
  • Keep caliper sliding pins clean and lightly greased with a high-temperature brake lubricant to avoid uneven pad wear.
  • Check master cylinder reservoirs for signs of internal contamination or swollen rubber components — replace seals if you see debris or degraded rubber.

Performing a careful fluid replacement and bleed will restore braking performance and extend the life of the brake components on your 2008 TRX500 Rubicon. For OEM-quality replacement parts and consumables made to fit your exact model, visit the MotoSport parts page linked above.

Related Shopping Categories

Shop Brake Fluid for a 2008 Honda TRX500RUBI ATV.

Shop Brake Bleeders for a 2008 Honda TRX500RUBI ATV.

Shop Brake Pads for a 2008 Honda TRX500RUBI ATV.

Shop Brake Lines for a 2008 Honda TRX500RUBI ATV.

Shop Brake Tools for a 2008 Honda TRX500RUBI ATV.

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.