How to Install, Adjust, and Maintain the Shimano BR-RS405 Disc Brakes

Posted on
in No category

The Shimano BR-RS405 [paid link] is a hydraulic disc brake caliper designed for road bikes. It offers reliable stopping power and smooth modulation, making it a popular choice for cyclists upgrading from mechanical disc brakes. However, proper installation, adjustment, and maintenance are crucial to ensure peak performance and longevity.

This guide will cover everything you need to know, from installing your Shimano BR-RS405 [paid link] brakes to troubleshooting common issues and maintaining them for long-term reliability.

Tools Required

Before you begin, gather the following tools:

  • 5mm Allen key
  • Torx T25 wrench
  • Shimano hydraulic mineral oil [paid link]
  • Bleed kit [paid link] (funnel, syringe, tubing)
  • Rotor truing tool
  • Isopropyl alcohol (for cleaning)
  • Clean, lint-free cloth
  • Torque wrench [paid link]

1. Installing the Shimano BR-RS405 Disc Brakes

Proper installation is key to ensuring safe and efficient braking performance. Follow these steps carefully:

1.1 Mounting the Brake Caliper

  1. Align the BR-RS405 [paid link] caliper with the brake mounts on the frame or fork.
  2. Insert the bolts and tighten them loosely using a 5mm Allen key.
  3. If needed, install the appropriate caliper adapter to match your rotor size (140mm or 160mm).

1.2 Installing the Brake Rotor

  1. If using a Center Lock rotor, tighten the lockring with a T25 Torx wrench [paid link].
  2. If using a 6-bolt rotor, tighten each bolt evenly in a star pattern to ensure even pressure.
  3. Check for rotor clearance by spinning the wheel—ensure the rotor doesn’t rub against the brake caliper.

1.3 Attaching the Hydraulic Brake Hose

  1. Insert the hydraulic hose into the caliper and secure it using a hose connector bolt.
  2. Tighten the bolt to 5-7 Nm using a torque wrench [paid link].
  3. If shortening the hose, use Shimano’s SM-BH59/SM-BH90 cutting tool to make a clean cut before inserting a new olive and barb.

2. Adjusting the Shimano BR-RS405 Brakes

Once installed, adjustments are necessary for optimal braking performance.

2.1 Centering the Brake Caliper

  1. Loosen the caliper mounting bolts slightly so the caliper can move.
  2. Squeeze the brake lever to align the caliper with the rotor.
  3. While holding the lever, tighten the caliper bolts evenly to 6-8 Nm.
  4. Spin the wheel to check for rotor rub—re-adjust if necessary.

2.2 Setting Brake Pad Clearance

  1. Pull the brake lever multiple times to reset the pistons.
  2. If the pads rub against the rotor, use a 2mm Allen key to adjust the pad clearance screw.

2.3 Lever Reach Adjustment

  1. Locate the reach adjustment screw near the brake lever.
  2. Turn clockwise to bring the lever closer, or counterclockwise to extend it.

3. Maintaining the Shimano BR-RS405 Disc Brakes

Regular maintenance prevents premature wear and keeps your brakes performing at their best.

3.1 Cleaning the Brake Rotors and Pads

  1. Wipe the rotor surface with isopropyl alcohol to remove oil and contaminants.
  2. If braking power feels weak, sand the brake pads lightly with fine-grit sandpaper.
  3. Avoid touching the rotor or pads with bare hands to prevent contamination.

3.2 Checking for Brake Pad Wear

  1. Remove the wheel to inspect pad thickness.
  2. Replace pads if the friction material is less than 1mm thick.
  3. Always use genuine Shimano pads (L02A, L03A, or K02S models) for compatibility.

3.3 Bleeding the Hydraulic System

If braking feels spongy or inconsistent, air may be in the system. Bleeding removes air bubbles and restores firmness.

  1. Attach the Shimano SM-DISC-BP bleeding funnel to the reservoir.
  2. Open the bleed port and slowly push fresh mineral oil [paid link] through the system.
  3. Close the bleed port and remove any excess oil.
  4. Test the brake lever feel—repeat the process if necessary.

4. Troubleshooting Common Issues

4.1 Brake Noise or Squealing

  • Ensure rotors and pads are completely clean.
  • Check that the caliper is properly centered.
  • Sand down glazed brake pads and re-bed them by braking hard 10-15 times.

4.2 Weak or Spongy Braking

  • Bleed the brakes to remove air bubbles.
  • Check for leaks in the hydraulic hose.
  • Ensure the brake pads have sufficient material left.

4.3 Rotor Rubbing

  • Loosen and realign the caliper.
  • True a bent rotor using a rotor truing tool.
  • Verify that the wheel is fully seated in the dropouts.

5. Optimizing Performance for Better Braking

  1. Upgrade to finned brake pads (like Shimano L03A) to improve cooling and reduce fade.
  2. Use larger rotors (going from 140mm to 160mm) for increased stopping power.
  3. Ensure proper bedding-in by braking progressively during the first few rides.

6. Comparison with Other Models

The Shimano BR-RS405 is often compared to the Shimano BR-RS505 and BR-RS805. While all use hydraulic actuation, the RS405 is positioned as a mid-range option with good performance at a reasonable price.

FAQs

1. How often should I bleed my Shimano BR-RS405 brakes?
Shimano recommends bleeding hydraulic brakes once per year or anytime the lever feels spongy.

2. Can I upgrade my Shimano BR-RS405 brakes to a higher model?
Yes, but you’ll need to check compatibility with your brake levers and frame mounts.

3. What brake pads are compatible with the BR-RS405?
Compatible options include Shimano L02A, L03A, K02S, and K03S pads.

4. How do I stop my Shimano BR-RS405 brakes from squealing?
Clean the rotors and pads, realign the caliper, and ensure proper bedding-in.

5. What rotor size should I use with the BR-RS405?
The BR-RS405 is compatible with 140mm and 160mm rotors.

6. Can I use different brake fluid with Shimano BR-RS405?
No, always use Shimano mineral oil [paid link]—other fluids can damage the seals.