Troubleshooting Shimano BR-R9170 Disc Brakes: How to Fix Common Braking Issues

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The Shimano BR-R9170 [paid link] disc brake system is a high-performance choice for road cyclists, offering reliable stopping power, smooth modulation, and precise control. However, like any braking system, it can experience issues that impact its efficiency and performance. Understanding how to troubleshoot common braking issues with your Shimano BR-R9170 [paid link] disc brakes is essential for keeping your bike safe and performing at its best.

Common Braking Issues with Shimano BR-R9170 Disc Brakes

1. Spongy or Soft Brake Lever Feel

A spongy or soft brake lever feel is one of the most frequent issues encountered with hydraulic disc brakes like the Shimano BR-R9170 [paid link]. This issue often results from air trapped in the hydraulic lines, causing a lack of brake responsiveness.

Causes:

  • Air bubbles in the brake lines.
  • Insufficient brake fluid.
  • Leaking hydraulic lines or connectors.

Solution:
To fix a spongy lever feel, you need to bleed the brakes. Bleeding removes air from the brake lines and ensures the hydraulic system is filled with the appropriate amount of fluid.

Steps to Bleed Shimano BR-R9170 Brakes:

  • Step 1: Position your bike on a workstand to ensure the brake levers are horizontal.
  • Step 2: Remove the brake caliper and the wheel to access the brake pads.
  • Step 3: Attach the Shimano bleed kit [paid link] to the brake lever and caliper.
  • Step 4: Open the bleed valve on the caliper and slowly pump the brake lever to release the air and old fluid.
  • Step 5: Keep topping up the brake fluid as you continue the process to prevent air from entering the lines.
  • Step 6: Close the bleed valve once all the air has been removed and fresh fluid is coming through.
  • Step 7: Reassemble the brake system, ensuring everything is properly secured.

After bleeding, check the brake lever feel. It should feel firm and responsive.

2. Noisy Brakes (Squealing or Grinding Sounds)

Brakes that make excessive noise, such as squealing or grinding, can be a sign of several potential issues, including misalignment, contamination, or worn-out pads.

Causes:

  • Contaminated brake pads or rotor surface (oil, dirt, etc.).
  • Misaligned brake pads or rotors.
  • Worn-out brake pads.
  • Glazed brake pads or rotor surface.

Solution:
Start by cleaning the rotor and brake pads thoroughly. If contamination persists, it may be necessary to replace the brake pads.

Steps to Clean the Brake Pads and Rotor:

  • Step 1: Remove the brake pads and clean them with rubbing alcohol or a suitable degreaser.
  • Step 2: Clean the brake rotor with rubbing alcohol or a dedicated brake cleaner.
  • Step 3: Reinstall the pads after they have dried completely.
  • Step 4: If the squealing continues, lightly sand the surface of the brake pads and rotor with fine-grit sandpaper to remove any glaze that might have built up.

If noise persists after cleaning, it could be a sign that the pads are worn out and need replacing.

3. Uneven Brake Pad Wear

Uneven wear of brake pads can affect the braking performance of your Shimano BR-R9170. If one side of the brake pad is more worn than the other, it may indicate misalignment of the caliper or an issue with the rotor.

Causes:

  • Misaligned brake caliper.
  • Rotor warping or damage.
  • Contaminated or improperly installed brake pads.

Solution:
Start by inspecting the alignment of the caliper. If it’s misaligned, you will need to adjust it. Additionally, check the rotor for warping, which can cause uneven pad wear.

Steps to Adjust Caliper Alignment:

  • Step 1: Loosen the caliper mounting bolts slightly.
  • Step 2: Center the caliper over the rotor by eye and tighten the bolts to secure the caliper in place.
  • Step 3: Check the alignment of the brake pads. If they are uneven, make further adjustments to the caliper.
  • Step 4: If rotor warping is suspected, consider replacing the rotor to ensure even braking and optimal performance.

4. Brake Fade or Loss of Stopping Power

Brake fade occurs when the brake system loses its stopping power after prolonged use, especially during long descents or when braking heavily. This is often caused by overheated brake fluid or worn-out brake pads.

Causes:

  • Overheated brake pads or fluid.
  • Worn-out brake pads.
  • Contaminated brake pads.

Solution:
The solution to brake fade depends on the underlying cause. If the brake pads are worn out or contaminated, replace them. If the brake fluid has overheated, perform a brake fluid change to restore the braking power.

Steps to Replace Brake Pads:

  • Step 1: Remove the wheel and locate the brake pads in the caliper.
  • Step 2: Remove the retaining pin or bolt holding the pads in place.
  • Step 3: Replace the old pads with new ones, ensuring they are correctly oriented.
  • Step 4: Reinstall the wheel and check the brake lever feel for proper engagement.

5. Brake Rotor Warping

Rotor warping is another issue that can affect the performance of your Shimano BR-R9170 disc brakes. A warped rotor may cause inconsistent braking, often accompanied by a pulsing sensation in the brake lever.

Causes:

  • Overheating of the rotor due to extended heavy braking.
  • Impact damage from rocks or debris.
  • Improper installation of the rotor.

Solution:
In some cases, minor rotor warping can be corrected by gently bending the rotor back into shape using a rotor truing tool. If the warping is severe, however, you will need to replace the rotor entirely.

Steps to True a Rotor:

  • Step 1: Remove the wheel and brake caliper.
  • Step 2: Secure the rotor in a truing stand or using the bike frame as a guide.
  • Step 3: Carefully use a rotor truing tool to bend the rotor back into alignment.
  • Step 4: Reinstall the brake system and check for smooth braking action.

6. Brake Levers Not Engaging or Failing to Return

If the brake lever fails to engage or doesn’t return to its normal position after being pulled, it may indicate an issue with the hydraulic system or the lever itself.

Causes:

  • Air in the hydraulic lines.
  • Leaking hydraulic fluid.
  • Faulty brake lever mechanism.

Solution:
The first step is to check for hydraulic leaks. If there is a leak, you will need to address it by replacing damaged components. If there are no leaks, bleed the brakes to remove air from the system.

Conclusion
Proper troubleshooting of your Shimano BR-R9170 disc brakes can ensure that you maintain optimal braking performance and extend the lifespan of your braking system. By following the steps outlined above, you can address common issues such as spongy brake levers, noisy brakes, and uneven pad wear. Regular maintenance, including bleeding the brakes, cleaning components, and replacing worn-out parts, will keep your Shimano BR-R9170 disc brakes working like new, providing you with reliable stopping power on every ride.