Fixing Loud Thump Noise When Shifting Transmission into Reverse: A Step-by-Step Guide

If you hear a loud thump noise when shifting your transmission into reverse, it can be concerning. This guide will walk you through diagnosing and fixing the issue, step by step. Please note that working on a transmission can be complex and potentially dangerous. If you are not confident in your ability to perform these steps, it's best to consult a professional mechanic.

Step 1: Gather the necessary tools and materials

Before starting any work on your vehicle, make sure you have the following tools and materials at your disposal:

  • Jack and jack stands
  • Wheel chocks
  • Wrench set
  • Screwdriver set
  • Transmission fluid
  • Drain pan
  • Shop rags
  • Protective gloves and eyewear

Step 2: Secure your vehicle

Park your vehicle on a level surface, engage the parking brake, and use wheel chocks to secure the front and rear wheels. Ensure that the vehicle is stable and secure before proceeding.

Step 3: Raise the vehicle

Use a jack to lift the rear of the vehicle, and place jack stands under the appropriate points to support the vehicle's weight. Lower the vehicle onto the jack stands and ensure it is stable before proceeding.

Step 4: Check for loose or damaged components

Inspect the transmission and its surrounding area for any loose or damaged components. Some common issues include:

  • Loose or damaged transmission mounts
  • Worn or damaged universal joints (U-joints)
  • Loose or damaged exhaust components

If you find any of these issues, they may be the cause of the thump noise. Repair or replace any damaged components as necessary.

Step 5: Check the transmission fluid

Low or contaminated transmission fluid can cause various issues, including a thump noise when shifting into reverse. Check your vehicle's owner's manual for the proper method to check the transmission fluid level and condition. If the fluid is low or appears dirty, it may need to be replaced.

Step 6: Drain and replace transmission fluid (if necessary)

If you determined that the transmission fluid needs to be replaced, follow these steps:

  1. Place a drain pan under the transmission.
  2. Remove the transmission drain plug and allow the fluid to drain into the pan.
  3. Once the fluid has drained, reinstall the drain plug and torque it to the manufacturer's specifications.
  4. Locate the transmission fill plug or dipstick, and add the recommended type of transmission fluid, as specified in your owner's manual.
  5. Check the fluid level according to the manufacturer's guidelines, ensuring that it is within the proper range.
  6. Start the vehicle and shift through all gears, including reverse, to circulate the new fluid. Recheck the fluid level and top off as necessary.

Step 7: Test drive the vehicle

After addressing any identified issues, lower the vehicle from the jack stands and remove the wheel chocks. Test drive the vehicle to see if the thump noise when shifting into reverse has been resolved. Pay close attention to any changes in the noise or other related symptoms.

Step 8: Consult a professional mechanic (if necessary)

If the thump noise persists after you've completed the previous steps, it's best to consult a professional mechanic. There may be more complex issues with your transmission or drivetrain that require specialized equipment and expertise to diagnose and repair.


A loud thump noise when shifting your transmission into reverse can be alarming, but by following this step-by-step guide, you can diagnose and fix the issue yourself. Remember, if you are not confident in your ability to perform these steps or the problem persists, it's always best to consult a professional mechanic.

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