How to Install a Brake Slack Adjuster

Slack adjusters are used to adjust the amount of wear that brakes on a vehicle will be experiencing during application. Mostly used on heavy and medium sized trucks, slack adjusters can be easily installed if the right precautions are taken before installation. Maintenance of slack adjusters has been an issue among truck-owner circles too. Maintenance of slack adjusters can also be easily done for longevity and efficiency. This step-by-step guide will help you understand how slack adjusters can be installed onto your vehicle’s brakes and how they can be maintained. The tools and materials required for the job are given below.

Step 1 – Remove Retaining Mechanism

Your vehicle’s brakes come with a retaining mechanism. It is installed at the end of the brake cam shaft. To install the slack adjuster, first remove the retaining mechanism from the brake’s cam shaft. Use the mechanic’s kit for appropriate tools to remove the mechanism.

Step 2 – Install Slack Adjuster

To install the slack adjuster, first slide the adjuster on to the spline end of the brake cam shaft. When it has slid on completely, rotate the slack adjuster until it is secured into place. The trick is to make sure that the slack adjuster arm and its actuator push rod that helps close the adjuster on application of brakes is at a 90 degree angle. This angle should be maintained when the brakes are not applied. Make sure that the adjustment screw of the slack adjuster is only so tight so that there’s room for you to add grease.

Step 3 – Install Retaining Mechanism

After you have installed the slack adjuster onto the brake cam shaft, re-install the retaining mechanism on the end of the brake cam shaft. Make sure that it is a tight fit as it has to hold the slack adjuster into place at all times during brake operation.

Step 4 – Install Yoke Pin and Cotter Pin

These are parts of the assembly of the slack adjuster. The adjustment screw on the slack adjuster can be rotated. Rotate it to reveal the yoke pin hole. Line the yoke pin hole with the arm hole and install the yoke pin and the cotter pin into the mechanism.

Step 5 – Check Slack Adjustment

Now, after your installation is done, you have to check the adjustment of the slack adjuster. Do this by applying the brake. Use help from a friend for this. Your friend must apply the brake while you check the angle that the slack adjuster arm and the actuator push rod are making. This angle even on brake application should only be slightly higher than 90 degrees. Set all the slack adjusters to this angle.

Step 6 – Finishing the Job

It is recommended that slack adjusters be well lubed up at all times. Right after installation and adjusting the angles, apply generous amounts of grease to the slack adjuster mechanism. Make sure that after application, repeat the greasing procedure after every 25,000 miles have been driven using the same slack adjusters. This will help increase their longevity by reducing wear.