Must Have Tractor Trailer Alignment Tools

You must have all of the proper trailer alignment tools to perform a proper alignment. Shop safety is top priority when performing trailer maintenance. A level parking area free from clutter is paramount. A trailer alignment will go much more smoothly if you take the time to set up your work area and gather all of the required tools before beginning a trailer alignment.

Axle Extensions

axle extension bazooka tubes

The best trailer alignment tools are bazooka tubes. They screw directly onto the threads on the end of an axle. Test results show that with this method you can achieve more consistent repeatable measurements. Another words screw on axle extensions, or bazooka tubes are more accurate. Trailer axles are available in both straight axle ends and tapered axle ends. Be sure you have the correct bazooka tubes for your axle ends.

If your semi-trailers are on oil, you will also need to replace the axle hubs oil with new oil and replace the hub cap gasket with a new one. This is an excellent time to perform another task of trailer maintenance. You can check the run out on the wheel ends to see how the bearings and races are doing in the axle hub. This should add less than 15 minutes to the trailer alignment if the trailer mechanic is prepared. It could save you thousands of dollars by not burning up one wheel end.

Another trailer alignment tool is an axle extension that mounts on to the rim. I tried these in one of my shops. Mostly with marginal success. Some of the issues were mechanic related, but most inaccuracies were related to the tool. You must be extra vigilant when installing this type of axle extensions on the rim. You install this type of axle extension by mounting the apparatus directly over the center of the axle tube. The exact center of the axle tube has a dimple that must be perfectly lined up with the axle extension. The reason this type of axle extension is not my first choice of an alignment tool is that axles are capped with a welch plug. This makes the axle easy to adapt the axle for other accessories like tire inflation systems. While the plug is installed by a machine rather than by a human, you still run across un-centered plugs. This means the dimple you are using to center the axle extension is off center. This will create an out of alignment trailer.

Under no circumstances should you perform a trailer alignment by measuring off of the brake shoe, the brake pin, or the rim of a trailer. I know plenty of senior mechanics who have done it this way for 20 years. They have done it wrong for 20 years. Do not allow this in your shop. It is a waste of resources. It will not properly align your semi-trailer. What we want is to decrease the rolling resistance of the trailer by perfectly aligning the trailer for greater fuel economy and less tire wear.

Old School Kingpin Adapters

kingpin pogo stick

If you use a traditional pogo stick style kingpin extension tool, make sure it is equipped with a bulls eye level. If it is not, you will need a level to make sure the part of the kingpin extension tool that you attach your tape measure to is directly under the kingpin. This will only be accurate if you follow the first rule of any semi-trailer alignment procedure: make sure the trailer is parked on a flat level surface and the kingpin is at ride height. When you level out the trailer on a flat level surface, you are making the trailer and parking surface parallel with each other. Pogo stick kingpin extensions use a bulls-eye level to place the connection point under the kingpin. There's only one problem. Using a level doesn't guarantee the connection point will be under the kingpin. Using a bulls-eye level places the pogo stick perpendicular to the earth. There is no reference to the trailer.

Another problem you will routinely run into is pulling the pogo stick off from under the kingpin. It's not a big deal, it just happens. Parts wear out and you are trying to put the correct amount of tension on the tape measure to get an accurate measurement. Just reinstall the pogo stick and take another measurement. Eventually, I grew tired of the restrictions of conventional alignment tools and replacing them all of the time. What did I do? I created my own.

A Breakthrough in Kingpin Extension Design

I tried to look at every area of concern I had about existing trailer alignment tools. They fall off. They can't be used on a reefer or with a tire carrier. They wear out quickly. If you drop them, they bend or break. I know, in your shop nothing ever gets dropped and nothing ever gets set on top of anything else. Well in my shop it happened all too often.

I wanted a kingpin extension tool that was easy to install. It had to align itself perpendicular to the trailer, not the earth. And I didn't want to have to buy a new one every time someone sneezed on it.

Here it is. A heavy duty, laser cut, easy on/easy off trailer alignment tool that self aligns perpendicular to the trailer directly under the kingpin in a way that you cannot pull it off while taking a measurement. As long as you can guess which end of the trailer the wheels are mounted on, you can't put this thing on wrong. This kingpin extension is by far the best trailer alignment tool on the market. It drops down far enough that you can use it with a reefer tank installed, a tire carrier, or both. It can even be used if you have a side door lift gate installed. This kingpin extension can be used on any trailer application.


2 bazooka tube axle extensions 4 bazooka tube axle extensions trailer alignment tool set new kingpin alignment tool


Measuring Devices

A 50 foot steel tape measure with 32nd increments and a shorter tape measure for measuring the scrub angle (between the rear axles). I happen to have a 12' tape measure so that is what I use. A great measuring device for measuring the scrub angle on your trailer is a trammel arm. The trammel is used to measure the scrub angle on the curbside of the trailer first. The curbside is measured first because the curbside is usually the non-adjustable side of the trailer suspension. Lock the trammel arm in position. Hold the trammel arm up to the centers of the roadside axle tubes. If the centers line up, the scrub angle is perfect.

You will also need a tape measure tensioning devise. A fish scale will work.

Miscellaneous Trailer Alignment Tools

Other trailer alignment tools include a piece of chalk. I recommend that you use the chalk to write on the cement in front of each axle. Too many times mechanics forget the measurements. They usually write it down on a scrap piece of paper. It just doesn't work out for them. They run out of space, or after 3 attempts to align the trailer, they just get confused which measurement went where. It happens to me too. That is why I write each measurement on the ground in front of the axle I am measuring. This way I can line out measurements after I adjust axles with the new measurements. It sounds goofy, but it works every time.

If you use axle tube extensions like I suggest, you will need new hub cap gaskets for each axle end. If your trailer is on hub oil, you will need new oil for each end. If your trailer is on grease, you can usually just add what ever grease you had to remove to get access to the axle tubes. Be sure to add the correct grease for your trailer.

Other miscellaneous tools for a trailer alignment may include:

  • brake cleaner for cleaning parts
  • emery cloth or a gasket scraper to remove the old hub cap gasket
  • hub cap oil catch pan
  • new hub cap gaskets for each axle end
  • either 80-90wt oil or grease for each wheel end
  • miscellaneous tools for adjusting your particular suspension
    • a torque wrench
    • often one or more combination wrenches and sockets
    • sometimes it will require a special torx socket

Now that you know all of the proper trailer alignment tools. You are now ready for the next step in the trailer alignment. Prep for the trailer alignment.


We currently only stock bazooka style alignment tubes for tappered spindle axles. We do manufacturer tubes for pro-par stlye axle spindles. Please use the contact me form below for more information about any of our trailer alignment tools.

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