For most automotive enthusiasts, there are some jobs we love to do in our own garage and others that we have no choice but to call on the professionals. Everyone has a different skill level so it’s hard to tell someone whether they possess the skills to perform a particular task or not. The common rule is: if you’ve never done it before, ask someone who has experience to help you.

That’s exactly what Moser Engineering does with its online forms when ordering a custom axle housing and a set of custom axles. They have done it thousands of times before, and they’re available to help you with the process. The forms for measuring a custom housing can be downloaded, and the instructions help you take all of the necessary measurements step by step. If you get stuck, or if something is unclear, the tech support staff at Moser is just a phone call away.

This is not to imply that measuring a rearend is a simple task, as it does require a strong attention to detail, but it’s no longer reserved for those who have an advanced skill level and thorough understanding of how to measure the components. In the latest videos from Moser Engineering, they not only demonstrate how to measure the housing, but also provide key information on the proper way to identify it.

Most gearheads know exactly what they have in their car, but unless that car was bought brand new and kept by one owner the entire time, there’s no telling who may have swapped out the rearend from another vehicle as an upgrade or replacement. As Moser explains, sometimes the design and measurements can change from year to year and the one in your car may not be the original rearend – even though it could look stock and fit in the factory mounting location. Because getting these dimensions correct is critical, it will require following along with the guide on the downloaded form.

Measuring For A New Rearend

After downloading the form, the tools needed for measuring the housing are very basic but are required to get the exact measurements. Therefore, Moser recommends the following tools:

• Tape measure
• Two straight edges
• Dial calipers

Even if you’re absolutely sure what rearend is in your car, Moser also recommends that you go through this process anyway to be sure. Don’t rely on measurements found online, as it would be difficult to tell which rearend was used for those measurements. We also recommend that you don’t assume all rearends are the same, and for that reason the measuring is a must.

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Don't guess at the flange type, warns Moser. Always take the measurements and match them up. If you get stuck or you're not sure, technical assistance is just a phone call away.

The forms have most all of the popular applications, such as a Ford 9-inch, Dana 60, GM 12-bolt, etc., and Moser will assist anyone who is not sure which they have by providing key points that will help identify the housing. Once the housing type has been established, Moser’s forms provide the necessary information and measurements to match up the flanges and provides the space to list the measurements for both sides of the housing.

Moser provides several of the most popular and widely used axle flange dimensions and shows the proper way to measure and identify the flange. Moser warns us not to base our identification on just a visual of the housing flange.

A few of the flanges may look similar, and to be absolutely sure which flange you have Moser shows how to measure between two bolt holes to get the proper distance so you can match it up to one of the drawings referenced on the form. If your measurements don’t match any of the existing dimensions, Moser recommends you call a one of their service representatives to discuss what you have.

If the axle housing is completely out of the car, with the differential and axles removed, it does make it easier to take all measurements. With the axles removed, it’s also easier to measure the bearing seat to match that up to the order form, as well as measuring flange to flange.

For an assembled axle, Moser’s video shows how to take measurements based on the axle flange where the wheel mounts, which is done with the brake drums or rotors removed to get the actual measurement.

For some of the tasks, like measuring from axle flange to axle flange, enlisting the help of a friend will really come in handy because every dimension provided to Moser needs to be accurate. With the differential/center section removed from the housing, one tool that can greatly help with measuring is the pinion centering tool. This tool allows you to measure the pinion offset on many popular differentials and is designed to fit the flange on both drop out or rear cover style differentials. This measurement will be based on the center line to the housing end, minus any axle or brake components.

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Measuring the housing in or out of the car can be done, but for accurate results the axles should be pulled from the housing.

For installed third members, measuring from housing end to the center of the pinion nut will provide the same measurement, but keep in mind that this is not the same as the axle length. This measurement is for the pinion offset only.

Four-link and ladder bar suspensions are also included in the measurement forms. Moser discusses how to take those measurements and insert them on the form.

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Measuring to the pinion nut center will also give a reading for the housing end to the pinion center; make sure to measure both sides.

Measuring Rear Axle Length

One of the reasons for ordering a custom axle housing could be that you’ve installed mini tubs and moved your leaf springs in. This will allow you to install a wider tire and wheel package, but it also enables changing the offset of your wheels. Once the springs have moved in, however, the spring perches will have to be ordered based on the new width – and Moser Engineering can help with that as well.

For those ordering a modified axle housing and needing new axles, Moser can match up the proper axle length based on the new dimensions, but they will also need to know details about the axles. The process for measuring axles is similar, and it requires similar tools.

Moser recommends the following tools:

• Tape measure
• Two straight edges
• Marker
• Dial calipers

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To measure the axle, there are a few dimensions necessary. Don't assume that the right and left axles are the same length.

The process for filling out the form for new axle shafts, whether they are replacement or modified, Moser will still need to know the axle housing type. The ends will need to be measured and identified just like the housing. For the reasons explained with measuring the housing, Moser recommends taking measurements and not relying on the visual alone.

Because not all axles are the same length for driver and passenger sides, Moser instructs to take measurements for both axles, rather than assume they are identical. With the axle removed, which is the only true way to measure it, measuring from the inside end to the bearing seat, the outer flange, and from the outside flange to the bearing stop.

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Measuring the hub and flange diameter are just as important to make sure they'll fit inside a brake rotor or drum. After the measuring is done, Moser can get to work building your new axles.

Another important set of measurements that cannot be avoided includes the axle flange diameter and the axle hub diameter. These measurements are crucial to ensure that your new axles will fit inside brake rotors, drums, and wheel center hubs.

Be sure to check out both videos for full instructions and contact Moser Engineering technical support if you have any further questions. The forms can be found on Moser’s website along with all of its products ranging from stock replacement to completely custom rearends for nearly any vehicle.