How You Can Save Money On Housing & Axle Narrowing With Moser

Moser Engineering is renowned for its custom, aftermarket rearend housing offerings, including the Muscle Pak series and the fabricated M9, M88, and others. While a worthy investment if you have the coin, the Moser team knows not every racer has the discretionary income or the desire for higher-end, custom housings for their car…particularly those new to the sport who are operating on a budget or simply don’t yet know what they want long-term.

A customer’s fresh (well, it was a fresh at one time, anyway) Ford 9-inch housing, at factory length.

Recognizing this grassroots beginner’s segment of the marketplace, Moser offers a service for narrowing a customer’s housing — be it OEM-stock or previously modified — to their specifications to allow for larger tires and higher spline-count axles, all in the name of saving the racer money. And while sure, you could narrow your own housing at home, Moser’s team has a wealth of experience to ensure the job is done right if you’re not confident in your own abilities.

“This is a service that’s really directed at guys in the sportsman ranks and on the beginner edge, that might have a classic Camaro or Mustang and they have enough power that they can’t get the car to hook and need a little more tire, but they’re trying to do it on a lower budget,” says Moser’s Jeff Anderson. “Maybe they’ve got a 12-bolt, an 8.8, or even a 9-inch in the car and they’re switching it over to a larger spline count, or they want to narrow it to put some bigger tires under the car, and they can’t afford to have a custom Muscle Pak built.”

You can measure the housing ends -- and your pinion offset -- by checking the length from the center of the pinion to the housing ends in each direction. Double-check your work by measuring end-to-end to ensure the calculations match before shipping your housing off for narrowing.

“They look at ways to save money, and one of the first things you’ll find guys do in a door car type of setup is narrow a factory or a used rearend just to save money and see where they go with the project. Sometimes, in the beginning, you’re trying to make things work, or you decide to go a different direction, and this way you can save some money, just focus on narrowing your axles or buying new axles to size, and sort your program out,” Anderson explains.

For Moser, this service helps bring people into the industry and the sport of drag racing, and is also a goodwill gesture that it hopes will bring customers back when their love of the sport grows and they’re ready to step into a custom housing and axle package. 

A Moser tech measuring his cut and removing the requested length of axle tube.

“We still remember the grassroots, when we started out decades ago, and how important it was to save money and this is something we’ll continue to offer forever…I don’t see us not offering it, because it’s a way of helping racers,” Anderson says. “Not a lot of companies at this level offer a service like this anymore.”

Moser provides an order form that spells out the specifics it needs to ensure the housing returns to you exactly as you envisioned it, requiring only some basic measurements to be obtained. There is also a range of possibilities to meet your suspension requirements, as well, to get you a turnkey housing to bolt under your car.

New housing ends, ready for prep and installation.

“We know some people aren’t confident in the measuring or the measurements they need to supply. There’s more than one way to skin a cat when it comes to getting those measurements. The easiest for a lot of guys, if you’re going to narrow the housing and you know what size tire you want on the back of it, is to go ahead and remove the rearend, put the tires and wheels under the car, and measure back-of-wheel to back-of-wheel, and give us that dimension. That will tell us where the housing needs to be, and we can figure backwards from that with a few more bits of information.”

That extra information includes the style of brakes the customer intends to use (be it Moser drag brakes, Wilwood or Baer discs, a more economical weld-on bracket-type, etc.) and the desired style of housing end. Axle hangout is one variable you’ll need to clarify ahead of time — this is measured from the outside of the axle flange to the outside of the housing end, without the backing plate installed. Hangout is a critical measurement in housings and axles, as it determines the spacing where the brake rotor rests between the caliper and pads — miss that calculation and binding can result.

“We can work with all of the customers’ requirements, and we can give guidance from our end with a simple phone call before they send the housing in. But it’s not rocket science…it’s very straightforward,” Anderson says.

As long as you haven’t already narrowed the housing to the point that too little tube exists on one end or the other, Moser can modify your pinion offset to match the vehicle.

“Depending on the housing someone has purchased, the pinion offset may not be a direct, or good match for the application — sometimes we can play with that pinion offset and move it if necessary. If the housing came out of the vehicle, then of course we’d just remove the same amount of material from both sides to maintain the factory pinion offset. Generally, though, if there’s enough tubing length, we can change the pinion offset, and it doesn’t cost any additional money.”

Once the axle tube is cut to length, Moser uses a fixture to center the new housing end for true, will tack weld it on, check again, and then final weld.

If you don’t have a pinion gauge tool in your arsenal or at your disposal, you’ll measure the old-fashioned way to the center of the pinion hole or pinion nut from the left and right housing ends (what Moser refers to as the F&G measurement). As a key check of your work, these numbers should total up to the entire length of your housing — if they don’t, your measurement is off on one side or the other. Once your numbers check out, keep track of the value for the driver’s and passenger side, and Moser can utilize those to build-in your pinion angle when narrowing the housing.

Moser’s order form, spelling out housing, housing end, axle, and hangout calculations.

When Moser receives a housing, it will place alignment bars through it to ensure it’s straight and true, and can usually correct light bends in a tube — it’s been known to notch a tube and press it, and in rare cases, even re-tube a housing.  To provide a drop-in housing out of the box, Moser can install your desired suspension tabs and brackets in the proper location — Moser sells spring perches and four-link brackets, and can also work with your own supplied four-link brackets, or those from distribution partners.

Checking pinion offset. So long as you have enough axle tube on the shorter side, Moser can move your pinion offset to fit a non-OEM-intended vehicle.

As an added service, Moser can cut and even re-spline your existing factory axles, providing a bit of an upgrade and saving one from determining their own axle hangout measurement. Anderson notes that an axle can be cut to the proper length and, if the housing is being narrowed enough to eliminate the original splines, it can be splined with a higher tooth count. This generally requires about 2.5- to 3-inches of the axle to be removed to get past the old spline (the new area of spline will need to be at least the same diameter as what was removed since you can’t add material if it’s undersized). Measurement instructions are also provided on the order form for these additions, as well.

Moser takes great pride in its two-day turnaround for custom housing and housing modifications, and in general, as long as the prudent information is supplied and accurate, the Moser team can get your housing completed and on its way back inside that timeframe.

“We have a lot of packages coming in here every day, so most critical to meet the two-day turn around is to have all of the information inside the box — your name and return address, phone number, so we can contact you with any questions,” Anderson explains. “And then, if we’re narrowing the housing, we need the basic dimensions, how much you need removed, total housing width or how much you need removed per side, whether you want the pinion offset changed, what you’d like as far as housing ends go, and then, whether you want us to look at cutting and re-splining your axles. And then, just make sure the housing is bare and clean — UPS and FedEx typically won’t ship anything that’s leaking fluids. You don’t need to ship us the internals unless we’re setting it up for you. Just be sure it’s wrapped up good, because shippers have been known to drop housings and bend the tube and the ends.”

Whether you’re a newcomer to drag racing, you’re racing on a strict budget, or you simply trust the experts rather than veering down the DIY road, Moser Engineering can you get you right in the game, transforming your factory housing and even your axles into suitable racing pieces at a fraction of the cost of new.

Instructional Videos From Moser On Measuring Rearend Housings, Axles, and Axle Hangout

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About the author

Andrew Wolf

Andrew has been involved in motorsports from a very young age. Over the years, he has photographed several major auto racing events, sports, news journalism, portraiture, and everything in between. After working with the Power Automedia staff for some time on a freelance basis, Andrew joined the team in 2010.
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