Measuring Up Moser Engineering’s New Pro Flange Race Axles


Making rugged rear end components has been Moser Engineering‘s claim to fame since 1982, as they’ve established themselves as one of the go-to sources for affordable American-made axles and driveline components.  Like any good manufacturing company, Moser and its products have advanced alongside the ever-evolving demands of the most hardcore of racers, and the introduction of their new Pro Flange Axle is the culmination of the hours that their engineers have dedicated to designing the lightest and strongest flanged axle possible.


Moser’s Extreme Pro Axle is designed to be a direct replacement for any current 9-inch axle setup. The entire kit comes decked out with new axle studs and every component to swap in these improved components.

The newest flanged axle to surface from Moser is the first redesign of a lightened flange in about 20 years, as Moser went back to the drawing board to rework these extreme duty axles. This newest model has gone through a considerable number of revisions during its test phases. During this rigorous testing, the engineers discovered that their current floater hub design was the ideal setup for a lightened flanged axle, and as such, the new lightweight Pro Flange is almost exclusively based off their current full floater style assembly.


While Moser has never witnessed an instance where the previous Star Flange has failed, they chose to remain ahead of the game in terms of safety and longevity with the new design. For that reason, we opted to go with the updated Pro Flange on our Dragzine project car, BlownZ.

“We started with the floater-style design to get a good baseline reading, and with a few minor tweaks, the core shape of Pro Flange design arose,” said Jeff Anderson of Moser Engineering “At the end of testing, our engineering department was pleasantly surprised by the strength and lightweight benefits of this updated flange.”


The Moser Extreme is a 40-spline, gun-drilled and lightened flanged axle manufactured with premium quality USA-alloy steel, forged from Moser Engineering designed tooling, induction heat-treated to optimize torsional strength, and is 100 percent magna-fluxed.

As power levels have increased we’ve begun to see issues, especially in during times of extream tire shake, the potential of axle failure is increased.” -Jeff Anderson, Moser Enginering

The whole purpose of this redesign is to minimize rotational mass and retain rigidity in the most demanding of conditions. It’s well known that less reciprocating mass results in less power loss throughout the drivetrain. This new setup is the optimal balance of a lightweight design and race proven strength. While lightening the axle has been the center of attention over past years, with gun-drilling becoming a major contributor to weight reduction, the axle flange has not received much attention until now. Quicker and faster 1/8- and 1/4-mile passes have pushed the entire drag racing community to redesign a massive amount of products to remain ahead of the curve.

The install was pretty straight forward on these axles. The axles feature a shaft size of 1.705-inches with oversized 1.774-inches bearing seats that make this upgrade a breeze on this application.

“As power levels have increased, we’ve begun to see issues, especially during times of extreme tire shake, that the potential of axle failure is increased,” Anderson explains. “The limitations of the previous designs have come to light as power levels have increased. We’ve seen some failures — not necessarily with our product — that made us go back to the drawing board to address any potential weakness of the current lightened flange design.”


The installation of the studs was simple after utilizing the supplied wheel lugs as jam nuts, after they received a bit of loc-tite.

The Extreme Pro Flange axle was constructed to aid the racer who’s looking to pull every possible pound of weight out of their land-locked missiles. The additional advantage of weight reduction could very well be the difference between winning and losing any race … after all, we’ve all come across a moment in time where we need just a bit more to edge out the guy in the other lane.

IMG_4336While these axles do not carry a power limit or torque rating, as the effectiveness of this design is based upon a number of different factors; with some being vehicle weight, rear end gearing, and tire design. As such, Moser recommends that you discuss this conversion with one of their technical representatives to ensure you get the right axle setup for your application. Be sure to check out Moser Engineering to outfit your 1/4-mile ground pounder with the latest and greatest rear end components.

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About the author

Justen Spencer

Justen is a Ford modular motor fanatic with seven years of professional drag racing experience, and multiple championship seasons in NMCA West and PSCA. Originally from Las Vegas, he is the proud owner of four Mustangs, one that sees regular track time. When not racing, Justen can be found in the garage maintaining his championship-winning car.
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