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Moser 9-inch Rear Axle Housing - Project Hardtop Hellion

Moser & Competition Engineering Under the Hardtop

Jake Amatisto Dec 4, 2013
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Even we diehard Chevy fans can't ignore the brute strength of the Ford 9-inch rear axle assembly. As a staple in the off-road and drag racing community, this beefy design is a solution to spindly stock rearend breakage, and its removable center section makes trying out different gear ratios super-easy. Although purists may cringe at the thought, hardcore Chevy drag racers have accepted this design and, these days, most fast Chevys have this part under their car without apologies.

When it comes to high-performance rearends, Moser Engineering is among the top manufacturers in the industry, and we recently perused their user-friendly website and were impressed how they setup a multiple choice format that made ordering a rearend a breeze. Whether you're looking for a fabricated housing to handle brutal horsepower or something more of a stock replacement, Moser has what you're looking for. And, for those that are impatient enough to order car parts in the middle of the night, Moser's site caters to the internet savvy that would rather select exactly what they want and know that their order is in process, regardless of the time of day. Want a narrowed 12-bolt for your second-gen Camaro? Or how about something weird like an 8 3/4 Mopar housing for your leaf sprung Chevy, Moser can do that too, they are that capable. You just need to know some things like: desired gear ratio, differential type, bearing end style, overall length, axle spline count and spring perch/suspension type.


Quick Specs:

  • New 9-inch Moser housing
  • 35-spline axles
  • Nodular center section
  • Wavetrac differential
  • 3.75:1 gears
  • There are two basic complete rearends you can order from Moser; the built-to-order line, which you can custom tailor your ideal rearend, and the MusclePak line of rearends, which are ready-to-go, brake-to-brake. Both options can be shipped to your door within two business days after you complete the online order. The hasty shipping is cool; it definitely beats digging a housing out of the junkyard then having it rebuilt and welded up.

    For our Chevy II project, the Hardtop Hellion, we opted for Moser Engineering's built-to-order, bolt-in 9-inch housing, which they offer sized and ready-to-go for these little cars. We weren't even going to begin to try building the 8.2 10-bolt rear that came in our well-worn 1963 Nova, nor were we going to pull a greasy rear from the junkyard; Moser makes the decision easy. With a few clicks we had a new heavy-duty 9-inch on the way. Features include an American-made housing with OEM located mounting provisions, seamless steel tubing (3-inch O.D., ¼-inch wall), we upgraded to custom alloy 35-spline axles, bearings, 1/2-inch x 3-inch screw in wheel studs, seals, heavy-duty retainer plates, new housing ends (we ordered ours with large Ford-style ends), t-bolt kit, aluminum pinion support, nodular iron case, and a 1310 Series pinion yoke. For gears, we went with 3.75s, but there's long list of ratios available. We may be testing various sized tires and possibly and overdrive gear on this car, so being able to swap gears easily is a nice feature. And, instead of a typical posi unit, we upgraded to the WaveTrac differential (see sidebar on page three).


    Moser offers just about any differential you could want; from full spools, to lockers, to good 'ole posi-units. We actually went with a WaveTrac diff for our Nova project, which is a positive locking diff that engages smoother and quieter than other differential designs. The WaveTrac provides the best features of a locker, without any of the downsides...and unlike a locker, you can aggressively autocross with it, too.

    Wavetrac Differential Specs:

  • Handles up to 1,000 lb-ft of torque
  • Super strong worm gear design
  • Positive locking
  • Quiet operation
  • With the rearend out of the car, we cleaned the underside of the Nova, and to bolt up our Moser 9-inch, we used Competition Engineering's Slide-a-Link traction bars (PN2099) and Adjustable Drag Shocks (PN2720). The Slide-a-Links are an easily installed traction device for leaf spring cars that can drastically improve your car's traction by changing the instant center so that your car transfers weight more effectively.

    We have to point out the great job Ben Hermance did to capture what this project will look like. In the following month we plan on showcasing the next step in our Chevy II build, where we lose the greasy stock steering components for a much nicer column, wheel, and linkage.


    1. With some clicks of a mouse and a few days later, we had a Moser 9-inch ready to bolt under our ’63 Hardtop. Because we plan on doing some welding on this housing at some point, we opted to order the housing in bare metal, however, Moser offers them powder coated as well. We feel much better about grinding off spray paint rather than nice powerder coat.


    2. Moser offers axles in virtually any length, from 31- to 35-spline. We opted for axles with 35-splines since we plan on launching this car pretty hard at the dragstrip. For hardcore drag racing, Moser also offers gun-drilled 40-spline axles as well.


    3. Eastwood has been a great help on this project so far, supplying us with their Chassis Black paint, as well as the new 2K Aero-Spray Chassis Black paint, which is a two-part paint that is made to be super-tough and resilient to chipping. We used a can on the Moser housing before hoisting it into place.


    4. Removal of the stock rearend starts with the shocks. The top portion of the shock is bolted to a bracket, and the bracket gets fastened under the car with two bolts; the shock studs don’t extend into the trunk like we originally thought.


    5. The factory leaf springs are attached to the rearend using a locator pin/clamshell bushing design that envelopes the spring to keep the rearend in place.


    6. Once the shocks, shock brackets, and emergency brake cables were removed, we lowered the factory 10-bolt out from under the Nova.


    7. The center section we ordered from Moser Engineering is a Nodular iron piece that’s been equipped with 3.75:1 gears, an aluminum pinion support, and a Wavetrac differential.


    8. Removal of the stock leaf springs starts with the front eye bushings, then the rear shackles.


    9. A pry bar detaches the setup with ease.


    10. Once the back of the car was clear of factory components we took a wire wheel to the greasy and rusty underside before spraying it with Eastwood’s Chassis Black spray paint.


    11. Before installing the leaf springs back under the car, the Slide-a-Links from Competition Engineering called for aluminum bushings to be pressed into the front eye of the spring. To ensure they go in smoothly, we made sure to remove any residual rubber from the eyelet using a wire wheel on a high-speed drill. The aluminum provides no deflection and really solidifies the whole setup.


    12. This graphic shows how easily the Slide-a-Links are assembled. These will definitely help our Nova hook up by adjusting the instant center, helping weight transfer to the rear tires.


    13. With the aluminum bushings pressed into place, these zinc-plated brackets are bolted to the front eyes. This bracket holds the front portion of the Slide-a-Link bar.


    14. To re-install the leafs, we had to grind the factory eyelet bolt slightly in order to fit it through the bushing.


    15. We also had to make sure to lubricate the bushings with high-pressure grease.


    16. To assemble the links, first we installed the lower shock brackets that come with the traction bars, then using the appropriate heim joints, installed the bar itself into place. The solid heim goes in front, while the two-piece one bolts to the shock bracket under the axle.


    17. Since our Nova is destined for the drag strip, we ordered Competition Engineering’s drag shocks (PN2720) for the rear. These are affordable pieces that bolt in the stock location and can be switched from extra firm (XTF), firm (F), and soft (S) by a simple twist.


    18. Once the traction bars were bolted up, we moved onto the rear brakes. Classic Performance Products sent us their 11-inch front and rear disc brake kit that will allow for our 15-inch drag wheels (PN 6264FRBK-D) for the Moser 9-inch rearend.


    19. These brackets from CPP double as axle retainers, as well as caliper brackets.


    20. Various thickness spacers are used to properly position the calipers over the drilled and slotted rotors.


    21. We ordered our Moser axles with 3-inch long wheel studs to make sure we’ll be legal at the dragstrip, so open, acorn-style lug nuts were used to bolt on the Rocket Racing wheels/Nitto Neo Gen Tire combo. We also have to mention that we plan on lowering the Nova significantly once the engine, trans and interior are in place. Also, once the car is at race weight, we’ll be able adjust the pre-load of the Slide-a-Links using these nifty wrenches from Competition Engineering, which we highly recommend getting if you order the Slide-a-Links; the adjuster nuts on the bars are larger than 1-inch and not everyone’s tool boxes have large-sized open end wrenches on hand.


    Nitto Tire
    Cypress, CA 90630
    Classic Performance Products
    Placentia, CA 92870
    Competition Engineering
    Guilford, CT 06437
    Moser Engineering
    Portland, IN 47371
    Eastwood Company
    Pottstown, PA 19464
    Rocket Racing Wheels
    Chattanooga, TN 37406



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