Moser Engineering’s Circle Track Rear End Package

In our quest to make an indestructible dirt track race car, we began by changing out the drivetrain piece by piece and replacing the worn out components with some budget minded but top shelf equipment. When it came time to upgrade our street stock project car’s rear end, there was only one real choice – a bulletproof Ford 9 inch rear end.

For a bomber stock, it’s the only way to go. Most of the dirt tracks that allow a Ford 9 inch rear end also allow a floater rear end for safety. With a variety of companies that manufacture the Ford 9 inch, we knew there were a lot of alternatives available. However, we selected the Circle Track Package from Moser Engineering as our weapon of choice.

The Madd Maxx Street Stock project car was overdue for the rear end swap, and it was quite obvious when we put the car on our two post lift, raised it a couple of feet off the ground, and put the car in gear. The back right tire wobbled and shook so badly that we wondered how the driver managed to keep all the fillings in his teeth. Further investigation turned up a bent axle and rear end housing.

It was clear that Maxx had made contact with another car or the wall sometime in its past. We talked with Jeff Anderson and Shane St. Myers at Moser Engineering to determine the best options for our car and type of racing. There were several different options available in the Moser line of Ford 9 inch kits, and we wanted to outfit our car with the kit that offered the best chance to get around the track the quickest.

The rear end housing comes with a couple of snout options. We opted for a Grand National Style Snout.

Moser’s CT Rear End Housing
Moser Engineering has a Ford 9 inch housing for every type of racing application imaginable from hot street and drag racing to circle track racing. Selecting the Circle Track housing was an easy choice since it was the only option as far as we were concerned. Starting with a superhero strong housing made of all new material (not just a refurbished housing pulled from a wrecking yard), Moser constructs their CT housing specifically for the oval tracks.

According to Jeff Anderson of Moser, “The CT housing incorporates fish mouth cuts at the ends of the banjo housing for added strength where the 3 inch DOM axle tubes join, as well as bracketry made with newer, stronger materials than the original Ford housings. This all adds up to a housing with superior strength compared with many other housings being run on the ovals.” The housing also comes standard with an oversized fill plug, standard sized flush mount drain, and a vent tube incorporated in the housing. The only decision we needed to make with the housing was whether to go for the Grand National Performance snouts or the Moser Dual BP snouts at the tube ends. We opted for the Moser snouts.

Assembling our Moser DB hub with Wilwood rotor.

CT Hub Package
Moser offers a hub package which contains everything you need to assemble the brake rotors and hubs to the housing. There are three different basic hub packages offered by Moser. There is a 5 lug, 5 inch pattern (5X5) for the Grand National Style Hubs, and for the Dual Bolt Pattern Moser snouts there is either a 5 X 4 3/4 inch or a 5 X 4 1/2 inch pattern.

All three styles of hubs are made from 4140P aircraft quality alloy steel. The 4140P Moser Hubs are IMCA approved for use in IMCA series racing. Moser’s Jeff Anderson explained that the “hubs made with 4140P steel are 35% stronger and lighter than hubs made from 4130 steel.” In addition to the hubs, also included in the hub package are bearings, seals, steel drive plates, and steel brake rotors. The CT drive flanges are also made of the 4130P steel and are available for three different hubs offered by Moser. An optional aluminum drive flange is available for the Grand National Style Hub.

We Let the Experts Guide Us
Shane St. Myers offered to help us make the best choice for our application, and we took him up on the offer. While we felt pretty special about getting the expert advice, Shane explained that Moser has a technical crew assigned to help anyone that calls their tech line. In short, we were getting the same assistance that is available to everyone, yet that didn’t dampen the feeling of great customer service that we got from Moser Engineering.

A complete package that includes all bearings and hardware.

Shane has worked with some of the best dirt racing teams from all over the country and has spent a lot of time at tracks like Eldora. Based on his experience along with the information that he pulled out of us with some pretty shrewd questioning, he advised us to go with a fairly common Moser CT Package.

Shane explained, “When it’s legal in the rules to use a floater rear end, you should. A rear end with floating axles is a much safer bet on a dirt track where a car is much more likely to have a rear tire hit the wall or another car.” Likewise, a larger diameter axle is less likely to get damaged when there is a lot of torque to the ground or a lot of paint swapping going on during the racing. Based on Shane’s recommendation, we selected a floater rear end with 31 spline axles, aluminum floater hubs, and Wilwood rotors. Changing from drum brakes to rotors was another safety feature that we really wanted to take advantage of. The last thing we needed to do was select the mount options. Because the rules state that the rear end mounts and suspension needed to be OEM for the type of chassis being used, we ordered the stock leaf spring mounts for a late 70’s Camaro.

Installing the third member gear case into the Moser housing.

Additional Items Included in Moser’s CT Rear End Packages:

  • Inner and outer bearings and races
  • Hub seal
  • Axle seal
  • Dust cap O-ring
  • Drive flange hardware
  • Adapter hardware
  • Dust cap hardware

Our Moser CT Rear End Installed in Project Car Madd Maxx.

Last Word
Moser Engineering’s CT Rear End Packages help take the headache out of buying a new rear end for your race car. Everything you need, with several different options and the assistance to ensure that you get the right part the first time, is available by calling Moser’s tech line. Our rear end took an afternoon to install from start to finish, and it gave us the performance that we expected when we ordered the package. The added bonus was that the rear end package was a true “bolt in” replacement. There was no struggle with ill-fitting parts, no running around for additional parts that were not included in the package, and no settling for less than what was advertised. The Moser CT Package is a complete kit that delivers on its promise to be a high performance upgrade without any hassles.

The Specs on Our Rear End:

  • #A4131 Moser CT Axles – 31 Spline Solid
  • 60″ Moser CT Leaf Spring Housing with Centered Pinion
  • #43003C DBP Hub w/ Races & 3” Coarse
  • #4305 DBP Steel Drive Flange
  • #160-0471 Wilwood Rotor
  • #CE-5011 Currie 31 Spline Full Spool
  • #CE-4026 Currie Cast Iron Gear Case
  • 6.50 Gears


Installing the 31 spline axle with a 3/8" bolt spacer on the driver's side.


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About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
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