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12 Bolt Rearend - Project Road Rage, V.2

Our Camaro Road Racer Is One Step Closer To Hitting The Track With Our 12-Bolt Rearend From Moser Engineering.

Thomas J. Lyman Aug 8, 2007

In this installment of the newest addition to the Super Chevy fleet of project cars, we show a Moser rearend going in-actually from the Moser manufacturing facility in Portland, Indiana, to the Norco High School kids throwing it up into the bowels of the race car in California.

In the NASA Camaro-Mustang Challenge rulebook, 2007 is the first year anything other than the stock rear housing is allowed, and we figured that in order to have the best chance at even a top-10 finish, we should have the best equipment money can buy for a rearend. For this aspect of the project, we called upon the folks at Moser Engineering. The company's Complete 12-Bolt package was the first recommendation the technical department gave us, and we added to that a set of 3.42 gears, a TruTrac limited slip differential, and an aluminum performance differential cover. These components were chosen for the road racing application we're currently working on, but Moser offers all sorts of other options for rearends-from serious street applications to full-bore drag racing setups. As you can see in the following photos, there's a lot that goes into a complete Moser product, and installation is a fairly straightforward process.

Stay tuned for more on the buildup of the Camaro, and how the Moser 12-Bolt performs on the road course.

Sucp_0707_01_z 12_bolt_engine Bolt 2/23

The Moser Engineering Chevy 12-Bolt Housing unit is a newly designed casting, tailored towards those Chevy owners who want a virtually indestructible replacement rearend. The center section casting is made of nodular iron and the overall section is much stronger than the stock predecessor. At 11/44-inch in thickness, the tubes utilized are 11/48-inch thicker than a stock 12-bolt and have a 3-inch outside diameter. Thicker tubes greatly reduce the opportunity for a bent housing caused by twisting. The housing ends shown are Chevy-style, designed by Moser Engineering, and are CNC-machined forged. The mounts are multi-leaf perches for this particular application, but mono-leaf perches are available as well. Each housing unit is custom made to individual customer specifications. The length of the housing and offset of the perches or the housing itself can be adjusted to fit any application.

Sucp_0707_02_z 12_bolt_engine Tubes 3/23

Press the tubes into the nodular center section and install the breather hole. If you notice, the tubes are welded the entire circumference as opposed to OEM style 10- and 12-bolt housings that use four spot welds.

Sucp_0707_04_z 12_bolt_engine Housing_ends 4/23

The housing ends are then machined or "turned" down to fit inside the housing tubes for added strength. If you notice, the end on the left has already been machined.

Sucp_0707_03_z 12_bolt_engine Breather_hole 5/23

Tapping the breather hole. The hole is added to alleviate pressure from inside the housing, which will eliminate the possibility of blow-by, or blowing out the seals, which causes leaking of the rearend lube. One suggestion to help prevent axle-bearing breakdown is to use a Timken tapered bearing, as opposed to the standard ball bearing setup. The tapered bearing is manufactured to handle greater side loads for both racing and street applications.

Sucp_0707_05_z 12_bolt_engine Fabricated_housing 6/23

The housing is fabricated to customer specification and is now ready for the setup technician to complete the build.

Sucp_0707_06_z 12_bolt_engine Marking_caps 7/23

Chad Franks starts the setup process by marking the caps to ensure they remain with the appropriate CNC-machined side of the housing. Following the caps being marked, Chad thoroughly cleans the tubes, center section, and main cap holes. It's imperative that the housing unit is free of dirt and debris to assure a successful 12-bolt housing setup.

Sucp_0707_07_z 12_bolt_engine Pinion_gear_components 8/23

Components for the pinion gear installation include the pinion gear (3 series shown), 1310 yoke, crush sleeve, Timken tapered pinion bearings, oil seal, shims (amounts may vary based on desired setup), and lock down washers and nut.

Sucp_0707_11_z 12_bolt_engine Yokes 9/23

Two different style yokes are available for the 12-bolt housing application. The yoke on the left is a 1350 series yoke designed primarily for racing applications, while the yoke on the right is a 1310 series utilized primarily for stock GM OEM rears.

Sucp_0707_10_z 12_bolt_engine Install_bearings 10/23

Once the pinion is installed, installation of the carrier bearings follows. The posi unit shown is an Eaton 30-spline TruTrac unit. The carrier bearings must be pressed on completely.

Sucp_0707_08_z 12_bolt_engine Ring_gear 11/23

To speed up the process and make the securing of the ring gear to the carrier easier, Chad has preheated the ring gear to 300 degrees Fahrenheit and is bolting the gear in place.

Sucp_0707_09_z 12_bolt_engine Exciter_ring 12/23

Moser Engineering manufactures the only ABS compatible aftermarket 12-bolt rearend. Shown is the Moser Engineering designed exciter ring, otherwise known as a reluctor ring, and an Eaton posi unit.

Sucp_0707_15_z 12_bolt_engine Shims_in_place 13/23

With the shims in place, bearings pressed on, ring gear bolted down, and the pinion gear set, the limited slip is placed inside the center section of the housing unit by way of a case spreader.

Sucp_0707_12_z 12_bolt_engine Carrier_installation 14/23

Following the installation of the carrier and the mounting of the main caps, Chad applies a marking compound to check the gear pattern.

Sucp_0707_13_z 12_bolt_engine Optimal_gear_pattern 15/23

This picture shows the optimal gear pattern. The pinion depth and pattern are set depending on the gear manufacturer's recommendation on each particular set of gears.

Sucp_0707_16_z 12_bolt_engine Pattern_set 16/23

Once the pattern is set, the gear backlash is set. Backlash is the amount of space between the gears. For the Moser Engineering 12-bolt units, the optimal backlash setting is dependent on each customer's specific application. The particular application shown asks for a backlash of .008.

Sucp_0707_14_z 12_bolt_engine Gasket 17/23

A gasket is placed on the housing to prevent rearend fluid leakage and the Moser Engineering aluminum performance cover is set. The cover bolts are torqued to 25 ft-lb.

Sucp_0707_19_z 12_bolt_engine 12_bolt_housing 18/23

Another option for the 12-bolt housing units is the choice of rearend covers. The chrome cover is the standard choice (shown on the right), and customers have the choice to upgrade to a stronger Moser Engineering aluminum performance cover.

Sucp_0707_17_z 12_bolt_engine Check_package 19/23

Upon arrival, the Norco High School students checked the 12-bolt package to make sure all the pieces arrived safely.

Sucp_0707_18_z 12_bolt_engine Students 20/23

Here, some students of the Automotive Technology program at Norco show how light the 12-bolt appears to be. From left to right: Chris Agamaite, Jason VanLoon, John Dimond, Jeremy Weaver, Zac Cloar, Dillon Maddox, Zeb Francoeur.

Sucp_0707_21_z 12_bolt_engine Assemble_suspension 21/23

The students assembled the suspension pieces to the 12-bolt outside of the car before attempting an install. The BMR Panhard bar has already been attached to the mounting point that Moser supplied with the stock-type rearend. This housing will work with any third-gen application.

Sucp_0707_22_z 12_bolt_engine Place_bolts 22/23

Here, the students place the 12-bolt into the car. As you can see, (especially with the project nature of our F-body) installation was a snap. Notice that the BMR lower control arms have already been attached, as well as the Bilstein struts. Now we're waiting on the springs from Eibach and about 10,000 other parts before we go racing.

Sucp_0707_23_z 12_bolt_engine Completed 23/23

The Moser 12-Bolt is now officially part of Project Road Rage. Watch out in coming issues as we put the finishing touches on the suspension (with pieces from BMR, Bilstein, and Eibach), get ready to wire the car up, and fabricate a road racing-specific rollcage-complete with NASCAR-style door bars.



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