Horsepower and torque represent the Holy Grail for car crafters. But the problem with more power is that when it’s matched with large sticky tires, it quickly uncovers the next weak link in your drivetrain. Stronger transmissions and large, nitrous-ready driveshafts merely transfer that power to the axles. When it comes to stock GM rear axles, the dreaded C-clip axles soon become worrisome. GM’s original idea to retain the axles with C-clips inside the differential was innovative, but a flaw in the design is that if the axle breaks, there is nothing to retain the axle inside the housing. When an axle (along with the tire and wheel) comes out of a car at speed, it usually tears up the body on the way out. It’s not pretty. Ford bearings used in most aftermarket axles are much larger than stock 10- and 12-bolt axle bearings. For this reason, the aftermarket created the simple C-clip eliminator kit to make them work. The c-clip eliminator kit required cutting off the outer end of the c-clip axle housing and replacing the stock bearing with a larger one inside a pair of aluminum pillow blocks. While several companies sell the c-clip eliminator kit, the problem is that they do not allow for the use of aftermarket disc-brake kits, and, in our experience, they leak. For these reasons, the c-clip eliminator kit is not a good idea for street cars. There is a better option, but it requires fabrication skills. We took our 12-bolt Camaro rear-end housing over to Tim Moore at Moore Automotive in Sun Valley, California, to run through this procedure for us. The better idea is to remove the entire stock 12-bolt housing-end and flange assembly and replace it with new, high-strength steel housing ends from Strange. The benefit, besides positive axle retention, is that companies like Strange Engineering offer GM-pattern housing ends that use the larger Ford 3.150-inch-diameter axle bearing. This larger bearing offers increased strength, which, when combined with a stronger axle, produces an extremely durable rear-axle package. This job demands that the new housing ends be precisely mounted to ensure that the housing is straight and does not induce either toe or camber into the axlehousing. Accomplishing this task demands the use of a mandrel. None of this is rocket science or even really difficult, as this type of modification has been going on for years. We found a mandrel tool from Mittler Brothers that makes this job even easier. The tool is not cheap at $550, but it includes a 60-inch-wide, 11⁄2-inch-diameter steel mandrel bar and several adapters that precisely establish the axle centerline using the differential bearing saddles. This tool also locates the housing ends. All you have to do is line up the ends and weld them in place. While this may not be a task that every car crafter should attempt, we thought it would be worthwhile to illustrate the process so at least you know what the job entails. If you farm this out to a fabricator, you can expect to pay $200 to $300 for the job. But if you see more than a couple of these conversions in your future, it might be worth the investment to buy the tool from Mittler Brothers and do it yourself. The only other tools you’ll need are a tape measure, a digital angle finder, a cut-off saw, and a 200-amp MIG welder. Here’s how it all went down. Parts List Description PN Source Price Strange axle package P3104 Summit Racing $396.00 Strange housing ends H-1143 Summit Racing 69.95 Mittler Bros. tool 1000-RENK1 Mittler Bros. 550.00 While cutting off a stock housing end and welding on new ones may seem intimidating, the job is actually not that difficult if you take your time and measure and cut carefully. While cutting off a stock housing end and welding on new ones may seem intimidating, the job is actually not that difficult if you take your time and measure and cut carefully. Here is the Mittler tool, with the 11⁄2-inch mandrel bar and the adapters. The kit comes with all the center supports for 9- and 8.8-inch Fords, 10- and 12-bolt GMs, ’57–’64 Olds, as well as Chrysler 83⁄4 and the Dana 60. The small adapters are the center supports that fit inside the main caps. The larger adapter is used to position the housing ends. The flat plate establishes the pinion centerline and is used as a convenient locator for checking housing-end position. Here is the Mittler tool, with the 11⁄2-inch mandrel bar and the adapters. The kit comes w Per the instructions, we bolted the flat plate to the housing. The slot is used to hook your tape measure for measuring the housing-end length. On the Camaro 12-bolt, the passenger side measures 261⁄2 inches, while the driver side measures 271⁄2 inches in length from the pinion centerline. The slot is used to hook your tape measure for measuring the housing-end length. On the Ca Mittler Brothers offers a blank layout chart to help with measuring the housing. Since the passenger side is 1 inch shorter than the driver side on our Camaro rearend, this produces a 1⁄2-inch pinion offset, which is common for most GM rearends. The example shown here is for a Ford housing with a 2-inch difference in axle length, creating a 1-inch pinion offset. Clearly, this tool can also be used for narrowing rear-end housings and therefore changing the pinion offset if necessary. Mittler Brothers offers a blank layout chart to help with measuring the housing. Since the Moore used his Lamb Components digital angle finder to establish the position of the stock housing ends so he could duplicate the location with the new housing ends. Moore used bolts to locate the angle finder because they were more accurate than the flat portion of the housing ends and also because the Strange housing ends did not offer a flat machined surface for this purpose. The GM bolt pattern is asymmetrical, so you want to make sure the new housing ends are oriented the same way as the originals. Our ends measured -4.9 degrees from horizontal, with the large bolt spacing at the top. Moore used his Lamb Components digital angle finder to establish the position of the stock Moore measured the length of the Strange housing end and then marked the housing where it needed to be cut. Mittler suggests using a large cut-off wheel to remove the original housing ends. Moore’s saw could not make the cut in one step due to clearance problems between the saw and the leaf-spring mounts, so he had to make two cuts on each end. The biggest challenge was ensuring that the housing was exactly 90 degrees to the cut-off wheel. Moore measured the length of the Strange housing end and then marked the housing where it Making the final cut, a light feed to the cut-off wheel ensures a straight cut. This takes time because the 12-bolt housing uses 0.375-inch-wall-thickness tubing. Making the final cut, a light feed to the cut-off wheel ensures a straight cut. This takes Using the Mittler 12-bolt Chevy adapters in the bearing bores, Moore tightened the differential bearing caps in place to locate the mandrel. Using the Mittler 12-bolt Chevy adapters in the bearing bores, Moore tightened the differe Moore dressed and lightly chamfered the housing to create a mild “V” to ensure a strong weld. He then double-checked the housing-end positions using Mittler’s pinion centerline plate and then clocked each end in the same position as the stock housing ends. Moore dressed and lightly chamfered the housing to create a mild “V” to ensure a strong we Next, Moore tacked both housing ends using the mandrel and adapters to hold the housing end in place. Mittler suggests tacking the housing end to the housing using four equally spaced positions. Next, Moore tacked both housing ends using the mandrel and adapters to hold the housing en After checking the positions of the housing ends one final time, Moore used his Lincoln 180C 220-volt MIG welder to weld the housing ends. He welded in short sections of roughly 2 inches in length, alternating from side to side until both ends were fully welded in place. After checking the positions of the housing ends one final time, Moore used his Lincoln 18 This is the final weld. The mandrel easily slides in and out of the adapters after the ends were welded on, ensuring the ends are accurately placed. The axles will now be securely attached to the housing with the retaining strap and bolts—far safer than those spindly C-clips. Next, we will thoroughly clean the housing, powdercoat it, and then it will be ready to assemble with a set of Strange 3.55:1 gears, a Strange limited-slip, and the Strange axles. End This is the final weld. The mandrel easily slides in and out of the adapters after the end By Jeff Smith Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!