Face it, you'd have a better chance of finding an honest Congressman than you would of discovering a used 12-bolt rear axle assembly in the junkyard. Sadly, the days of stumbling onto 12 bolt rear ends are over. If you really want a 12 bolt rear end, the easiest find is an aftermarket housing from Moser, but be prepared to spend upwards of $2,500 for a complete, road-ready rear end. For those willing to spend the time looking for a nearly-as-strong housing for an early Camaro or Firebird, tune your search radar to '72 to '75 Novas that all came stock with 8.5-inch 10-bolt rear ends. This is not a new idea, and we've covered this strategy several times in the past. What is new is how to set up one of these rear endss with far less effort and make it stronger without spending big bucks. There are two big hassles with setting gears in a GM rear ends. The first is establishing the proper pinion depth to get a good pattern and then using 300 to perhaps 400 ft-lb of torque to set the pinion bearing preload. You probably know the drill: Most guys use a pneumatic impact gun, but that is hard on the pinion bearings. We've actually broken a 1/2-inch drive breaker bar (using a 3-foot-long cheater bar) in an attempt to set the preload. The problem is the design of the crush sleeve. Ratech has come up with a much cleaner version called the Smart Sleeve, which requires less than half the torque (about 120 to 150 ft-lb) and nearly doubles the range the sleeve can be compressed from the stock amount of about 0.040 to 0.060 inch to 0.095 inch. The Smart Sleeve also has great cycle stability, as it's a more compact design. This makes swapping gears into the 10 bolt rear ends much easier. We have a couple of other really slick ideas that help here. Ratech makes a great pinion depth installation tool that works really well for aftermarket gears. But what happens when you want to swap in stock gears that don't have a pinion depth noted on the pinion? We've found the best place to start is to reuse the stock pinion shim that's located between the pinion gear and the bearing. Since all hypoid gears are lapped in on the gear machine using the same pinion depth relationship, the shim on a factory ring-and-pinion installation is used to accommodate the difference in pinion depth between housings. So it stands to reason that using the same-thickness pinion shim will deliver a gear-tooth pattern very close to ideal. The great thing about this GM 10-bolt is that you can easily find gears and sometimes limited-slip units from '77 to '94 Chevy half-ton pickups and vans that use the same 8.5-inch 10-bolt rear axle. This makes finding a 3.42:1 gearset much easier and less expensive. We're using a 12-bolt replacement crush sleeve on the left for comparison with the Smart Sleeve on the right. The 12-bolt- version Smart Sleeve uses a thick spacer to make up the difference in length. The Smart Sleeve crushes with far less torque, making it much easier to establish the proper bearing preload. We're using a 12-bolt replacement crush sleeve on the left for comparison with the Smart S Setting the pinion depth generally involves pressing the pinion bearing on and off multiple times until you find the correct depth. But if you use an abrasive flapper wheel on the inside diameter of a pair of used pinion bearings until they will slip over the pinion, you can pretest for proper pinion depth, then press new bearings on the pinion with the proper shim. Setting the pinion depth generally involves pressing the pinion bearing on and off multipl Here is the Smart Sleeve installed on the pinion with the yoke. This is Ratech's budget pinion-depth tool. There are individual tools for all the popular housings. What makes this tool unique is that it establishes the actual centerline of the ring-gear carrier. It does not use the parting line of the main caps, as that is rarely the true centerline. Send us an email if you'd like to see a story on how to set up pinion depth, even on nonmarked factory gears. This is Ratech's budget pinion-depth tool. There are individual tools for all the popular Ratech also makes a solid-pinion bearing spacer. It works by installing the sleeve with a few thick shims and duplicating the length of the used crush sleeve, removing or exchanging for thinner shims, and then tightening until the proper preload is achieved. This is a great because if you have to remove the pinion to replace a leaking pinion seal, the pinion preload is already set. Ratech also makes a solid-pinion bearing spacer. It works by installing the sleeve with a This is another Ratech tool we found useful. It is a combination yoke-holding tool that allows you to securely position the yoke while torquing the pinion preload. The combination tool is also a pinion remover, as show here. Very cool. This is another Ratech tool we found useful. It is a combination yoke-holding tool that al SOURCES Ratech 513-742-2111 http://www.ratechmfg.com By Jeff Smith Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!