9-Inch Crate Rear End - Rear It All Ends

Picture this: the planets have aligned to bring together the perfect combination of sticky track, sticky tires, and your fresh bitchin' big-block. After heating the tires and staging, the lights come down and you drop the hammer. Instead of launching, there's a horrible bang from behind, and you ain't goin' nowhere. Congratulations friend-you just broke your junk, and made a huge mess on the track. We've seen it a hundred times, and it's still not cool. Slightly less embarrassing, but just as inconvenient, are those untimely episodes on the street where wheel hop snaps axles and breaks rearend gear teeth. Ouch!

Our Street Sweeper '68 Chevelle project is the type of car-heavy and (soon to be) powerful-that is a prime candidate for this kind of misbehavior. Endowed from the factory with GM's corporate 8.2-inch 10-bolt rear, this Malibu would be headed for a date with the tow truck if it were to encounter the 600-plus horsepower big-block we're planning for it. And while our Chevelle may indeed find itself on the wrong end of the hook some day, it won't be from an exploded rearend-thanks to all-new hardware we're getting from Currie Enterprises.

Before making our move to Currie, we weighed our options carefully. One of our first ideas was to go with a '71-and-later 10-bolt, which has the larger, stronger 8.5-inch ring gear (the same rear that's in our lighter and less powerful '76 Camaro, Project g/28). Although it's super cheap, it would still require modification with a stronger differential and axles. Even in the best case, it would be marginal in a 3,800-pound car running 11s.

We quickly opted to leave the game of rearend roulette to Car Craft. A GM 12-bolt is far stronger, and is well supported by the aftermarket. It's a good choice that's up to the task, but the decision to go with a Ford 9-inch was based on one more fact: For about the same price as a built 12-bolt, we could get a built 9-inch with all new parts. The Ford 9-inch rear is significantly different than either the 10- or 12-bolt; instead of having a cast iron center section that has steel tubes wedged and welded to it, the entire housing is formed steel, from end to end. The third member of a Ford 9-inch is not burdened by the torsional loads from the axle tubes, and can easily be removed for maintenance. Additional third members may also be set up with different gear ratios or differential types, for smooth swapping at the track-no need for shim packs, dial indicators, or crush sleeves. On the downside, there's a small penalty in mass and mechanical efficiency relative to the GM 12-bolt.

Currie-Built Crate Rearend
If you're serious enough to consider a bomb-proof rearend like a 9-inch, you likely have a pretty good idea of what you need, and how much you want to spend. Surprisingly, that is a pretty good argument for not buying a ready-made, pre-assembled unit. (Why buy stuff you don't need, or leave out something you do?) The Currie-Built Crate Rearend comes to your door unassembled, via UPS. The advantage of this is twofold: You don't have the added cost and inconvenience of having your rear shipped by truck freight (the individual parts are below the UPS weight threshold), and you don't have to wait weeks or months for it, since Currie plucks the parts off the shelf the day you order it. If you don't mind waiting, Currie can ship your rearend assembled, but it will take three weeks instead of the two to three days it normally takes to ship modular kits.