The debates are common: Ford 9-inch vs 12 bolt, or maybe even Dana 60 vs Ford 9-inch. Which one reigns supreme?
When it comes to high-performance horsepower, the factory differential is usually living on borrowed time. Choosing the right foundation for a custom rear end upgrade is a critical decision for your build. But the truth is, there is no single best rear end – only the best rear end for your specific application.
Let’s break down the big three heavyweights in the aftermarket driveline world so you can figure out the best rear end for drag racing, autocross, or your weekend street build.
The Heavyweight Contenders
The Ford 9-Inch
The Ford 9-inch is the undisputed king of versatility and aftermarket support. Even die-hard Chevy and Mopar fans will routinely stuff a 9-inch under their cars, and for good reason.
- The Pros: The biggest advantage of the 9-inch is its drop-out center section (the “third member”). You can set up your gears on a workbench rather than crawling under the car, making gear swaps incredibly fast at the track. It also features an additional bearing that supports the pinion gear, greatly reducing gear deflection during heavy launches.
- The Cons: Because the pinion gear meshes much lower on the ring gear than other designs, it creates more sliding friction. This results in a slight parasitic horsepower loss (meaning a little less power reaches the tires) and causes the rear end to run slightly hotter.
- The Verdict: If you want infinite gear ratios, lots of adjustability, and a rear end that can handle abuse, the 9-inch (like our custom Moser M9) is the gold standard.
The Chevy 12-Bolt
The Chevy 12-bolt is a piece of GM muscle car history. It’s an integral-style rear end, meaning the gear set is housed directly inside the main axle housing with a bolt-on rear cover.
- The Pros: The 12-bolt is incredibly efficient. Because the pinion gear sits closer to the centerline of the ring gear, it takes less energy to turn. This means less parasitic power loss compared to a 9-inch. It’s also physically lighter, which is a huge bonus for optimizing unsprung weight.
- The Cons: In factory form, Chevy 12-bolts rely on C-clips to hold the axles in place – a major safety hazard if an axle breaks. (Don’t worry, we fix this with press-on bearings and C-clip eliminators, making them track-legal). Gear swaps also require pulling the cover and setting the backlash while the car is on the ground.
- The Verdict: Perfect for GM purists, restorations, and high-performance street/strip cars where maximizing every ounce of horsepower to the ground is a top priority.
The Dana 60
Originally designed for heavy-duty trucks, the Dana 60 (also famous as the big brother to the Mopar 8 ¾”) is the brute-force option of the group.
- The Pros: Raw strength. Featuring a massive 9.75-inch ring gear and a rigid cast center section, the Dana 60 is practically indestructible. The straight-line pinion gear mesh makes it surprisingly efficient, rivaling the 12-bolt for low parasitic drag.
- The Cons: It is the heaviest of the three. It’s physically bulky, which can sometimes create clearance issues in smaller chassis or cars with lowered suspensions.
- The Verdict: If you have a heavy car, a transbrake, and a big block that dumps mountains of torque, the Dana 60 is your set-it-and-forget-it solution.
Ready to Upgrade? Let Moser Build It.
Knowing which rear end to choose is only half the battle. Getting it built right, built fast, and built to handle massive horsepower is what we do.
Moser Engineering has been racer-owned and track-proven since 1986. We custom-build rear ends and axle assemblies every single day right here in the USA, using US-forged steel machined in our Indiana facility.
Why Choose a Moser Custom Rear End?
- Lightning Fast Turnarounds: We build and ship most custom axles and complete rear-end kits in 2 business days or less.
- Plug-and-Play MUSCLE PAKS: Don’t want to mess with sourcing brakes, gears, and bearings? Order a Moser MUSCLE PAK. It’s a fully assembled, drop-in rear-end package built to your exact specs, and it hooks right up to your factory mounting points.
- NHRA Track-Legal: We ditch the dangerous factory C-clips and use press-on bearings, meaning your new custom rear end will pass tech inspection and keep you safe when it counts.
Whether you need a bulletproof M9, a hyper-efficient 12-Bolt, or an indestructible Dana 60, we have the exact setup your chassis needs. Contact us with questions, and order today.