Deep Dive: General Motors’ G80 Locking Rear Differential
General Motors has been offering an automatic locking rear differential in its Chevy and GMC trucks for more than 40 years. Today, its prevalence has grown to include every body-on-frame, rear-drive vehicle in GM’s lineup – from the Colorado WT up through the leather-lined Cadillac Escalade. And thanks to its order code, most folks know the mechanical locker as the Eaton G80. Here’s how it works.
The G80 is a specialized differential designed by Eaton to work as a low-speed traction aid, offering full lockup during its operation. When in normal conditions, the unit acts as an open differential, letting the rear tires spin independently of each other, with the outside wheel spinning faster during turns. However, when one tire spins 120 rpm faster than the other, the G80 locker kicks into action.
As the video above shows, the difference in rpm actuates a flyweight-type governor, slinging a pawl that engages a clutch system, which then causes a cam plate to ramp against a side gear, compressing the disc pack. This action locks together both axle shafts, and therefore makes both wheels rotate at the same speed. Eaton has included two such actuating pawls, allowing the G80 to work in both forward and reverse gears.
Simply put, the G80 engages automatically and without driver input to evenly distribute power both rear wheels. This is in contrast to other systems as Ford’s or Ram’s E-Lockers, which require the driver to engage the system electronically from the cabin. While there’s pros and cons to both systems, the Eaton G80 does take the cake for simplicity for the driver.
Continue reading to learn more about the Eaton G80 Locker.
General Motors offers the Eaton G80 automatic locking rear differential on all its body-on-frame SUVs and trucks – either as standard equipment or as an optional extra. What’s more, 4WD is not necessary to order the G80.
Currently, the G80 is offered on the Colorado and Canyon; Silverado and Sierra; Tahoe and Yukon; Suburban and Yukon XL; and the Escalade. Both the Z71 and All-Terrain packages, along with many of the upper trim lines, come included with the G80, while other trims offer it as an option.
Why it matters
Speaking from personal experience, the G80 works well at providing the extra traction needed to get through sticky situations. There’s been plenty of times the G80 in my personal vehicle has saved me from calling for a tow. The only real downside is the Eaton’s somewhat clunky operation at high-rpm engagement. There are also reports floating around that suggest oversized tires mixed with an over-zealous right foot will lead to exploding pumpkins. But for the majority of consumers, the G80 works as a decent alternative to aftermarket lockers, limited-slip differentials, or perhaps even 4WD. After all, there must be a reason GM has stuck with Eaton’s design for 40 some years.