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Inside GM’s most popular locking differential; getting traction when traction is needed most
Trucks need traction to get the job done. And whether it is winter snow, spring mud or the weed-covered boat ramps of summer, a facotry-installed automatic-locking rear axle can help keep Chevy/GMC trucks moving ahead with enhanced confidence and control.
Often referred to as the G80 for its order code, the rear axle locks automatically if one wheel starts to spin, enabling both rear wheels to propel the truck.
The added traction lets a 2WD pickup to go places traditionally thought of as 4×4 territory, and further enhances the capability of 4×4 pickups.
“The G80 locking axle provides a greater traction advantage than limited-slip differentials in most situations, while its automatic engagement requires no driver involvement, unlike some competitors’ electronic lockers, which require driver activation,” said Jeff Luke, executive chief engineer.
“The G80’s simplicity, durability and sure-footed grip have been proven with generations of customers, as it has been a staple of the Chevy truck lineup for more than 40 years.”
The G80 automatic locking rear axle is available on most Silverado models, and is standard on LTZ and Z71 versions of the Silverado 1500 and all Silverado 2500 and 3500 HDs.
Additionally, it is available on Colorado WT and LT models, and standard on Colorado Z71. It is also standard on Tahoe and Suburban.
With technology by Eaton, the G80 performs as an open differential until excessive slip in one wheel automatically triggers the locking mechanism, ensuring the rear wheels turn at the same speed.
It provides more sure-footed traction than a conventional limited-slip axle, which can allow the wheels to turn at different rates in a low-traction environment, limiting the amount of traction-enhancing torque that can be channeled to the faster-spinning wheel. Unlike electronic lockers, the G80 engages and disengages automatically, with no input from the driver.
When the G80 detects excessive wheel slip, a flyweight-type governor engages. A self-energized clutch system causes a cam plate to ramp against a side gear, compressing disc pack to cause both rear axle shafts/wheels to rotate at the same speed.
The lockup and disengagement processes happen instantly and are practically imperceptible to the driver. Ride is smoother because the G80 operates mostly as an open-type differential in normal driving conditions.
“There are no buttons to push or electronic settings to engage,” said Luke. “The G80 does its job instantly and quietly, so drivers can go about their job with confidence.”