RPO Code G80 – We Explain What It Means and How to Deal with It

RPO code G80 is a common term used on American pickup trucks. It is a term often thrown around by truck owners, and the ordinary driver or person will get lost trying to catch up in the conversation. Our article today demystifies what RPO code G80 means and how one can best benefit from using it.

Regular Production Option or RPO, as it is commonly called, is a General Motors standard of coding employed since the 1970s. The carmaker uses alphanumeric codes to refer to a particular option in a vehicle or even a modification. Rather than use words or long sentences to describe color, engine component, or system, these codes are used. The GM rear locking differential has, over time, adopted the cool name, G80. In our case, we dwell on the RPO G80 code.

What does RPO G80 mean?

RPO G80 is the code used to refer to the rear lock differential by GM. The rear differential is a component that makes a 2WD pickup venture into 4x4 territory with more control and confidence. The G80 is an automatic lock differential that detects when one of the wheels starts spinning and locks both wheels 100%. This allows both wheels of the same axle to spin together, propelling the truck.

Many work pickups are rear-powered, and GM trucks are no exception. Normally, the truck will operate with an open differential. This means the rear axle is the one propelling the truck, and whenever you find yourself in a snowy or muddy situation, the G80 code locks and prevents or stops a single rear wheel from spinning because of lack of traction.

The RPO G80 is very useful for drivers who venture out on muddy roads. Though a big boost for the 2WD vehicles, it also enhances the capability of 4x4s. A 4x4 can have two differentials for each of its axles. The G80 is available on most Silverado models, Colorado WT, and LT. The G80 is not a preserve for trucks nowadays, but you can have it as an option in cars such as the Cadillac Escalade.

G80 rear differential is made by Eaton, an American company established in 1922. The company has become a leader in differentials, superchargers, traction control, clutches, hydraulic motors, server racks, etc. The RPO G80 offers the best traction for the everyday driver and doesn't need to go for a four-wheel drive when they got this rear differential.

How does the G80 work?

Moving around a ranch or driving in the outback where patches of mud and water are present, you need a reliable truck. GM armed their trucks with the G80 code, which ensures that when one of the wheels to an axle powered by the engine spins, it locks the wheels. The sensors are set to lock the differential once one wheel spins more than the other by 120 RPMs.

Unlike other trucks like RAM or Ford, where the driver is required to engage the differential from the cabin, the G80 engages automatically. The driver doesn't have to do anything. A flyweight-like governor slings a pawl to engage a clutch when a difference in RPMs is detected in the wheels. The engaged clutch system will cause the cam plate to press against a side gear, pressing the disc pack. This action is what locks the two axles shafts of an axle. This then makes the wheels rotate at the same speed.

For the driver who prefers to know the technical way the G80 works, when one wheel slips faster than the other by 120 RPMs, the G80 engages. The PAWLS, small ratcheting teeth, open up to catch the latch, which then initiates the locking sequence to lock up the axle 100%. The G80 will automatically unlock once it's no longer needed. All this happens in a matter of a fraction of a second.

The Eaton G80 rear lock differential, also referred to as the MLocker mechanical locking differential at Eaton, offers a driver the best possible traction on the road without needing to push any buttons. The system applies a flyweight mechanism and a self-energizing clutch system which engages in low traction situations.

The G80 system detects when one wheel of an axle spins 120 rpms more than the other and swings into action within a fraction of a second. This makes driving a vehicle easy and fun on icy, mud, or gravel roads. The RPO G80 works perfectly well with existing vehicle stability and anti-brake systems. This makes matters easy as platform integration is simplified for the use of all manner of OEMs.

When is G80 most ideal?

A driver will enjoy the most out of their G80 in the following situations;

• When starting off their truck
• When tackling steep grades
• On muddy or icy roads
• When cornering

What makes the RPO G80 unique?

A GM work pickup will confidently venture off the beaten path in the woods or the countryside. This being the case, such a pickup cannot perform optimally without this contraption, called the G80. The G80 affords the driver of a pickup control and traction just the same as or nearly that enjoyed by a four-wheel. But remember, for enhanced versatility, four-wheel trucks can be equipped with G80.

The one thing that makes G80 so effective and loved by pickup truck drivers is its effective 100% locking of the wheels. This gives both rear wheels maximum power when most needed. No matter the muddy situation you are in, you are unlikely ever to need the services of a towing company.

When you put G80 and limited slip-differential side by side, you will notice that G80 affords the wheels far better traction in the shortest time. Another thing about the G80 is that it doesn't require the driver's input to engage and pull you out of a muddy situation. This diff lock operates in an open differential and only locks up when it detects a wheel slip.

Difference between open and locked differential

To better understand G80 and how it works, we will take a sneak view into what open differential means and the difference it has with a locked differential such as the G80.

• Open differential

The open differential is fitted on most road cars. It allows the wheels to rotate at different speeds when the car is turning a corner. Open differential splits engine torque evenly between the wheels, which means that both wheels have even amounts of power. When taking a corner, the outer wheel of the car has to travel further than the inner one. The outer wheel requires more power to travel the extra distance. An open differential won't work well on a slippery surface since engine torque is sent to the wheel with the least resistance or traction. 

• Locked differential

A locked differential such as G80 will kick in when one wheel turns significantly more than the other. The system will kick in and lock both wheels, forcing them to spin at the same rate. However, the differential allows for uneven distribution of torque. It allows for a 100% torque transfer to either wheel, which always allows maximum torque to be applied.

A locked differential can transfer all the torque from both the right and left wheels. Where needed, a significant amount of torque is transferred to the ground, which can make a difference between moving out of a tricky situation. This is why it is most effective on pickups.

RPO G80 code issues

• Being able to lock up both wheels 100% comes with serious handling issues. Your truck will likely give you issues with understeering when making a turn. This is caused when both rear wheels lose traction and start sliding, which then causes oversteering.
• Another issue worth noting is that the G80 will make the truck more likely to oversteer when accelerating. This makes the vehicle hard to control, unpredictable, and, at times, dangerous.
• With a rear differential, both wheels are locked together. When making a turn, you will likely experience skipping, screeching, and hopping from the rear-end wheels as they struggle to maintain traction. When this happens, premature wear and tear of the tires happen. The driveshaft also gets subjected to a lot of strain.

Conclusion

The RPO G80 code is a best seller for Eaton, not only because it is included in GM's top-of-the-range trucks but because Eaton has over a century of experience. Over the years, the company has added tweaks and changes to this rear-wheel differential system. GM has stuck with Eaton for over four decades, evidence of the G80's reliability.

This differential is guaranteed to take you across plains, even where the mud will make ordinary vehicles struggle and get stuck. With G80, the need to call the tow company fades into oblivion because it makes your truck more than capable. Moreover, you don't have to push a single button or move a gear to make all this magic happen. Just step on the gas and observe G80 do its thing.