Stuck Locker

[Brenau1959]

Any ideas on how to unlock a locked g80? Today on patch of ice at stop light, started off and one rear wheel slipped, heard clunk and began moving. Now in a turn the rear seems to bind... stutter. It is almost the same sensation you get in 4WD on dry pavement, Any suggestions. 2008 silverado, 30k miles 4wd crew cab 1/2 ton LTZ

[ColoradoSkiCountry]

Try driving it in backwards a bit. If that doesn't work, get her over to the dealer. The G-80 probably blew up.. Yes even at 30,000 miles. They work well when they work but they are not durable as I and a few others on here have found out. At least yours will be under warranty. Mine went out at 90,000 miles and $1600 later I had a new diff.

[Nytemare]

Its weird...it really seems to be hit and miss with these lockers and 10 bolt rears. I know people with no issues...and some guys that are on they're third. My friend has an 870RWTQ Avalanche...and his is fine...cant keep tranny's in the damn thing...but the diff is holding strong.

[Daryl LBZ]

This happened to me the other night at work. I hit a patch of ice and it locked, while making a loud bang. I backed into a parking spot and it was binding, same thing when I pulled out. I dropped it in 4wd then back out, went down the parking lot and made a right turn and it made a loud bang again and unlocked. Haven't had any trouble since.

[bik838]

Try putting the truck into 4wd low, since it locks the rear up in low, drive it around for a min then take it out of low gear back into 2wd should unlock it. I had mine do the same thing one night.

[KMGZ400]

this may sound stupid, but when my locker is stuck i get the tires to break loose and it will always smoothly unlock

[clemsonblozz]

4 Lo doesn't do anything to the locker.. The G80 locks when it see's a 200 RPM differental between the two wheels.. I think after 20 or 30 mph it will not lock, and I think it's supposed to unlock..

 

The locker operates off centrifugal force, not signals from the truck, tranny or t-case..

[Nytemare]

4 Lo doesn't do anything to the locker.. The G80 locks when it see's a 200 RPM differental between the two wheels.. I think after 20 or 30 mph it will not lock, and I think it's supposed to unlock..

 

The locker operates off centrifugal force, not signals from the truck, tranny or t-case..

Exactly right...except its a 100 rpm difference.

[Silverado4x4]

Try putting the truck into 4wd low, since it locks the rear up in low, drive it around for a min then take it out of low gear back into 2wd should unlock it. I had mine do the same thing one night.

 

Putting it in 4WD has nothing to do with the rear locking. To the orignal poster did you change rear fluids and not put the right lub in? The G80 requires a special lub additive and it is possible the fluid could be low from the dealer as I have heard of this and the dealer didnt check all fluids when the truck came to the dealer as there suppose to. All lockers act strange sometimes.

[dlstewart01]

Try putting the truck into 4wd low, since it locks the rear up in low, drive it around for a min then take it out of low gear back into 2wd should unlock it. I had mine do the same thing one night.

 

Putting it in 4WD has nothing to do with the rear locking. To the orignal poster did you change rear fluids and not put the right lub in? The G80 requires a special lub additive and it is possible the fluid could be low from the dealer as I have heard of this and the dealer didnt check all fluids when the truck came to the dealer as there suppose to. All lockers act strange sometimes.

 

 

G80 in cars are limited slip. and require a limited slip additive. G80s in trucks are lockers and donot require an additive. See this bulletin from General Motors...

 

LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109

SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)

VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS

Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.

This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.

To correct this condition, drain and refill the rear axle with SAE 75-W-90 GL5 (P/N 12378557). The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.VEHICLES/COMPONENTS INVOLVED: ----------------------------- Some light duty trucks equipped with locking rear axles, RPO G80.

SERVICE PARTS INFORMATION:

Part Number Description ----------- ------------------ 12378261Lubricant, synthetic, Rear Axle (1 litre)

Parts are currently available through CANSPO.

WARRANTY INFORMATION:

As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.

© Copyright General Motors Corporation. All Rights Reserved.

[ybsane]

4 Lo doesn't do anything to the locker.. The G80 locks when it see's a 200 RPM differental between the two wheels.. I think after 20 or 30 mph it will not lock, and I think it's supposed to unlock..

 

The locker operates off centrifugal force, not signals from the truck, tranny or t-case..

Exactly right...except its a 100 rpm difference.

 

 

 

Sorry, but a locker does not work that way. Lockers stay locked together like a spool when you are driving staight all the time, they un-lock in a ratchet type action when you make a turn so you don't hop or bark the tires in a corner.

 

Limited slip will allow locking when there is a difference in speeds causing the clutch packs to bind tighter together, the only differential that stays locked into corners and also straight line that I've seen are the Gleason Torsen differentials.

 

Just speaking from experience from doing differential's years ago, but did not know about the lockers for the newer style trucks. The only ones that I knew of where for the Corporate 14-bolts and having to get an after market locker or spool with a c-clip eliminator for the 10/12-bolt rears.

[dlstewart01]

4 Lo doesn't do anything to the locker.. The G80 locks when it see's a 200 RPM differental between the two wheels.. I think after 20 or 30 mph it will not lock, and I think it's supposed to unlock..

 

The locker operates off centrifugal force, not signals from the truck, tranny or t-case..

Exactly right...except its a 100 rpm difference.

 

 

 

Sorry, but a locker does not work that way. Lockers stay locked together like a spool when you are driving staight all the time, they un-lock in a ratchet type action when you make a turn so you don't hop or bark the tires in a corner.

 

Limited slip will allow locking when there is a difference in speeds causing the clutch packs to bind tighter together, the only differential that stays locked into corners and also straight line that I've seen are the Gleason Torsen differentials.

 

Just speaking from experience from doing differential's years ago, but did not know about the lockers for the newer style trucks. The only ones that I knew of where for the Corporate 14-bolts and having to get an after market locker or spool with a c-clip eliminator for the 10/12-bolt rears.

 

 

 

Well ole buddy... see GMs explination of the G80 eation guv lock...

 

and see video

http://www.youtube.com/watch?v=-sw9DwurQAs

 

 

When the wheel-to-wheel speed difference is 100 RPM or more, the flyweights of the governor will fling out and one of them will contact an edge of the latching bracket. This happens because the left cam side gear and cam plate are rotating at a speed different, either slower or faster, than that of the ring gear and differential case assembly. The cam plate has teeth on its outer diameter surface in mesh with teeth on the shaft of the governor.

 

As the side gear rotates at a speed different than that of the differential case, the shaft of the governor rotates with enough speed to force the flyweights outward against spring tension. One of the flyweights catches its edge on the closest edge of the latching bracket, which is stationary in the differential case. This latching process triggers a chain of events.

 

When the governor latches, it stops rotating. A small friction clutch inside the governor allows rotation, with resistance, of the governor shaft while one flyweight is held to the differential case through the latching bracket. The purpose of the governor's latching action is to slow the rotation of the cam plate as compared to the cam side gear. This will cause the cam plate to move out of its detent position.

 

The cam plate normally is held in its detent position by a small wave spring and detent humps resting in matching notches of the cam side gear. At this point, the ramps of the cam plate ride up on the ramps of the cam side gear, and the cam plate compresses the left clutch pack with a self-energizing action.

 

As the left clutch pack is compressed, it pushes the cam plate and cam side gear slightly toward the right side of the differential case. This movement of the cam side gear pushes the thrust block which compresses the right-hand side gear clutch pack.

 

At this point, the force of the self-energizing clutches and the side gear separating force combine to hold the side gears to the differential case in the locking stage.

 

The entire locking process occurs in less than 1 second. The process works with either the left or right wheel spinning, due to the design of the governor and cam mechanism. A torque reversal of any kind will unlatch the governor, causing the cam plate to ride back down to its detent position. Cornering or deceleration during a transmission shift will cause a torque reversal of this type. The differential unit returns to its open diff function.

 

The self-energizing process would not occur if it were not for the action of one of the left clutch discs. This energizing disc provides the holding force of the ramping action to occur. It is the only disc which is splined to the cam plate itself. The other splined discs fit on the cam side gear.

 

If the rotating speed of the ring gear and differential case assembly is high enough, the latching bracket will pivot due to centrifugal force. This will move the flyweights so that no locking is permitted. During vehicle driving, this happens at approximately 32 km/h (20 mph) and continues at faster speeds.

 

When comparing the effectiveness of the locking differential, in terms of percent-of-grade capability to open and limited-slip units, the locking differential has nearly 3 times the potential of the limited-slip unit under the same conditions

[Nytemare]

4 Lo doesn't do anything to the locker.. The G80 locks when it see's a 200 RPM differental between the two wheels.. I think after 20 or 30 mph it will not lock, and I think it's supposed to unlock..

 

The locker operates off centrifugal force, not signals from the truck, tranny or t-case..

Exactly right...except its a 100 rpm difference.

 

 

 

Sorry, but a locker does not work that way. Lockers stay locked together like a spool when you are driving staight all the time, they un-lock in a ratchet type action when you make a turn so you don't hop or bark the tires in a corner.

 

Limited slip will allow locking when there is a difference in speeds causing the clutch packs to bind tighter together, the only differential that stays locked into corners and also straight line that I've seen are the Gleason Torsen differentials.

 

Just speaking from experience from doing differential's years ago, but did not know about the lockers for the newer style trucks. The only ones that I knew of where for the Corporate 14-bolts and having to get an after market locker or spool with a c-clip eliminator for the 10/12-bolt rears.

 

 

WOW...really...you've never heard of an Eaton mechanical locker?

 

mechanical locker...locks when wheel spin is detected over X amount of wheel RPM...also known as a locking rearend...its been around for 40 years at least..detroit true trac works very similar to this also. The confusion comes from the G80 code, cars with G80 have an LSD..trucks get a locking diff...the same code is on the 10, 12 1nd 14 bolts but they are different lockers...but only in size..they still work the same.

 

LSD never locks...it applies spring pressure to clutches causing both wheels to turn at the same speed.

 

the locker your thinking about is a detroit locker...it stays locked and tries to separate around corners...also falling in this category is the Lockrite which has lighter springs allowing the locker to separate easier in corners and not give that crunchy sound and jitter.

[ybsane]

4 Lo doesn't do anything to the locker.. The G80 locks when it see's a 200 RPM differental between the two wheels.. I think after 20 or 30 mph it will not lock, and I think it's supposed to unlock..

 

The locker operates off centrifugal force, not signals from the truck, tranny or t-case..

Exactly right...except its a 100 rpm difference.

 

 

 

Sorry, but a locker does not work that way. Lockers stay locked together like a spool when you are driving staight all the time, they un-lock in a ratchet type action when you make a turn so you don't hop or bark the tires in a corner.

 

Limited slip will allow locking when there is a difference in speeds causing the clutch packs to bind tighter together, the only differential that stays locked into corners and also straight line that I've seen are the Gleason Torsen differentials.

 

Just speaking from experience from doing differential's years ago, but did not know about the lockers for the newer style trucks. The only ones that I knew of where for the Corporate 14-bolts and having to get an after market locker or spool with a c-clip eliminator for the 10/12-bolt rears.

 

 

 

Well ole buddy... see GMs explination of the G80 eation guv lock...

 

and see video

http://www.youtube.com/watch?v=-sw9DwurQAs

 

 

When the wheel-to-wheel speed difference is 100 RPM or more, the flyweights of the governor will fling out and one of them will contact an edge of the latching bracket. This happens because the left cam side gear and cam plate are rotating at a speed different, either slower or faster, than that of the ring gear and differential case assembly. The cam plate has teeth on its outer diameter surface in mesh with teeth on the shaft of the governor.

 

As the side gear rotates at a speed different than that of the differential case, the shaft of the governor rotates with enough speed to force the flyweights outward against spring tension. One of the flyweights catches its edge on the closest edge of the latching bracket, which is stationary in the differential case. This latching process triggers a chain of events.

 

When the governor latches, it stops rotating. A small friction clutch inside the governor allows rotation, with resistance, of the governor shaft while one flyweight is held to the differential case through the latching bracket. The purpose of the governor's latching action is to slow the rotation of the cam plate as compared to the cam side gear. This will cause the cam plate to move out of its detent position.

 

The cam plate normally is held in its detent position by a small wave spring and detent humps resting in matching notches of the cam side gear. At this point, the ramps of the cam plate ride up on the ramps of the cam side gear, and the cam plate compresses the left clutch pack with a self-energizing action.

 

As the left clutch pack is compressed, it pushes the cam plate and cam side gear slightly toward the right side of the differential case. This movement of the cam side gear pushes the thrust block which compresses the right-hand side gear clutch pack.

 

At this point, the force of the self-energizing clutches and the side gear separating force combine to hold the side gears to the differential case in the locking stage.

 

The entire locking process occurs in less than 1 second. The process works with either the left or right wheel spinning, due to the design of the governor and cam mechanism. A torque reversal of any kind will unlatch the governor, causing the cam plate to ride back down to its detent position. Cornering or deceleration during a transmission shift will cause a torque reversal of this type. The differential unit returns to its open diff function.

 

The self-energizing process would not occur if it were not for the action of one of the left clutch discs. This energizing disc provides the holding force of the ramping action to occur. It is the only disc which is splined to the cam plate itself. The other splined discs fit on the cam side gear.

 

If the rotating speed of the ring gear and differential case assembly is high enough, the latching bracket will pivot due to centrifugal force. This will move the flyweights so that no locking is permitted. During vehicle driving, this happens at approximately 32 km/h (20 mph) and continues at faster speeds.

 

When comparing the effectiveness of the locking differential, in terms of percent-of-grade capability to open and limited-slip units, the locking differential has nearly 3 times the potential of the limited-slip unit under the same conditions

 

 

I hear you, but thats not a locker..!! That style is called a Gov-Lock and they are the crappiest so-called locking devices I've ever seen. I understand GM calls it a Locker but its not, I would rather have a True-Trac or an Auburn limited slip than have that unit.

 

Look up Detroit Locker and see how the exploded view looks in comparison to that Gov-Lock and it will make more sense.

 

Rob

[dlstewart01]

4 Lo doesn't do anything to the locker.. The G80 locks when it see's a 200 RPM differental between the two wheels.. I think after 20 or 30 mph it will not lock, and I think it's supposed to unlock..

 

The locker operates off centrifugal force, not signals from the truck, tranny or t-case..

Exactly right...except its a 100 rpm difference.

 

 

 

Sorry, but a locker does not work that way. Lockers stay locked together like a spool when you are driving staight all the time, they un-lock in a ratchet type action when you make a turn so you don't hop or bark the tires in a corner.

 

Limited slip will allow locking when there is a difference in speeds causing the clutch packs to bind tighter together, the only differential that stays locked into corners and also straight line that I've seen are the Gleason Torsen differentials.

 

Just speaking from experience from doing differential's years ago, but did not know about the lockers for the newer style trucks. The only ones that I knew of where for the Corporate 14-bolts and having to get an after market locker or spool with a c-clip eliminator for the 10/12-bolt rears.

 

 

 

Well ole buddy... see GMs explination of the G80 eation guv lock...

 

and see video

http://www.youtube.com/watch?v=-sw9DwurQAs

 

 

When the wheel-to-wheel speed difference is 100 RPM or more, the flyweights of the governor will fling out and one of them will contact an edge of the latching bracket. This happens because the left cam side gear and cam plate are rotating at a speed different, either slower or faster, than that of the ring gear and differential case assembly. The cam plate has teeth on its outer diameter surface in mesh with teeth on the shaft of the governor.

 

As the side gear rotates at a speed different than that of the differential case, the shaft of the governor rotates with enough speed to force the flyweights outward against spring tension. One of the flyweights catches its edge on the closest edge of the latching bracket, which is stationary in the differential case. This latching process triggers a chain of events.

 

When the governor latches, it stops rotating. A small friction clutch inside the governor allows rotation, with resistance, of the governor shaft while one flyweight is held to the differential case through the latching bracket. The purpose of the governor's latching action is to slow the rotation of the cam plate as compared to the cam side gear. This will cause the cam plate to move out of its detent position.

 

The cam plate normally is held in its detent position by a small wave spring and detent humps resting in matching notches of the cam side gear. At this point, the ramps of the cam plate ride up on the ramps of the cam side gear, and the cam plate compresses the left clutch pack with a self-energizing action.

 

As the left clutch pack is compressed, it pushes the cam plate and cam side gear slightly toward the right side of the differential case. This movement of the cam side gear pushes the thrust block which compresses the right-hand side gear clutch pack.

 

At this point, the force of the self-energizing clutches and the side gear separating force combine to hold the side gears to the differential case in the locking stage.

 

The entire locking process occurs in less than 1 second. The process works with either the left or right wheel spinning, due to the design of the governor and cam mechanism. A torque reversal of any kind will unlatch the governor, causing the cam plate to ride back down to its detent position. Cornering or deceleration during a transmission shift will cause a torque reversal of this type. The differential unit returns to its open diff function.

 

The self-energizing process would not occur if it were not for the action of one of the left clutch discs. This energizing disc provides the holding force of the ramping action to occur. It is the only disc which is splined to the cam plate itself. The other splined discs fit on the cam side gear.

 

If the rotating speed of the ring gear and differential case assembly is high enough, the latching bracket will pivot due to centrifugal force. This will move the flyweights so that no locking is permitted. During vehicle driving, this happens at approximately 32 km/h (20 mph) and continues at faster speeds.

 

When comparing the effectiveness of the locking differential, in terms of percent-of-grade capability to open and limited-slip units, the locking differential has nearly 3 times the potential of the limited-slip unit under the same conditions

 

 

I hear you, but thats not a locker..!! That style is called a Gov-Lock and they are the crappiest so-called locking devices I've ever seen. I understand GM calls it a Locker but its not, I would rather have a True-Trac or an Auburn limited slip than have that unit.

 

Look up Detroit Locker and see how the exploded view looks in comparison to that Gov-Lock and it will make more sense.

 

Rob

 

 

 

What ever, opinions vary