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G80 Locking diff. Question...

Frozen001

By Frozen001
in Ask A GM Technician

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Frozen001 Enthusiast

Frozen001

Posted
Posted

OK my 2500HD has the G80 Locking rear diff. and I have a question on proper operation.

 

We had our first snowfall of the year here, and I notices something I did not notice about my locker last year.

 

I am pulling up into a sloping driveway that has a thin layer of ice under the snow. Truck looses traction, I hear the G80 clunk, which to me always meant it locked the axles up. No last year it always clunked ounce remained. In this situation, it never seems to stay locked up. It clunked repeatedly and the tires would just spin and spin(Truck did not move forward... it actually slid down the driveway a bit). Now I was not outside the truck to say weather both wheels were spinning, I just know the the truck did not move forward. I had to lock it into 4wd to get up the drive way. To me it seems like the locker would only engage ounce and stay locked until the truck advanced some distance.

 

I am just concerned about the multiple clucks. It was almost like a chattering noise. I do not hear any odd noised our of the rear end when driving around.

 

Should I have it checked out??? Or is this how I should expect the G80 to work on a very slick surface like snow covered ice.

  • 1 month later...
Mark2500HD01 Enthusiast

Mark2500HD01

Posted
Posted
OK my 2500HD has the G80 Locking rear diff. and I have a question on proper operation.

 

We had our first snowfall of the year here, and I notices something I did not notice about my locker last year.

 

I am pulling up into a sloping driveway that has a thin layer of ice under the snow.  Truck looses traction, I hear the G80 clunk, which to me always meant it locked the axles up.  No last year it always clunked ounce remained.  In this situation, it never seems to stay locked up.  It clunked repeatedly and the tires would just spin and spin(Truck did not move forward... it actually slid down the driveway a bit).  Now I was not outside the truck to say weather both wheels were spinning, I just know the the truck did not move forward.  I had to lock it into 4wd to get up the drive way.  To me it seems like the locker would only engage ounce and stay locked until the truck advanced some distance.

 

I am just concerned about the multiple clucks.  It was almost like a chattering noise.  I do not hear any odd noised our of the rear end when driving around.

 

Should I have it checked out???  Or is this how I should expect the G80 to work on a very slick surface like snow covered ice.

 

 

 

 

Hey frozen, this is premierland from plowsite. I think it normal for it to do that, I think its just the locker trying to engauge. But im sure someone will let us know! Cheers

firerage101 Enthusiast

firerage101

Posted
Posted
OK my 2500HD has the G80 Locking rear diff. and I have a question on proper operation.

 

We had our first snowfall of the year here, and I notices something I did not notice about my locker last year.

 

I am pulling up into a sloping driveway that has a thin layer of ice under the snow.  Truck looses traction, I hear the G80 clunk, which to me always meant it locked the axles up.  No last year it always clunked ounce remained.  In this situation, it never seems to stay locked up.  It clunked repeatedly and the tires would just spin and spin(Truck did not move forward... it actually slid down the driveway a bit).  Now I was not outside the truck to say weather both wheels were spinning, I just know the the truck did not move forward.  I had to lock it into 4wd to get up the drive way.  To me it seems like the locker would only engage ounce and stay locked until the truck advanced some distance.

 

I am just concerned about the multiple clucks.  It was almost like a chattering noise.  I do not hear any odd noised our of the rear end when driving around.

 

Should I have it checked out???  Or is this how I should expect the G80 to work on a very slick surface like snow covered ice.

 

 

 

 

Hey frozen, this is premierland from plowsite. I think it normal for it to do that, I think its just the locker trying to engauge. But im sure someone will let us know! Cheers

 

 

 

 

 

You all beat me to the post i hope that someone does answer this as i had it happen a few days back, i woudl think it's normal operation though.

silverad03 Enthusiast

silverad03

Posted
Posted

I've had this type behavior happen in my Z71 too.

 

Disclaimer: I'm no expert on the G80...this is my understanding based upon what I've read around here from a variety of posts...somebody correct me if I am wrong....

 

The G80 locks the axles together whenever one wheel spins in excess of about 100 rpm faster than the other, up to 20 mph because at that speed the locker automatically disengages. The locker also disengages below 20 mph when both wheels are spinning at the same rate and the torque is about the same on both axles...

 

My guess is that when you tried to get going in 2wd, one wheel spun up and the locker did it's job and locked the axles together (which caused the clunk you know and love), but you probably didn't have sufficient traction under the other tire to get the truck moving either and that tire spun too and almost equalized the torque applied to each wheel, which caused the locker to disengage. But as soon as it disengaged one wheel began spinning faster and it locked up again...and repeat...

 

Basically, you didn't have enough traction under either tire to get the truck moving but you probably had just a wee bit better traction on one side so the G80 couldn't get you going even though the axles were locked together.

 

All this explanation to say...this sounds like normal operation and is all you can expect if the truck can't get any traction from either wheel...

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