Any g80 posi experts here?

[Nanotech Environmental]

Hi -

 

I have a G80 posi in my 2006 1500 4x4. It often locks up when not needed on dry pavement etc, usually when just about to go around a corner. Kinda annoying, not to mention it's hard on rear tires.

Sometimes when it releases, it makes a noticeably audible bang.

 

Anyone know what causes this? A visual inspection doesn't indicate anything obviously out of order to my untrained eye....... I've tried oil changes etc., to no avail.

 

Thanks in advance.

 

 

[RyanbabZ71]

1st, its not a posi

 

How is the fluid level?

[02suburbanZ71]

1/2 ton g80s are known to be a problem. Check/ change with gm fluid to proper capacity, if lockup continues to occur take to transmission shop for diagnosis

[02suburbanZ71]

Were there any shavings on the diff cover magnet? Did you add posi additive to the pumpkin??

[Colossus]

did you change the fluid recently? If so what did you use?

[KMGZ400]

How often does it lock up? Mine used to do it occasionally maybe 1 once a month or every 2 months.. Always did. I would just put it in reverse or floor it and it would unlock

[Nanotech Environmental]

How often does it lock up? Mine used to do it occasionally maybe 1 once a month or every 2 months.. Always did. I would just put it in reverse or floor it and it would unlock

It locks up on a daily basis, usually several times a day. I used a non additive oil equivalent to the stock oil. There were no appreciable shavings or particles on the magnet, at least nothing that wouldn't be there from normal wear. Fluid level was full before and after the change.

 

I suspect there must be a mechanical issue with the unit. Just wondering where to start looking..... I won't take it to a shop to get it fixed, as I do all my own mechanical work.

[02suburbanZ71]

Yeah i think that your g80 might be going south

[00Silverado4x4]

Do you have any experience with differentials? If not you may have to take it somewhere for diagnosis & repair.

[02suburbanZ71]

Do you have any experience with differentials? If not you may have to take it somewhere for diagnosis & repair.

X2

[Colossus]

Wouldn't hurt to drain and put in actual GM fluid made for that thing. If that doesn't solve it then you can expect a $1400+ repair/replacement.

[Z45]

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.

 

The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials (Posi-Traction) 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.

 

Note - After replacing the lube, drive the vehicle in tight figure 8's several times to work the new fluid in the G80 clutch pac.

 

PS - The GM fluid is usually in the axle when these problems come up, recommend not using it.

[Nanotech Environmental]

Do you have any experience with differentials? If not you may have to take it somewhere for diagnosis & repair.

I'm not concerned about that. I've always had good abilities with mechanical things. This thing is less complicated than any engine I've rebuilt, or transmission I've worked on. I'm just trying to get myself educated on the unit first, as often there are tricks etc. regarding dissassembly, assembly etc.

[Duelin]

No tricks just experience and knowledge.

[Nanotech Environmental]

No tricks just experience and knowledge.

Care to elaborate?