Berend_Smit

Have Suburbans from 1981 to 1991 2500 4x4 Diff-lock standard?
Thanks

ZX1100F1

Not standard, look for option code G80 on the glove box options placard.

hquick

Yeah...the G80 'Govlock' is pretty common...also known as the 'Govbomb' as they have a tendancy to 'explode'

ZX1100F1

The old (1970 to mid 80's) GM Govlock rear-ends and thenewer Eaton G80 Locking Rear Differential are not the same units.

hquick

Can you please explain the diff(erence) ZX?

ZX1100F1

The marketing term "Gov-Lock” was originally introduced by GM in 1973 when the first "locking rear differentials” were introduced as a replacement for the dangerous positraction units, the Gov-Lock rear-ends were essentially a cross between a limited-slip and true locking rear differential utilizing clutches and plates that transferred torque to the rear wheels, the Gov-Locks were built by various manufacturers (none by Eaton) these differentials were notorious for failing (exploding), the Gov-lock rear ends were discontinued In the mid 80's due to their high failure rates.


GM then got with Eaton to develop a high quality mechanical auto-locking differential that is heavy-duty, GM dropped the use of the marketing name "Gov-Lock” and the RPO code "G80” was adopted as the new marketing name.


The Eaton locker does use clutches but only as part of the cam unit that engages the locking feature, the clutches do not transmit engine torque and for this reason the Eaton rear-ends do not fail and "explode” in the way the old GM Gov-Locks would.

The G80 is available in all GM light duty truck axles including the 8.6”, 9.5” and even the 10.5” axle which is used behind the 650ft/lb of torque Duramax engine.
Due to the nature in which trucks are used (and sometimes abused) the Eaton G80 units are not infallible but the failure rate is now very minimal in comparison.

The Eaton G80 is intended to benefit the average truck buyer by transmitting torque to both rear tires when wheel slippage occurs, this feature works well in instances where one tire is off the ground or on ice or other slippery surfaces but it is not always optimum for off road (4X4ing) use, many off-roaders prefer to have full manual control of their differential locking mechanism and to engage it prior to entering an area of poor traction and for these folks the G80 is not suitable.

Over the years the terms "Positraction”, "Limited-slip”, "Locking”, "Gov-lock” have been thrown around in a generic way of referring to any and all types of traction enhancing differentials.

hquick

I'm sorry ZX...I think you may be misinformed.
The G80 'gov bomb's' as they're affectionately known are pretty famous....or 'infamous' for grenading with any mild sort of abuse (ie....offroading) or power addition.
Here's mine....98 Suburban K1500 4x4...and I wouldn't say it was abused. Took off from an intersection...reasonably hard (but not enough to spin the tyres) because there was alot of traffic and came to a sudden holt with a loud BANG!.

Berend_Smit

So If I want to go offroading with a suburban the best is manual differential locks. Do you need to replace the whole axels than or can you just put another differential on it?

Thanks

hquick

I installed a Eaton 'Trutrac' in mine...as have many others.
No problems yet and I've never heard of anyone having any.
You only need to replace the centre/carrier not the axles.

ZX1100F1

It's unfortunate that you lost a rear-end on your 10-year-old Suburban but looking at the black sludge makes me wonder how often the unit was serviced or even the lube level checked. I’ve owned at least a dozen GM trucks and SUV’s over the years with a G80, I pull heavy trailers and have not once lost a rear end; not that it doesn’t happen; it just isn’t as big a problem as you’re making it out especially since GM switched to synthetic gear lube in 2000.

The current G80 locker is covered under the 5 year/100,000 mile powertrain warranty.