1500 HD Crew Cab

dwskas · January 14, 2004

Just wondering if anybody out there has a 2002 Silverado 1500 HD. Any problems or anything I should know about the truck. The only problem I have been experiencing is my locking diff. It seems when one wheel is slipping the other won't grab. I brought it in for a check and they told me it works fine and I still disagree.

Shotgun · January 14, 2004

I own a 2001 and no problems to this point and my diff locks when it is supposed to.

AlanTDickey · January 14, 2004

What's the easieist / most-reliable way, if any, to confirm that my lockers are locking properly???

gave20 · January 14, 2004

What's the easieist / most-reliable way, if any, to confirm that my lockers are locking properly???

jack the back end up and spin the wheels both should spin, or find some gravel and burn out; if you leave two disturbed areas it works

carguru · January 14, 2004

If you drive across a ditch (shallow) at an angle in 2wd mode at slow speed, you should be able to tell if it were working. If it is not too muddy, it should be able to pull you out with just the rear wheels.

AlanTDickey · January 14, 2004

Thanks gave20. I'll probably try the double-burn-out option at a construction site near my home.

Carguru: I'm not entirely sure what you mean. Are you saying try to get one tire completely off the ground and see if the other has traction?

Shotgun · January 14, 2004

I leave two marks on the pavement,thats how I know mine is working.You can always just get in the grass and nail it.

JayMan · January 15, 2004

What's the easieist / most-reliable way, if any, to confirm that my lockers are locking properly???

This will be a long post but hopefully it explains why your G80 is not working.

The G80 GovLok is speed sensitive. That is, it reacts to the difference in speed between the two rear wheels, not in the amount of input torque you apply. This is quite different than a regular "posi" or Limited Slip.

Although the G80 has clutch plates like a limited slip, there is no preload spring between the left and right packs to bias the packs for engagement. Instead, there is a flyweight/governor assembly that reacts to a difference in wheel speed between the two rear wheels, catching a pawl that forces the clutch plates together. This "locks" the rear end and is designed to work only at speeds under 20 MPH. At highway speeds, the flyweight/governor is designed to NOT lock.

For more information, go straight to that horse's mouth:

http://www.traction.eaton.com/prod2.htm

You will find lots of good information, and you will also find the very contradictory maintenance information in Eaton's FAQ. More on that later.

Here is how I check mine:

On your cement or paved driveway, jack up one of the rear wheels and put a jack stand under it. Get in, start up, make sure the 4WD selector is in 2WD, put it in Drive, and GENTLY give it some gas.

If the G80 is working properly, a very light application of power should lock the clutch plates and the wheel on the cement/pavement should begin to drive the truck off the jackstand. The engagement should be SMOOTH no herky-jerky at all.

I don't like to do the "burnout" test as this is the G80's weak point. It's also nicknamed the "grenade 80." Well, it's your truck so do whatever.

If your G80 just lets the wheel in the air spin, or if it makes a clattering sound like a marble in an empty coffee can, time to investigate further.

First, how many miles on it? Second, have you ever serviced the rear end? If so, did you use the PROPER gear oil?

First point: if you have quite a few miles, drain the rear end. Then remove the rear sheet metal cover and inspect the magnets there. A fine fluffy stuff like metal filings or shavings are normal. If you find actual gear CHUNKS, there could be a problem with the flyweight/governor assembly inside the G80. This will require disassembly and repair, hopefully you still have warranty.

Second Point: if you have recently serviced the rear end, what gear oil did you use? There is VERY contradictory information regarding what sort of gear oil to use in that unit. If you read the Eaton FAQ, they recommend a regular 80W-90 plus additional friction modifier additive.

If you have serviced the rear end and, following the plastic tag near the fill plug, put in any 'ole synthetic 75W-90, the G80 will probably not work. I know from experience.

I have pails of commercial gear oil in my shop, all of it Mobil MobilLube SHC 75W-90 to keep the warranty in my Eaton HP-40 axles. This stuff is SUPER slippery. All commercial gear oil is.

By mistake, when I did my initial gear oil service in my truck at 600 miles, I put Exxon SGO 75W-90 in. We had an early snow and the rear end was slipping and chattering like crazy. I called Exxon to complain and they said to drain it out ASAP before the clutch plates became glazed.

I drained and refilled with 3 tubes of CRC Trans-X PosiTrac additive and the cheapest NAPA 80W-90 I could find. It wasn't that cold yet so I wasn't worried about running the 80W-90.

I drove around for a couple of weeks and as time went on, the G80 fully came back to life. After that, I drained and refilled with 1 tube of the CRC additive and Mobil 1 Gear Oil 75W-90 (It claims suitable for Limited Slip applications).

Haven't had problems with it since. I wouldn't count on the dealer to just tell you "works fine" as they like to get out of any warranty claim.

Try the jackstand test first. Let us know what happens, then we'll go from there. Sometimes just the drain/refill with the extra additive will bring it back to life.

GM GIMP · January 15, 2004

I have a 2002 1500HD 2wd and have had no problems at all. At about 8,000 mi. changed the gearset from a 3.73 to 4.10. The rearend was in excellent shape.

Used the gear oil from GM; expensive but it is the right stuff. Reprogrammed

with Hypertech for speedometer. BTW these rears are the 14 bolt with C-clip

axles. Always specify this if you need parts.

Mark

YZRider · January 16, 2004

I have an 03 1500HD 4X4 with the 4.10 locker. I just serviced my diff, so as to make sure everything is OK before I put the supercharger on, everything looked good. I used synthetic 75/90 Quaker State, it says it is suitable for all limited slip differentials, seems OK so far.