Couple of questions about 4WD and G80

[Austin83]

I never paid any attention to or attempted to understand the G80 system until I started to look at buying a ZR2. I understand the premise behind how G80 works with one tire on dry pavement and one on ice, but what happens in 4HI when all four tires are trying to get traction on an equal slick surface such as ice? I normally test my 4WD out every year by attempting to accelerate from a stop on ice both in 2WD and 4WD to make sure everything is working properly and everything has the proper traction in 4WD. I always make sure all four wheels are on ice. Is this a safe way to test the 4WD system? I can't say that I've ever tested the G80 by just putting one wheel on dry pavement.

 

Next question, I'm going to look at buying a 2002 S10 ZR2 this week. How can I safely test the 4WD out on dry pavement before purchasing? I know you can lightly make a turn and feel the front end grabbing as you turn, but doing that has always made me cringe. Any advice is appreciated.

[gmtech4]

you can find a dirt road and pin it in 4hi ,,,,,doing that to 4lo is alittle aggressive ,as long as it shifts to 4lo its most likely fine

 

more advise is S10 are awful for fixing anything on them ,they are REALLY REALLY tight lol imo

 

good luck

[mescalero]

The rear end will react the same no matter if the the tranny is feeding power to 4hi or 4lo. The G80 diff is activated by centrifugal force. As long as one axle is spinning at least 100 rpm the lock engages. This works in reversal as well. Comes in handy going uphill in snow, wet clay, or similar surfaces.

[mescalero]

One other point. Standard GM issue 4lo cannot maintain g-force created at speed over 45mph without caving. 4hi will pull you through like a champ, tho!

[Austin83]

Great thanks guys, so the back two wheels would have equal amounts of power and wheel spin if both of them are on a solid sheet of ice?

[02suburbanZ71]

Make sure to change the fluid. It will make a difference when engaging. Im on #2 and and replaced bearings on the 2nd one. It unlocks over 25 mph which is good and bad.

Yes both do 50/50 because it is a locker

[Austin83]

Alright, found a deserted paved road on a hill with some wet grass on the edge of the ditch. I placed the right wheels on the wet grass and the left wheels on the pavement. After giving it enough gas to make the 100 rpm difference I felt a slight thud in the rear and the left tire chirped and the truck took off. I tried it a few times, and I didn't try to abuse it or accelerate too hard. I guess that is the normal operation for the G80?

[8.1HD/ALLISON]

Thats how they work. Normal operation.

 

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[txab]

 

 

 

 

 

[txab]

another one

 

[mescalero]

Here's something to keep in mind. Z71's were made (for some reason) in two gear ratios for a G80 type LSD. 3.73 and 3.42. If you are going to be pulling HEAVY loads (i.e. RVs, livestock, etc) up the steep and slick, the 3.73 is the ticket. If you're 4wheelin' for outstanding times...3.42 is for you. Remember though, if you switch from one to the other you will have to sync the tranny and engine to the new rear end whichever way you go. Look in your glove box for a label with the code: GT4 = 3.73 and GU6 = 3.42.

 

Enjoy!