First I've been lurking around this forum for about a year and learning a lot and enjoying reading the posts.

Ok hear is my question. About 3 months ago I was starting my trip home from work in the rain and every now and then when I pull out into traffic in the rain the rear end starts to spin and doesn't quit when I let off the throttle. So sometimes when I need to pull out into traffic I will put it into Auto 4 wheel drive. I got distracted and forgot to put it back into 2 Hi and going thru a drive thru that was taking WAAAY to long I gassed it too much and the rear broke loose and I heard this loud pop from the rear axle. I got out of the throttle and went thru the drive thru and then went across the street and test drove the truck back and forth and in circles and everything seemed ok. Well today I was running some errands in the rain and pulled out into on coming traffic in 2 Hi and the rear end started to spin so I let up on the throttle and then gave it more gas and it started to spin again so pulled back into the parking lot and made a tight left turn to turn around and the left rear wheel started to chatter really bad. I stopped and drove forward and back and every thing was fine then turned hard left again and it did it again so then I turned hard right and all was fine. I turned some more circles and the chattering went away. I looked it up in my Helms shop manuals and it said to change the fluid and check the clutches. I something broke? Anyone have any ideas? I have 46,000 mi of mostly highway driving and no racing.
I hope to pull the cover tomorrow or thurs latest and look around as I was planning on changing all the drivetrain fluids this time home. Any info from you guys will be appreciated.

 

Sounds like the rear end is going out, thats how mine sounded when it first started going out. I would definately get it looked at if possible.

 

Thanks for the reply nightmarechevy. I pulled the cover today and didn't see any damage or metal on the magnet or in the oil. How do you tell which size rear ir has? I looked in the manual but didn't see how to measure to see if it is an 8.6 or 9.5. The RPO says GT4 3.73 and G80. I guess I'll put it back together and drive it around and see how it runs. Thanks for the help.

 

That is good, I'm glad to hear it wasn't the same thing as mine. It was totally torn up under that diff cover. $1700 later here I am with 4.10s, a locker, and everything else they had to fix . On the gear size ?, you can check your glove box for the codes and it will tell you what size gears you have. I will try to get the codes and post them for you.

 

G80 = Locking rear differential
2.73 = GU2
3.08 = GU4
3.42 = GU6
3.73 = GT4, GQ1
4.10 = GT5

I believe these are correct.

 

Thanks I have the RPO sheet with the option codes it just tells me GT4-Rear Axle-3.73 Ratio and G80-Locking Differential-Rear Axle it has C7H-6,400 Lb GVW But that doesn't say the size. The reason I'm asking is the amount of lub is different between the two. I guess I'll stick my nose back in the book. Putting back on the cover now.

 

It might just be that your G80 is starting to go out, I hear this happens fairly often. I didn't ave the G80 from the factory so I'm not sure how to help you out. If it is still under warranty I would take it to the dealer.

 

Well I'm passed the 36,000mi mark so I doubt that warrenty will cover it if it is going out. I still have to go get the tail gate straps changed I'll ask them then. Thanks for the help.

 

Just got my tail gate straps yesterday . Good luck with it, hope nothing is really wrong.

 

Ok Put everything back together and decided to look over the other fluids and air pressure. Well the left rear tire had less than 20 lbs air pressure. I wonder if that could have caused the chattering when turning full stop left? I aired it up and drove around and made full stop left and right turns and didn't get an chattering. I'll check it some more on the way to happy hour