This will be the 4th transmission going into my 04 Avalanche 1500 with the 4l60e. If my wife didnt love it so much I would have sold this hunk of crap years ago. It had the original, 2 replacements and 1 rebuild so far, and it has failed again. The latest failure was an actual oem transmission from GM. It had a 3 year warranty and the rear planetary failed 3 months after warranty expired. I will be rebuilding this one with upgraded parts and selling it! The more I research the 4l60e, the more I realize they are far too weak to be under this big of a vehicle, and have many major flaws.

Going on the 3rd transmission now (hasn't even hit 150,000 miles yet). First time it was replaced around 2010 by previous owner. Then when i bought it in 2014, the clutch packs and servos were going bad so i had it rebuilt. Now its august 2016 and it totally crapped out again. So going to GM and getting another oem replacement with a warranty so at least ill be covered when it goes out probably like 2 years from now. The 4l60e transmission was never designed to be put behind a heavy vehicle like the avalanche, especially if you plan on towing anything or putting bigger tires and things on. Its very weak!

so now, other than minor lights and door issues, I have had to problems driving this truck.. I came home from work, pulled in my driveway, put it in reverse, to straighten it up, and it would not go into reverse, it was like it was in neutral. I tried it a couple of times , nothing. so when I was on the phone calling for help to push the vehicle back to get out my car to drive to work.. it decided to go into reverse, as I continued to try it. so I drove my car to work the next day, had my ex get my truck to take to the shop to check it out, it worked fine for him, in my yard, as he got about 1/4 mile from my home, it stopped, trans ripped apart, as he put it.. lol.. weird thing, is that he could put it in reverse at that time, but nothing else..so now it is at the shop, probably in the process of getting another transmission put in it. my point being, I have only had this thing since Feb 2013. it looks really good, was running really good, all the interior (leather) was good, no tears or anything, just a little wear. body was good, just a small spot on the back bumper and the tires needed replacing , and 1 owner.. it is a 2004 but I was highly advised by people who Knew what they were doing, that this was a great buy.. so much of a great buy, look at how much this is already costing me... bad thing, there was nothing indicating that the transmission as failing..

My 2004 Avalanche experienced a complete transmission failure while cruising at highway speed. The failure required a $1700 rebuild since gears were damaged (I checked the parts and saw that there was considerable wear in the sun shell and gears). The mechanic that did the work took the time to check why it failed at only 73,000 miles...turns out that GM had installed the incorrect/mismatched valve body gaskets, leading to overheating and eventual failure. I contacted GM about this premature failure and the incorrect valve body gaskets, and they refused to help.

I've seen so many similar trans issues w/the Ava, I suggest that we all file complaints with NTSB (odi.nhtsa.dot.gov/VehicleComplaint/index.xhtml) so they can investigate why there are so many Ava transmission issues.

This Avalanche is my BABY. I have ALWAYS changed the oil & serviced it every 3,000 miles. I keep it spotless. Coming home last night, the speedometer registered 50 mph while stopped, waiting for the green light. I thought...a sensor. A couple miles up the road, it registered 110 mph, and the transmission started slipping badly. I barely made it home. The local dealership told me it would cost $3000 to replace, but a NAPA certified mechanic friend of mine quoted $2000. This happened right out of the blue, no warning. What's the deal GM ??? You get a vehicle paid for, and it flies all to hell. I should've traded for the F150 I was looking at a couple months ago. At least they will stand behind their trucks. Last GM truck I will ever own.