What did you do to your NBS GMT800 Tahoe/Yukon Today?

[strutaeng]

Performabuilt Level 3 4L60 rated for 900 HP but with AWD and the weight combined with a blower and my right foot it’s been a problem. I’m nowhere near that kind of power. After the first 2 times I destroyed it they figured out I was screwing myself because I used RTV on the pan gasket both times I changed the fluid/ filter which blocked the servo passages so they weren’t releasing which caused it to shift REALLY firm, as in the whole truck would shake. The second time it twisted the output shaft in two, that was on a 1-2 shift. I thought we had it figured out and Ryan @ Performabuilt talked me out of upgrading to their Black Edition which they claim has never been broke. The parts were back ordered anyway. He rebuilt it that time for free even though it was a year out of warranty. This time I’m not sure what happened. I did do a short AWD burnout once or twice prior which is hard to do with the NVG149 transfer case it has. I actually haven’t even diagnosed it yet- maybe it’s not the trans but it seemed like it was; on a hard 3-2 downshift I heard something break and I drove a few more blocks to get off the expressway and when I pulled into a parking lot I had to manually downshift into first and then it just locked up and the engine died. It runs in neutral but as soon as I put it into gear it wants to die. I have to work on it in my driveway and I have been busy with health issues. I will figure it out and fix it. I have way too much time and money invested in this truck to give up although it crossed my mind. If it’s the transmission I have to ship it to the east coast from the west coast but I have done it twice already. I still have the shipping box.

Have you ever considered swapping to a 4L80e?

A STOCK 4L80e transmission is pretty dang tough in a 3/4 ton+ work truck or van towing and getting abused 6-7 days a week. In a light 1500 chassis, that transmission literally laughs at you when you push the metal-to-the-metal. Not joking either.

I know the 4L60e, 4L65/70, etc. al. can and do get built to handle high HP and abuse, but that's usually on lighter vehicles like cars, albeit at a pretty dang hefty price because literally everything internally gets replaced, then you still manage to break the next weak link. SMH.

My logic has always been, "I simply can't afford a 4L60e". Just a thought...

I hope things get sorted out, regardless. BTW praying for your health Brother.

 

[Rocket Man]

Have you ever considered swapping to a 4L80e?

A STOCK 4L80e transmission is pretty dang tough in a 3/4 ton+ work truck or van towing and getting abused 6-7 days a week. In a light 1500 chassis, that transmission literally laughs at you when you push the metal-to-the-metal. Not joking either.

I know the 4L60e, 4L65/70, etc. al. can and do get built to handle high HP and abuse, but that's usually on lighter vehicles like cars, albeit at a pretty dang hefty price because literally everything internally gets replaced, then you still manage to break the next weak link. SMH.

My logic has always been, "I simply can't afford a 4L60e". Just a thought...

I hope things get sorted out, regardless. BTW praying for your health Brother.

Yeah I considered it but with the NVG149 transfer case it’s a real challenge making it work. There was a guy on PerformanceTrucks.net who designed and had a machine shop build custom output shafts so they would work together but they’re impossible to find now at any price. If one pops up they’re super spendy; they started at $400 years ago but now guys can pretty much name their price. Plus the custom crossmember, custom tune etc and it’s too much headache for me. Performabuilt builds some of the upgraded parts for the 4l60 in-house on a CNC machine and they say the Black Edition can’t be broken so I’ll probably go that route if the parts are available this time. If it’s the trans which it probably is.

 

[strutaeng]

Yeah I considered it but with the NVG149 transfer case it’s a real challenge making it work. There was a guy on PerformanceTrucks.net who designed and had a machine shop build custom output shafts so they would work together but they’re impossible to find now at any price. If one pops up they’re super spendy; they started at $400 years ago but now guys can pretty much name their price. Plus the custom crossmember, custom tune etc and it’s too much headache for me. Performabuilt builds some of the upgraded parts for the 4l60 in-house on a CNC machine and they say the Black Edition can’t be broken so I’ll probably go that route if the parts are available this time. If it’s the trans which it probably is.

Ah, ok. Gotcha. I think I saw that thread on PT.net. I bet with both TC input shafts in your hand, a machine shop could duplicate things. Or swap to a NP246 or something else?

I did a 4L80e conversion on my 99 Silverado, but it's a 2wd, so pretty easy. Not even cutting the driveshaft. I did cut/rewelded my transmission cross member though. I got a local guy to reflash my ECU, but I've since got myself HP Tuners, so I figured how to do the "segment swap", which is pretty straightforward.

 

[Rocket Man]

Ah, ok. Gotcha. I think I saw that thread on PT.net. I bet with both TC input shafts in your hand, a machine shop could duplicate things. Or swap to a NP246 or something else?

I did a 4L80e conversion on my 99 Silverado, but it's a 2wd, so pretty easy. Not even cutting the driveshaft. I did cut/rewelded my transmission cross member though. I got a local guy to reflash my ECU, but I've since got myself HP Tuners, so I figured how to do the "segment swap", which is pretty straightforward.

Yeah I just want to get it back on the road and then I’ll drive it easy. I’m getting too old to be messing around with it too much. Maybe if I was 20-30 years younger.