my avalanche is putting down some large hp numbers to the fact ive toasted 3 4l60e trannys. Im doing a 4l80e conversion but still have a question. on our trucks the transfer case still spins even in two wheel drive un till the front actuator on the front diff engauges the pin to lock the front diff. so even in two wheel drive the front shaft still spins. ive been looking for a performance upgrade as far as transfer cases go and can only find stuff for jeeps and dodge. does anyone have any suggestions? how can i upgrade the transfer case so that its not the next thing ill be replacing. kinda like to do it at the same time i put the 4l80e raptor in all at once. i posted this in FI because my truck is procharged and running high hp and trq levels and im hopeing some other FI trucks have info on this.

 

To be honest I havent heard of one of these tcases ever breaking...but even so, the ones from the HD trucks are a bit stouter. Depending if you have a manual or auto tcase the bigger one will be the np263hd or something else...

 

The transfer cases are different from the HD transfer cases as he is AWD. Basically AWD has a differential in it to divide the power as needed to front and rear and the 4X4 is locked 50/50. Not good for street performance. Unless it's a straight line.

Edit: Nevermind for some reason I thought he had a Denali. Must be reading too many threads.

 

If you don't mind me asking what broke or failed in your 4l60e setups?

I'm not to sure on the newer t-cases, but on most olded ones you will have problems when fluid gets dirty or low causing the chain that operates the front driveshaft to wear out faster. Keeping fluid toped off and clean is the biggest improvement on an older case....and maybe replacing the internal chain drive since most will have a ton of miles and who knows what kind of redneck owned it before.

 

i have owned the truck since new and i do not have awd. i have a NP246 which is selectable auto, 2h,4h, and 4low. im doing a 4l80e conversion so i have the shafts in the tranny converted to bolt up to the NP246 as i aslo have the correct front and rear shafts to account for the longer 4l80e trans. and a plug in harnes. I just have to write a new file to the cpu to work with the 4l80e. i would have gone to the hd transfer case as well but this conversion already changed the shafts in the 4l80e to bolt up to my current config. so i was just wondering if anyone has upgraded anything besides the pump mod in the NP246 to strengthen them. as far as street performance pulling 12's in a 7000lb avalanche sounds pretty impressive to me. just want to get the 4l80e in and then find out the transfer case is the next weak link now and break it.

 

Ask stock48 how to break one... He is the only person I know of doing it, and he was making far more power than you are or ever will without a forged motor. IIRC, it was launching in 4hi and switching to 2hi after the second gear shift that toasted it, now he probably just makes his entire 9.xx pass in 4hi.

 

thats funny that you posted that cause thats how i launch..lol...so i guess im going to be ok with using the NP246 and just fresh it and do the pump mod. thanks.

 

as far as 4l60 failures the stock unit blew out 3-4 clutch plates, the second one blew out 1-2nd clutch packs. this one i put a trans go kit, all billet servos and a hardened plate. dont know ex wat blew yet gonna pull it monday or tue to find out. it was overheating and not shifting right i think 1-2nd went however i pulled into a parking lot called a tow flatbed and 1hr later i went to start it and it was totaly locked up was going to move it on to the flat bed but no luck had to drag it up. no more 4l60e's for me im done

 

I see that 27 spline output shaft on your 4L80e as the next weak link lol.

 

Wise choice to swap to the 80e .


This thread brings up the question, should we push 2 hi after we launch and get moving?

I do all the time with no probs, but if it will cause a prob i wont.

I thought running the 4x4 at 110+ mph would be bad haha.