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I'm planning on using 6L80 or 6L90 in my Jeep, I want the
6 speed to help make up for the complete lack of any
aerodynamics at all.. On paper my engine rpm's just will
never be right with a 3 or 4 speed.
The engine will likely have a mild tune to optimize it for my use
(Offload and getting to the offload, hunting and such.)
and for matching it to my chassis.
My question is,, whats likely to go wrong with this series trans?
My Jeep weighs about 3800 Running a Dana 44 and a dana 30
front so I have no illusions about what will happen if I try to get
too crazy with power in it.
I'm hoping that before install if there are any obvious
weaknesses I can have that taken care of before I install it.
I'm planning on buying a full drop out if not the whole truck..
I need cats and I want to try and keep it as simple as I can
by keeping the originally mated components, ecu etc together..
Just to confirm, you plan to take the engine and 6L80E out of a donor truck and of course the ECM/TCM?
Perhaps someone here has the experience to tell you what else is needed. For example, is the Body-Control-Module also needed and how do you clear all the resulting codes?
This is by no means a guarantee, but if you get a low miles unit that hasn’t been used primarily for towing I doubt you’ll run into many issues. The 4-5-6 clutches can fail, although there seems to be an inherent issue with factory apply piston. The 3-5-reverse clutches tend to fail occasionally as well. If you have a unit in good condition I would not expect it need much for a mild power setup, especially in a Jeep, as these transmissions were designed for 5,000+lb vehicles. I’d still advise a good TCM tune. This will likely result in a little more stress on the remainder of the driveline though.
Having said that I’d make sure you set your pinion angle as close in line with driveshaft angle as possible and run a CV style shaft- I can’t tell you how many pinion bearing failures I’ve come across in D44 and D30s. These will almost certainly be your weak link, not the 6L80.
Yea I'm sourcing as late model as possible without direct injection, I'm also looking for a 2wd unit as I am using a Novak adapter and a NP231/241 hybrid case, slip yoke eliminator and double cardon drive shafts, I'm putting the VSS for the engine in the adapter between the transmission and transfer case so I don't have to fight the stupid tuning GM does when your in low range.. I'm lucky my front diff is a high pinion D30 with real reverse rotation gears so front driveline has very little angle so under power its pretty well behaved. Also the guts of both axles are ARB diffs + Chromolly axles.. 250K miles so far.. But can't take the 100 hp 12MPG 4 banger any more..
Oh and thanks for the response, its kinda what I thought,, My current assumption was that for my use,, it oughta hold up fine, The obvious fuse is the axles,, But I'm more of an explorer I don't mud or rock crawl..
If you go to the Advance Adapters site it specifically says the 6l80 is not a good choice for Jeep transplants, but I suppose it could be done. Also I meant CV shafts, not double cardan. For reference I pulled my 5.3/6l80 combo out yesterday, it’s quite long.
Good luck though if you can pull it off!! My 3-4-5/R drum is cracked I’m almost positive, which is the main reason it’s out now.
Believe it or not,, my AX5 5-speed is almost the same length (within about a 1/2 inch ) of a 6l80... Its fun trying to decide who's right, Novak or Advanced adapters.. Novak answers questions better than advanced from my experience.. I know its a no-go in a CJ5 for sure,, Lots of fun trying to find real world folks that did some of it.
I've tried both CV and Double cartoon and the Doubles have held up better,, With a Ultra short SYE on my transfer case, I actually end up with a longer driveline in the rear than I have now (If the math is right.. ) The CV's do run smooth..
Hey! Just getting back on my build. The novak motor mounts I installed as to their specs, was too close to the firewall. I cut them out and installed daves customs mounts. They won't lie flat and ride a little lower than the novaks. They alos needed to come forward an inch from the instructions. But, my headers fit now! To use the 6L80e you will need at least a one inch body lift. (I'm not big on body lifts, but it is needed.) As for the computer issue, mine has the E38 ecm and the internal tcm. I used speartech for my ecm and harness. I removed my tcm and sent it to them to get flashed. I have no bcm on mine. I'll post some photos of where I'm at now.
6L*0E Transmissions Whats wrong Whats right.. 
Yea I'm sourcing as late model as possible without direct injection, I'm also looking for a 2wd unit as I am using a Novak adapter and a NP231/241 hybrid case, slip yoke eliminator and double cardon drive shafts, I'm putting the VSS for the engine in the adapter between the transmission and transfer case so I don't have to fight the stupid tuning GM does when your in low range.. I'm lucky my front diff is a high pinion D30 with real reverse rotation gears so front driveline has very little angle so under power its pretty well behaved. Also the guts of both axles are ARB diffs + Chromolly axles.. 250K miles so far.. 
But can't take the 100 hp 12MPG 4 banger any more.. 
