So, bumping the ol' build thread back up with a question or the opinion of others.
I'm working the driveline on the Jeep and trying to button up what's left. That said, the NV3550 5 speed is on the bench waiting on the gent who bought it to come get it this weekend. I'm auto swapping.
What I need: An auto transmission that will bolts to my 4.0 (without expensive adapters) that also has a 23 spline output. I am not 100% worried about the crank sensor as I made a template to know where to drill the bellhousing if need be.
Options I've found:
TF727 - add says "recently rebuilt by Bowie Trans svc in MD using a cummins rebuild set and a 4.3 ratio low/reverse apply arm. A new low stall Dacco converter comes with. I will toss in a flex plate for those wanting to put it behind a TJ/YJ 4.0. I drilled the case for a vent and plugged the FP vent. Never been used. I have NEW cables/brackets for use on a TJ. Cooler also included. Advance adapters CPS relocation kit included." He's asking $650.
TF999/A999 - I've seen a few ranging $150-$250, including one that is $200 and claims to be rebuilt. I do know the TF727 and TF999 are very close to the same thing, with the TF727 being slightly stronger. This route, I would need to find all the other swap parts. Flex plate could be used from a TJ/XJ.
My worry with both the TF727/999 stems from the following I read on pirate4x4:
"TF727 Sprag failure results from shock loading the drivetrain in first or second gear, such as attempting to climb a slippery obstacle where a lot of throttle is used, and not quite making it. If you don't get off the throttle fast enough and the tires find traction when sliding back down, this is enough too pop the sprag. torque flights are well known for this problem, and to a lesser degree, pretty much any simpson design auto can experience this failure. In almost all situations, breaking the sprag ruins the case, and the only way to get the vehicle to move to manually shift the trans into L. Shifting into low applies the low/reverse band or clutch (depends on the trans) and this gives something for the low/reverse planet to hold against.
I broke my old TF727 3 times like that, but did not know that if the trans is in D and you start off from a dead stop, all of the engine torque is pushing on that sprag. Manually selecting L engages the low/reverse clutch and relieves that stress."
Should I be worried about this? I know 727's are strong, but this kind of worries me. This brings me to the final option I've considered.
AW4 - Found stock in XJ's and they're stong as all get up. Can be had $100-$200. I've read a lot of guys running these in buggies with great success. Downfall to them is their length (about 2" longer then a 727/999) and they build a lot of heat. A large cooler is needed to keep them happy. Also, they're electronically controlled. To go this route, I'd use shifters from here:
http://radesignsproducts.com/Home.php. These basically use a set of solenoids to allow you to manually shift all gears, which is nice. I'd also need a stock XJ shifter cable, but that's not a big deal. AW4 has provisions to use the stoc crank sensor. The flex plate could be sourced from a XJ/TJ stock.
Whatever route I go, the 4.0 is staying. Also, I'd want the 23 spline output to match the transfer case I just scored.
I am kinda leaning toward the AW4. Cheap, easy to find, and ultimately I think it may be stronger based on the sprag on 727's. Really just wanted to see what others thought considering the info. Also, are there any other options I'm missing?