I will put this disclaimer out now, this post is meant for a good hearted and genuine discussion so PLEASE don't take it any other way. I'm not attempting to say anyone is wrong or their ideas/comments are stupid, I want to spark a genuine discussion here.
I've put together a quick "pros and cons" list (feel free to add any I may have missed or didn't think of). I never would've thought in my wildest dreams I'd even be in this situation. My intention here is to have a discussion where people who are smarter than I am about this issue can possibly help with putting this ship on the best path so to speak.
The truck will weight approximately 5500lb in race trim, maybe less. My goal is to have a "reliable" (I know) 5.90 truck that my father and I can also take on race week type events (Midwest/Rocky Mountain/Power Tour etc). From what I can tell, the 4R seems to be a great "hybrid" of a TH400 and something like an Allison. It is a non-synchronized clutch to clutch shift will full line pressure control. If I wanted a pure 1/8mi drag truck I would lean toward a TH400 all day long but that isn't going to be it's only use.
*****Allison*****
Pros:
1) Decently reliable when built properly
2) Good aftermarket support
3) Ratios better suited to the the powerband of my triples over a TH400
4) Strongest internal hard parts (shafts etc)
Cons:
1) Still not bullet proof, killing C3s in short order when asking them to make consistent 5.90 passes with weight
2) TCM, even with the best tuning, still sometimes does what it wants (AL5 seems to be far better than A40/A50) leading to inconsistency
*****TH400*****
Pros:
1) Most reliable/proven drag trans
2) Most aftermarket support on the racing side
3) Infinite ratios for 1st and 2nd gear to dial in those two gears
Cons:
1) Limited to 1/8mi due to a 1:1 3rd gear ratio with lockup, meaning that a 30" tire on 3.42 will be limited to around 130mph and would cross the stripe at ~5000rpm, 32" tire is around 140mph at ~5027rpm. My triple setup will not make efficient power at that RPM
2) Expensive to build for the power and lockup with the weight of the truck
3) Not the best suited for say a race week type event where the truck will need to drive to each event
4) Would need an exotic solution (gear vendors?) to run 1/4mi
*****47/48*****
Pros:
1) Decently reliable when built properly
2) Good aftermarket support
3) Gone faster than I plan on
4) Ratios better suited to the the powerband of my triples over a TH400
5) Offers great tuning support when controlled over a PCS-TCM2800 plus full CAN data (if I didn't go FMVB/air shifter)
Cons:
1) Still not bullet proof
2) Has bands that can be finicky at big power/fast ETs
3) Duraflites (from what I've read) have had converter issues in the past but seem to be much better now
*****4R100*****
Pros:
1) Decently reliable when built properly
2) decent aftermarket support
3) Gone faster than I plan on
4) Ratios better suited to the the powerband of my triples over a TH400 (same OD at 0.71 as a 5spd Allison)
5) Offers great tuning support when controlled over a PCS-TCM2800 plus full CAN data
Cons:
1) Still not bullet proof, Chris @ TSD said they're breaking intermediate shafts but are working on a solution that should be out soon
2) Requires good tuning to be consistent (TSD seems to have this down)
