[Half-Inch Stud]

I've been in hot-pursuit of thic combo. Took the 4R70W out of my spare Lincoln, tore it down, analyzed it. Findings:

1. All Frictions & Steels are Borg-Warner (some packs have smooth, some packs have grooved), all had excellent wear patterns and are fit for re-use EXCEPT; the Intermediate Clutch Frictions (4 discs) had wore teeth (I've seen this on only a few TH400 Intermediate Frictions (3 discs.)

2. 2-3 3-2 Accumulator had a broken Spring due to unconstrained plunger motions. Seems a mechanical-stop such as a simple dowel or a stop sleeve will make a design improvement.

3. Reverse-Apply is a band that is substantially similar to the TH400 LO-Reverse Band.
4. Engine-Braking band is "3x stronger" than TH400.
5. Overall, the"Hard Parts" are not impressive like T400 stuff. Here's why:
5A: FWD, Direct, and other clutch pack Drums are rather small diameter (~4.5") & made of corrogated Stamped steel. The stamped steel might be fine.
5B: Planetary gearset shows biggers gear diameters than TH400 but so what; the teeth are smaller cross-section, higher pitch for quietness, and is a 3-planet rather than 4-planet format.
5C: Input shaft not pressed-in fully for spline mating to FWD drum. Input shaft extension is tiny, has rounded splines, and appears to be a "fusible-link". If the Input shaft extensiont were to break under load, then you'd probably be able to drive home in some sort of gear.
6. Overall, the Case is impressive once the Bell-housing is whacked-off. Sems Easier to understand than a TH400. (I'm not fully understanding the 4R70W yet though, due to lack of time into this forray).
7. Front Pump & Tail shaft are impressive.
8. Stock TQ Converter is 13" and quite long. Adaptive Bell Housing WILL have problems with fitting the Converter into the PMD engine flange. Bell spacers appear to be needed: Perhaps a scatter plate (or stack of scatter plates) from a stick housing. I plan to use the stock converter (mine is the Factory's latest design) because the Hi-Po Converter prices are waaay top-shelf and may not feature the lock-up ability.

9. Bonus: 8.8 Rear Input Yoke appears superior to GM's U-joint straps.

The HIS summary thus far: The 4R70W is an incremental evolution of the AOD, cheap & easy to find, and appears to be suitable for Street, yet remains illusive to "see" how it can survive Slicks & >550FT-Lbs TQ.

The >900 HP claims are more than just 1 vehicle, with (from what I understand to be) stock hard-parts. Me thinks the 4R70W is in the PowerGlide weiht-limit zone; can survive in light cars. Likely to BUST the extension shaft, the input shaft or ClutchPack splines in a 3800Lb car with PMD power.

Seems that if the 4R70W was to grenade it will probably not puncture the case, probably not contaminate the Converter, so a fella could bring a spare 4R70W puppy to the track and actually swap-out the dead/scattered unit if it comes to that. The fella would be "out about $100 at most for each grenade, So, "Hey, more core parts." HIS