I must admit I don't know why I didn't join sooner. This place has some of the best info on even the most radical of swaps.
I'm kind of the resident expert on RPS on the A4LD, and its newer versions the 4r44e,4r55e,5r44e,and 5r55e. I was surprised to see that someone had taken the time and effort to swap in one of the newer 55 series transmissions.(S,N,W)
I applaud your work, but would like to clarify one thing at least. The 5r55e is not really the same as the s,n,or w. The 5r55e shares its roots with the now extinct c3 trans from 70's to 80's. These were light duty transmissions at best, although they could be built stronger. In, I believe, '85 is when the first elctronically controlled ford transmission came out. This was commonly known as th a4ld.(I may be off on the date) The a4ld was simply a c3 with an elecronically controlled TCC, and in later years, 3-4 shift. The 'top of the heap' was the a4ld that came behind the 4.0. I'm sure I read somewhere on this thread or another, the entire history of th a4ld line-up. I'll spare everyone the details. The internals are tiny when compared to the s,n, or w. Even though they operate much in the same way. One unique thing about the newer 55 series was the inclusion of a 32 bit controller. This made the trannies even more versatile, and in the right hands, very tunable.(Doug904 told me once he could get it to roll over and play dead)
The gear ratio differences are a dead give away that the internals are significantly different. The newer 55 series have around a 3.25:1 first gear, whereas the 5r55e has a wimpy 2.47:1 first gear. The only way this is accomplished is a different sized planetary gear set.(larger planets, smalller sun) Another is the fact the 5r55e has a 2-piece case. The s,n,w have a one piece.
Granted the 5r55e is leaps and bounds better than the a4ld, it still won't hold up for long under the stress of high horsepower.(high meaning above 300hp) They simply don't have the line pressure to keep it together without scrapping all of the clutches. On the plus side, you can modify a couple of the 55e fluid passages to a4ld specs, and alow for for more pressure. It seems ford limited the 55e because it wanted a nice transition between shifts, and it was now using oD to split first gear into a new 2nd.(1.87:1)
In fact, there was a company offering a controller that could be adapted to the 5r55e, allowing control of oD. In a sense you could have a 6-7-speed automatic.(1st,1stover,2nd,2nd over, 3rd, 3rdover, 4th) I believe it was this site here. Also, trans-go offers a nice shift kit for the 55e.
Dead Link Removed
I'm still a believer in the longevity of the 5r55e. I have one in a '98 4.0 4x4 ranger with 326,000 miles on it. It's been serviced regulary, and still gets beat on. The shifts are still as firm as the day I bought it. It's when you start modding the engine is when you start having issues. One fellow on RPS had a S/C SOHC 4.0 pushing 298rwhp, when his newly rebuilt 55e sarting having issues coming out of first and second gear. Part of it was the PCM trying its best to save the trans, and the other was a lack of line pressure. The PCM noticed a ratio problem, and promptly locked it into one gear until he let off the gas. If you really have the money you can beef these trannies up quite a bit. I know of one company that built an a4ld that holds up to 780hp. But, it isn't cheap.
The company is in the UK.(I think) I'll have to search for the website, but it would have cost me 2500-3000 sterling to have one built.
That's not including shipping it over here.
I am glad that there is finally a feasble upgrade for even the most advantageous of us 4.0 builders.
I may try one of these 55s swaps on my upcoming 4.0 project in the ranger. For those that didn't know, the SOHC tranny will bolt-up to the older OHV. I plan on building one with around 450hp.(If I ever get that money tree to grow)