I know that the RX full time 5-speeds came with the d/r setting but with 3.70 final drive. I also know that the XT6 full time trannies came in only the s/r 5-speed with a 3.90 final drive. My question is, could I swap the pinion, pinion shaft and ring from the 3.90 tranny to the RX 3.70 tranny? I've heard that there are gears machined onto the pinion shaft which runs through the whole tranny right? Why couldn't the whole shaft be swapped with the one with the 3.90 pinion? Aren't the gears the same between the two trannies? I know its a lot of questions but I just wanna see if I can make it work...

What you are looking to do maybe possible, but let's get some of the basics right first. The pinion gear and pinion shaft are machined out of one peice of steel and the other gears and 1st/2nd syncro are pressed on to that shaft. On the other end on the shaft there a splines that mate with the center diff.

 

Now you can't just go and take the front diff and pinion set out of the out case and place it into another. You will need to re-shim the shaft do get the proper ring and pinion alignment. One more thing, you don't want to take the gear set on the pinion shaft and mate it with the input shaft gear set from another tranny. You'll get some gear noise if you do. What I would do is to swap the gears from one input shaft to the other. While you're at it you may want to find a D/R 5-speed and get the Hi/Lo set off of it and swap it with the set from you R/R fulltime 4WD, since the RX didn't get as low of a low range as the rest.

I also know that the XT6 full time trannies came in only the s/r 5-speed with a 3.90 final drive.

Nope! There were full time XT6s with an autotranny that came with a 3.70 final drive ratio. I have one!

if you're not concerned about retaining the d/r option, install a 5speed XT6 transmission.

 

while we're on this subject, what does the d/r trans offer that makes it so desirable? ive always owned XT6's so never really gave the d/r option much thought.

D/R=always in the powerband. Always a gear for every situation.

Yes, the wonderful thing about the F/T D/R is that the low range is geared so it perfectly splits the gears and makes a ten speed and, as said, always in the sweet spot. There are aways those times when driving agressively, powering out of a corner or blasting uphill and the gearing is a little high but shifting down a gear is too much, drop it in low range and pick up a quick 500 RPM. I love tooling around town on wet pavement in my RX in low range. A little quicker off the line too...

ok so it IS possible to swap the pinion shaft and with the gear since those are machined together and there are just gears pressed onto the shaft from what I'm reading? So it'll be pretty easy then? How would I reset my front diff since I have no special tools? But it Will work? YAY!!!!!HAPPY DANCE!!!!

 

Oh and I was refering to all XT6s with maunal trannies, not automatics:D

Um.

 

Take both trannys to a known good subie dealer, and talk to the 'old guy in the back' privately about it...im sure he can do it for $100 or for some beer.