I need to know this as well. My friend is swapping me his AP2 diff with 4.44's for my AP1 with stock 4.1's... what do we need to swap our diffs?

 

You just need to make sure and torque the nut that holds the flange to the diff to the right trq spec. I re used my old nut becuase Honda didn't have one available, but its less risky getting the proper trq with a new nut.

 

You pull the ap2 flange off and replace it with aan ap1 flange and a new oil seal and nylock nut. Then you torque the nut to a few pounds under spec and keep upping the torque until it requires 12 in/lbs of turning torque to spin the flange. PuddyDad has a good thread on here that I can't seem to find right now.

 

 

Remember what should be remembered, and forget what should be forgotten.Alter what is changeable, and accept what is mutable.

 

If that nut is not new, or loctited, it will move. The pattern will change in the dif and you will destroy it. Seen it a few times already.

 

They said they were able to get it torqued to proper sequence/spec with the old nut. Must be good, I've got about 8k boosted miles on it so far. Hope it last.

 

Of course they did. A new nut has nothing to do with the ability to achieve proper torque.

So no, it won't be good. order a nut, and use blue loctite on it.

 

Dredging up an old post as I am going to be doing this shortly and am VERY glad that I am reading it NOW.

Summary: If putting AP2 diff in a AP1 car and don't want to install a new drive shaft you must:
* Buy 1 Oil seal PN: 91201-PCZ-003
* Buy 1 Pinion Washer for the flange PN: 90403-PCZ-003
* Buy 1 Lock Nut(blue loctite it) PN: 90201-PCZ-003
* Swap the flange on the AP2 Diff to the AP1 flange and re-use bolts and washers.

Bill when you put in my AP2 transmission you swapped the flange out so I figure that's the easiest way to go here too!

(Edited for accuracy)

 

AP2 bolts will not fit in an AP1 driveshaft.