NV3550 in an '88

[jjvande]

It has the BA/10 now and it's looking like the 4.0 will become a 4.7 soon, so i need something stronger. Is the NV3550 an easy swap...i searched and i am tired. THe XJ is an '88 with the NP231 case.

THere is always the option of the AX-15, is the NV3550 better?

Thanks- J

[Lawn Cher']

It has the BA/10 now and it's looking like the 4.0 will become a 4.7 soon, so i need something stronger. Is the NV3550 an easy swap...i searched and i am tired. THe XJ is an '88 with the NP231 case.

THere is always the option of the AX-15, is the NV3550 better?

Thanks- J

What's your definition of easy? It can be done, but you'll need to change the input in your T-case from 21 to 23 spline, you'll need a new transmission mount, the bell housing and clutch hydraulics from the NV3550 XJ, in addition to the expensive tranny itself. It is stronger than the AX15.

[PapaPump]

has anyone here done this? this is a true upgrade worth the time? i have a ax15, with the way i drive, i will kill it eventually. is this the best solution?

[Ibby]

If you're going to go to the trouble and expense of swapping in a 3550, why not do a 4500? You'll never kill that...

[75SV1]

I am in the process of swapping a NV 3550 into an '88 Comanche. I would look at Advance Adapters website. Good Info. Plus they have some needed parts. Besides the spline count on the T/C, I think you will need a special throwout bearing. I believe there is a difference in the pilot diameter of the crankshafts between the years. Also, you will be converting from internal slave cylinder to external. Advance Adapters has a kit for this. You might also need the T/C shifter bracket. AA make the least expensive one. I haven't ordered mine yet. The NV 3550 uses the long style of input shaft. See AA's website for details. I would probably source a used one or buy a T/C with one. New they are a bit expensive.
I looked into the NV 4550. From what I've seen you have to cut up the transmission tunnel. Its about twice as heavy. The NV 3550 is very close to bolt in.
Tom

[KingA]

I put an NV3550 into my '87 last christmas. I got tired of blowing up those French things that were put under there. In any case, Advance Adapters sells a kit that includes everything you need to put it in (new slave, mount, throwout bearing, bellhousing, 23 spline for the t-case, etc...). It's not exactly cheap, but it's realitively easy to install when you have all the right parts.

The 3550 is the same lenth as the Peugot and goes in well. I love mine to death! I beat the hell out of it and it's never given my any problems. You can try a 4550, but Advance Adapters doesn't sell a kit for that. It's a bit shorter, lots heavier, and you got to cut a great big hole in your housing to make it fit. In my experience, the 3550 is all you'll ever need behind the 4.0.

Oh, you will have to get the 3550 reindexed for the t-case. As the holes are factory, the tcase sits up to high and hits the floorboard. I just got a machine shop to drill new holes so it fits better.

[Bronco]

In most every way that matters fit wise The AX-15 and the 3550 are the same. So you could search for AX-15 swap stuff and get useful info. The AA kit I’m sure is the nice way to do it but I did fine without it. There really isn’t anything to hard once you get the right stuff together. I had to get a small exhaust mod done by a shop but I did the rest of my POS-10 to AX-15 swap myself. For a parts list you will need:

Tcase input or Newer Tcase w/23 splines

M10x1.5 tap to move your Cross member back to existing untapped holes.

Tranny

Bell housing

Throw out bearing and assembly

An 85 CJ three speed pilot bearing (I think that’s the year I’ll check when I get home)

A clutch master and slave assembly from a later XJ



I’m not sure what you will need in the way of Tcase linkages. I cut the mount off the tunnel of mine because it was all jacked. Let me know if you have any other specific questions.

[jjvande]

Thanks for the low down. any idea what that kit costs at AA? and what is a god price for a NV3550/AX-15? found an AX-15 here in Albuquerque for $650 out of a 98...seems a little steep. No luck on the NV3550.
The np231 has to be rebuilt anyway, so changing the splines shouldnt be much more work. Clayton's cross member can have a new center section built pretty easily.

Thanks again.

-J