Topic: Opinions Wanted

[DodgeMudder]

My Jeep is a '95 YJ SOA running Dodge fullsize front springs and 3/4 elliptical rear, hp30 front w/ 4.88s and lockright, 8.8 rear with ls, 2.5l nv3550 and np231 w/ sye, running either 33x9.50 BFG's street, 34x10.50 LTB's on trails, or 36x12.50 TSL's for mud.  I have recently blown the nv3550, must have been bad when I bought it.  I also have a couple '96 Dakotas I'm going to be sending to scrap, evidently '96 was a bad year for Dakota frames, one is a 5.2l, the other is a 3.9l, I have an NV3500 out of the 5.2l that will also bolt right up to the 3.9l.  I have read a bunch of places that an NV3550 and NV3500 are the same other than the 3550 has a removable bell housing and the 3500 does not, this is not true these are different transmissions and I can't use the parts from the NV3500 to fix the NV3550, which I tried and I wish I would have known before I tore the NV3500 apart.  Anyway this leaves me with a couple options to get my Jeep fixed so I can get back to abusing it on the trails:

1) Keep the 2.5l, buy a NV3550 from a JY hope it's better than the last one I had and be good to go.  This option will cost me $500-800 for a JY transmission which I will have to save up for as I have been off work for the last 3 months and I'm only back to being part time for now.

2) Is to swap in the 3.9l v-6 out of the Dakota w/ the NV3500 and run this set-up only thing this will cost other than some time and fab work might be a new computer as the one out of the Dakota is for an auto.

3) Is to swap in the 5.2l v-8 out of the Dakota w/ the NV3500 and run this set-up my biggest concern w/ this is the front axle will a locked hp30 live under a v-8 running 4.88s and 36's.

Thats the basics of what I'm trying to figure out and it's hard to decide between the different options as there is a bunch of pro's and con's to running all of these set-ups and my Jeep works well as it sits so changing anything worries me but adding a bigger motor and saving the money of buying a JY trans seems like a good idea, too.  Please make your choice and explain why.

Here is a pic of my Jeep as it sat before I dropped the trans:

[neale_rs]

What is a JY transmission?

If you mean the original '95 YJ transmission that came with the 2.5, its an AX-5. Swapping in an AX-15 has been done before.

[DodgeMudder]

What is a JY transmission?

If you mean the original '95 YJ transmission that came with the 2.5, its an AX-5. Swapping in an AX-15 has been done before.

After breaking gears in 3 different AX-5s I gave up on them and upgraded to an NV3550, looked at swapping to an AX-15 but the NV3550 is supposed to be stronger.

[neale_rs]

I've read conflicting opinions.  JP magazine always recommends the NV3550 but the Novak page seems to favor the AX-15 by just a bit.

I vote for keeping the 2.5.  For a larger engine, I would go with a much stronger 4 speed transmission like an SM420 or SM456.

[oldjeep]

If you go to the trouble of an engine swap, I'd stick with an auto.  My choice would be the 5.2L and then worry about the D30 later.

If you are worried about budget, then keep the 2.5L and get a new trans.  Even if you have the other engines already, you'll be way over $500-$800 in additional stuff by the time they are in and running.  You should be able to get a trans for a lot less than that anyways.

[DodgeMudder]

I've read conflicting opinions.  JP magazine always recommends the NV3550 but the Novak page seems to favor the AX-15 by just a bit.

I vote for keeping the 2.5.  For a larger engine, I would go with a much stronger 4 speed transmission like an SM420 or SM456.

The factory tq specs for the trans favors the nv3550 over the ax-15 by a decent margin, there is more aftermarket support for the ax-15 so it can built into a stronger trans but that takes some serious $$$ last time I looked at it.

If you go to the trouble of an engine swap, I'd stick with an auto.  My choice would be the 5.2L and then worry about the D30 later.

If you are worried about budget, then keep the 2.5L and get a new trans.  Even if you have the other engines already, you'll be way over $500-$800 in additional stuff by the time they are in and running.  You should be able to get a trans for a lot less than that anyways.

The only auto I have is in the 3.9lo Dakota and it is junk, besides I've wheeled auto's before never like the feel just doesn't feel like I have enough control.

The engine swaps won't have more than $100 or so into them, I can do the wiring and I will just adapt the Dakota motor mounts to the Jeep frame.

Note: I really do appreciate all the opinions and my replies are my way of trying to look at things from all sides, I'm not trying to act like an ass by just arguing for the sake of arguing.  Thanks for the replies keep them coming.

[Bounty Hunter]

JY=junkyard.

What are you doing that you've trashed 3 AX5's and now a NV3550?  The AX5 can last a long time with the correct fluid, if it's saved in time after the wrong fluid is used.

[sharpxmen]

What are you doing that you've trashed 3 AX5's and now a NV3550? 

probably using the same oil as Dave 

[aka-justin]

I vote in favor of keeping the 4 cyc., but, ultimately, it's your rig.

[Jeffy]

The main question you have to ask yourself is if you're happy with the 2.5L.  If not then swap to the 5.2L.  No reason to go to the 3.9L when you have a 5.2L.  If the 2.5L works for you then keep it.

I'd definitely go with the NV3550 over a AX-15.  The AX-15 has some of the same issues as the AX-5.  The NV3550 shouldn't be an issue.  Since you had a NV3550 in there, there's no point it not using one again.

[dwtaylorpdx]

probably using the same oil as Dave 

I'm sure your laughing with me..... 

Dave

[sharpxmen]

I'm sure your laughing with me..... 

Dave

just couldn't resist

[DodgeMudder]

What are you doing that you've trashed 3 AX5's and now a NV3550?  The AX5 can last a long time with the correct fluid, if it's saved in time after the wrong fluid is used.

I'm not doing anything other than driving and wheeling my Jeep, also use it some for basic farm work pulling trees, trailers and equipment around the fields to make it easier to hook up to the tractors.

My stock ax-5 lasted the longest and was in the Jeep till almost 100K miles, before the teeth for overdrive stripped off, I at that point bought a used trans from a wreck my buddy had and swapped it in I had it n the Jeep for a month as my DD still on 31's when I lost a tooth on the reverse gear, I lived with this for a while trying not to use reverse unless I had too (this includes pushing my Jeep back out of parking spots if I couldn't pull through) till I finally lost enough teeth off reverse that it wouldn't back up at all.  I then took the Jeep in and spent the money to have the local trans shop rebuild the AX-5, I actually gave them both of them and asked them to use the best parts out of the two plus whatever new parts were needed to get my Jeep back running and reliable again.  I drove on it for less than a month when I had a catastrophic failure of the rear drive line, broke the t-case output housing and shaft, rear drive shaft, both u-joints, and the yoke on the rear axle, so I picked up a different DD and decided to do SOA w/ 8.8, SYE and CV shaft.  Took almost a year to get the money ahead, get everything figured out on how I wanted to get it all to come out, and to get it back on the road, within two weeks of getting all this done on my first wheeling trip SOA I had reverse strip teeth again and I could no longer back up again, I tried going back to the trans shop but they only do a one year warranty on manual rebuilds.  Thats when I decided to give up on the AX-5 and go bigger, I started looking for a AX-15 to swap in, but found I could go NV3550 for the same work so that's where I headed next the NV3550 made more noise than the ax-5's had but everyone told me that was normal for that trans, then it started not wanting to go into 2nd gear felt like the syncro's were shot (I'm running Pennzoil Syncromesh fluid) I planned to live it for a while, till I tore the center of the clutch disc out and had to replace the clutch (I was driving down the road at 35 in 3rd when it went not shifting) I figured I would fix the trans while I had it out doing the clutch.  Pulled the trans apart and the shift tree is bent and second gear exploded internally destroying the syncro assemblies on both sides, was going to take $1300 in hard parts to fix my NV3550.  That's where I'm at now with trying to figure how to get my Jeep back up and running.

[DodgeMudder]

The main question you have to ask yourself is if you're happy with the 2.5L.  If not then swap to the 5.2L.  No reason to go to the 3.9L when you have a 5.2L.  If the 2.5L works for you then keep it.

I'd definitely go with the NV3550 over a AX-15.  The AX-15 has some of the same issues as the AX-5.  The NV3550 shouldn't be an issue.  Since you had a NV3550 in there, there's no point it not using one again.

This is where I'm a little lost I have always been happy w/ my 4 squirrels off road it keeps me light and well balanced it has good power in low range and works well, I've been thinking of rebuilding a spare 2.5l I have to make more power for on road, as I run a lot of highways when I do drive it and when I'm on the hills I really have to push the 4 to keep up with traffic.

With that said I also can see a real benefit to going to a bigger motor as a little more power should let me idle through stuff on the trail that I had to be on the gas for before to have enough power.  I also am a redneck and power is a good thing, so the 5.2l seems the way to go, then I look at how small a HP30 is and wonder will it live w/ 34's, V-8 power and weight, 4.88 gears, and the locker when I'm in the rocks.  I don't want to end up with a Jeep the blows an axle shaft every time I go wheeling.

After thinking of this I started to think about the 3.9l as a nice middle ground place to be, but is middle ground really a good option, especially when if I use it I will end up scrapping a v-8, and that just seems wrong to the redneck inside me.

[aka-justin]

Damn man.. well... you've been through soo much... is your front a D44 or D30?

I'm guessing your talking about a 94-96 3.9L Dakota, which is only around 175hp 200lb-ft vs a 94-96 5.2L Dakota which is around 225hp and 300lb-ft.  Unless your lead footed, I'm sure the 5.2l wouldn't be a bad choice and really isn't extreme per se.  Plus, it would be worth it on those large grades or mountain roads.