A Case of the Wrong Transmission NV3550 vs AX15

[2001 4x4]

Hey Gang, I bought a 2004 TJ with the 4.0 and 5-speed manual a couple months ago and got around to changing the transmission fluid. So I looked up which trans should be in my 2004....NV3550 and bought the fluid accordingly. Redline MTF. I noticed that I put 3 qts in (was supposed to be 2.25 qts) and it was close to full but didn't come running out the fill plug. I chalked it up to not be PERFECTLY level surface and went on with my day. Drove it for a few weeks and something was nagging at me.......is this the NV3550 like it should be?? So I googled pics of what an NV3550 looks like compared to an AX15. Sure enough...someone (previous owner(s)) must have swapped the trans for an AX15. So I'd been running my AX15 with MTF instead of MT90 and was half of a quart low for the last two weeks? The trans started getting louder but still shifted fine. Do you think I did any damage?

I just ordered 4 qts of MT90 and am going to do another (correct) fluid change.

 

[machoheadgames]

The MTF part itself doesn’t matter. It will run on whatever fluid you put in it. Being low isn’t ideal but I have to imagine it’s probably fine. Get it full and reevaluate but I bet you’re perfectly fine.

 

[MikekiM]

Welcome to the forums. The fluid doesn't really matter. Running low.. maybe. But if it is shifting good, you might have dodged a bullet.

NV3550 to AX15 is a common swap. I and a handful of others here have done the same. The PO did you a favor. The NV3550 can be like shifting a bag of spanners. You're fortunate you're in warm weather... cold shifts in the NV3550 need double clutching at a minimum.

 

[jjvw]

.... You're fortunate you're in warm weather... cold shifts in the NV3550 need double clutching at a minimum.

I ran my nv3550 over 120k miles all year round, including countless sub-zero temps, and never double clutched.

 

[MikekiM]

I ran my nv3550 over 120k miles all year round, including countless sub-zero temps, and never double clutched.

First to second was unpossible with mine.

 

[2001 4x4]

Thanks for the replies. Hopefully 3.5 quarts of MT-90 will have the AX15 shifting good again soon.

 

[hear]

I ran my nv3550 over 120k miles all year round, including countless sub-zero temps, and never double clutched.

Maybe I don't have enough miles on mine, but I love my NV3550. Shifts great. I don't see a lot of subzero temps, but in the low 30's during deer season (any colder than that and I'm not going outside anyway, lol).

 

[jjvw]

Maybe I don't have enough miles on mine, but I love my NV3550. Shifts great. I don't see a lot of subzero temps, but in the low 30's during deer season (any colder than that and I'm not going outside anyway, lol).

I could never figure out how the clutch worked, so I changed it to an automatic after 8 years.

 

[MikekiM]

I could never figure out how the clutch worked, so I changed it to an automatic after 8 years.

Lol.. maybe I should have done this instead of the AX15.

 

[Rickstar321]

I swapped out my NV3550 for the AX15 after I hit a washout in the road and cracked the trans housing... yeah... I hit it that hard... broke other stuff too.

I run the Redline MT90 in mine as well. The main thing you want to avoid is the sulfur based additives in GL5 lubricants, it eats at the yellow metal in the synchronizers.

The main difference I noticed between the two transmissions is that the AX15 is more mechanical feeling in the shifting.. but once you get used to it and muscle memory kicks in I rarely even think about it.

 

[2001 4x4]

T

I swapped out my NV3550 for the AX15 after I hit a washout in the road and cracked the trans housing... yeah... I hit it that hard... broke other stuff too.

I run the Redline MT90 in mine as well. The main thing you want to avoid is the sulfur based additives in GL5 lubricants, it eats at the yellow metal in the synchronizers.

The main difference I noticed between the two transmissions is that the AX15 is more mechanical feeling in the shifting.. but once you get used to it and muscle memory kicks in I rarely even think about it.

Thanks for the info! With MT-90 in it now it is shifting much better and running smooth and quiet!