Transmission Options

[k1n3k]

I've got an 04 TJ Rubicon, and the old NV3550 makes a bit of noise. Its fine for now, but I forsee a replacement in the future. Back when I was in my early 20's I had a K1500 I swapped an NV4500 into and really, REALLY loved having a granny gear in there. A granny gear to me is preferable over shifting the transfer case into low for the 10-20 seconds I need it. But then being able to add that to the 4:1 transfer case when needed... So Kinda want to start spitballing ideas and start getting a plan sorted out for the future.If I need to replace the transmission, why not put in the one I want?

Are there any transmission options I should be aware of that are a better fit than the NV4500 that also provide a granny low and overdrive? I'm not against chopping sheet metal to make it all fit, but i'd prefer avoiding it. I'm good with a 5 speed or 6 speed, but overdrive and and a deep low gear are the goal.

So far my short list is either a rebuilt Dodge NV4500 for the 23 spline output, and available bellhousings
The other option I'm aware of is a Tremec TR-4050 as it seems there are kits available for that. Seems like it fits about the same as the NV4500.

I'm aware an AX-15 is pretty much a bolt in replacement, however I'm weighing other options to see what is a possibility.

 

[Woodrow]

I have an NV4500 in a GM truck and that granny is pretty low. Its big and heavy though so length may be a concern in a TJ. I don't know about adaptability but others here or @NovakConversions may be some help.

 

[cpwolf]

The 6 speed from the 05/06 NSG370 and you’ll get that low 1st gear.


(Sorry, couldn’t help myself, I’m a redneck and like fireworks)

Hahahaha

 

[mrblaine]

I have an NV4500 in a GM truck and that granny is pretty low. Its big and heavy though so length may be a concern in a TJ. I don't know about adaptability but others here or @NovakConversions may be some help.

I've never understood why anyone picks a transmission option for a TJ where you basically have to build the rig around the trans.

 

[Woodrow]

I've never understood why anyone picks a transmission option for a TJ where you basically have to build the rig around the trans.

At this point, my AX-15 is the ONLY drivetrain component I haven't changed. So, while I didn't set out to, I also have built a TJ around a transmission

 

[k1n3k]

I've never understood why anyone picks a transmission option for a TJ where you basically have to build the rig around the trans.

I've done worse, I've built the transmission once, then built the vehicle around that. Layers of bad ideas.

That thing ended up as such a hodgepodge. VW TDI, adapter plate, Suzuki Sidekick trans, Sidekick T-case chopped into a doubler, then married the divorced Samurai transfer case to that. I was hoping to be able to keep a high enough final gear ratio in high range that the TDI was happy while getting a better crawl ratio. In hindsight, should have just used a Toyota drivetrain. The Samurai t-case has a high range reduction, and lower gears make it much worse. IIRC the 6.5:1 gears give it around a 1.8:1 high range.

Then I still had to build a new tunnel, t-case mounts, rebuild a interfering crossmember....

At the end of the day, I'm thinking an AX 15 may just end up in it. The NV4500 is a heavy bitch that doesn't fit well, and the TR4050 is a nice trans, but still isn't a good size either. After seeing the install require belly pan dropped an inch and still having to be chopped to make the TR4050 fit, I'm less than pleased with that. I wouldn't mind a little sheetmetal work, but to raise the belly 2" and fit one of those two transmissions in, it would end up as extensive rework of the tunnel... Doable, but then adding in a custom belly pan and all the other associated BS, the cost of the kit, and all of the other surprises.... Just not worth it.

 

[Zorba]

SM-420 is nice and short....

(somebody had to say it!)