Auto Transmission to 6 Speed Manual Swap Conversion

[Northwestguy]

Hello All,
LJ here and this is my first post.
My wife is getting a newer car so I am getting her 2001 XJ Sport Auto which will ultimately become my woods access vehicle, not a hardcore rock crawler.
Not to start the debate, but I cant stand and wont drive an auto transmission. I live in the Northern lattitude snow belt and you just dont have the same control in the snow with an auto. Plus I do bit of highway driving and would love the longer legs of the 6th gear.

That being said I want to put a newer 6 Speed manual in this XJ. I know they came in later model Wranglers. The big question is will a doner wrangler (wrecking yard) manual tranny fit up to the 4.0 liter or do you need an adapter? Can I use my existing transfer case? Can you just remove the Transmission Control Unit (TCU) or is it integral to the CPU? Will just removing it cause dash warning lights.
I believe I will need from a donor the following parts:
-6 Speed Trans and Shifter
-Bell housing including Clutch
-Clutch Pedal, master cylinder and Slave cylinder
Thanks in advance for any and all input on this project.

[4.3LXJ]

LJ. I am unfamiliar with the 6 speed manual. But I have done a number of transmission conversions. There are a couple of issues with them. First is bell housing. It has to fit the 4.0. Then there is the transfer case. It has to have the six bolt New Process pattern, which it should have. But I don't know what the spline count on the six speed input is. The XJ has a 23 spline output shaft. If you don't have that on the six speed, you might be screwed on this. You cannot use the wrangler tcase without sheet metal modification under the seat since it is clocked higher than the XJ case. Also of concern is the position of the shifter. You have a console to deal with and this can be an issue for a clean installation. Another thing to consider, increasing the final gear ratio whether by larger tires or final drive ratio does not have a positive effect on milage in the XJ. It only goes down. They are already optimized from the factory for milage. Also I don't know what the final drive ratio of the six speed is, but the final drive for the five speed is lower than the auto, thus you have to have an additional 15% gain to offset this to break even

[XJ Wheeler]

I am quite interested in this thread because i have often wondered if the 6-speed auto from a TJ would be a viable option for a dd/weekend warrior XJ.

[xjrev10]

I am quite interested in this thread because i have often wondered if the 6-speed auto from a TJ would be a viable option for a dd/weekend warrior XJ.

6 speed manual you mean.

The trans is a NSG370. Used in Libbys and 05-06 TJs. I would love one in my 88 MJ project. JP mag put one in a MJ at one time.

Im having trouble finding info on using a NSG370 in a XJ/MJ. One thing I do know is the floor shifter hole needs to be cut a bit back so the shifter will work. Same goes for the NV3550 5-speed, which was used as the only manual 5-speed behind the 4.0 in 00-01 XJs. That's another trans to look at. Super low first gear. (4:1)

[XJ Wheeler]

6 speed manual you mean.



Sorry, yeah manual.

[xjrev10]

Sorry, yeah manual.

Not to derail already but I wonder if there is a 6 speed auto that could be swapped into a XJ/MJ? I love how smooth my 68RFE is in my 08 Ram dizzle pickup.

6 speed manual, hands down, would be more fun to drive!

[Pookapotamus]

How reliable is the NSG370? Is it a strong tranny?

Basically can it handle being bolted to a stroker?

Pook

[XJ Wheeler]

Not to derail already but I wonder if there is a 6 speed auto that could be swapped into a XJ/MJ? I love how smooth my 68RFE is in my 08 Ram dizzle pickup.

6 speed manual, hands down, would be more fun to drive!

Same here, The 6-speed auto in our flatbed gets 2 mpg better than the last truck we had which was quite similar otherwise, as well as being considerably quicker. It does have trouble choosing a gear when going highway speeds though. An auto would probably be more suitable for me for a dd, so my interests are peaked.

[may pop]

XJ pedals, clutch master, And probably the ECU from a 2001 XJ manual so its not looking for the Auto trans. The NV3550 in my Rubicon is nice but its not my DD. 1st gear with stock 31s is actually a little low but nice for trail riding.Here an out fit that sells packages.
http://www.high-impact.net/transmission_and_gear/stick_nv3550.htm
Not cheap but fairly complete.
Myself Id look for a wrecked 2005-2006 Rubicon 6 speed and transfer case. Wont be cheap buy less than above. Get the bellhousing and flywheel so the CPS is all in the correct spots. Also the whole clutch hyd. system.
You will have to search quite a large area to find it.

Ron

[xjrev10]

I've seen NSG370s with a Rock-Trac low miles for 2500 on eBay in the past.

[mcguyver_xj]

werent the 6-speeds used 2003-up if so it would be usable but you would need modifications in spots like some have said that tranny is prolly longer than a nv3550 which needs mods to go in a pre-00 xj then you would need to figure out tcase shifter linkage -or- cable shifter then driveshafts and tranny mount as well...


i am undergoing something along the lines i am ax15 swapping into a 1999 xj and had a np241or out of an '03 Rubicon behind my auto with little mods but to work with an ax15 i need custom rear shaft modified shifter linkage and stuff

[olds-cool]

I'm gonna stir the pot a little here... 6 speeds are overrated. I had one in my Sentra SER Spec V and I drove it like a 3 speed all the time. 1-3-6. About the only time the other gears were used was when I was passing someone, climbing a steep hill, or just banging through all of them for fun when I felt like going fast. Granted that was a car and this is a Jeep, theres not much of a difference other than 4wd off road capabilities. On normal road driving, I'll bet you still use the 1-3-6. On the trail you'll never get out of 1-2. I live in a pretty snowy area and agree that a stick is usually easier to control when the situations get a bit squirrelly. Why not stick with a direct 5 speed swap though and save the hassle? Are the final drive ratios that much better on the 6 speed?