91 4.0 Auto 2Wd To 4Wd???

[motodh1983]

I know you would need a front axle, driveshaft, transfer case, rear driveshaft, and longer brakeline, but my question is with a auto trans 2wd be ok running 4x4? Thanks for the help guys.

[Geonovast]

What do you need a longer brake line for?

 

You need a 4wd trans. You cannot attach a transfercase to a 2wd transmission.

[88mjgilley]

if it is a auto trans all you haft to do is swap out the tail housing bolt up the t case and your gtg there is nothing internaly differnt between the 2wd and 4wd

[NotMatt]

You're on the right track... and yes, the 2wd trans CAN have the pieces swapped to mate up a transfer case to it... BUT....

 

You're going to need a 4wd output housing to swap on (the part on the back of the trans that the t-case bolts to) AND a 4wd output shaft because the 2wd one is longer. To change the output housing and the tail shaft, you have to almost completely disassemble the transmission. So, unless you have a junk 4wd transmission laying around to scavenge the parts, have the know-how and tools to tear apart and rebuild a transmission, and don't mind getting your hands dirty.... you're better off finding a good used 4wd unit to swap in. They're a dime-a-dozen in wrecking yards, and you can most likely get one out of the same rig you'll take the transfer case, front axle, linkages, etc from.

 

You'll need to match the output spline of the trans you choose to the input spline on the t-case... 87-90 AW4's and 231 t-cases are generally 21 spline, while 91 and later are generally 23 spline... though things change a bit on the newer XJ's and I'm not familiar with those.

[Geonovast]

if it is a auto trans all you haft to do is swap out the tail housing bolt up the t case and your gtg there is nothing internaly differnt between the 2wd and 4wd

 

Uhm, yes. Yes there is.

 

The 2wd output shafts are considerably longer than the 4wd ones, as they need provisions for the speedometer gears. I know some people on here have been able to cut down a BA 10/5's output for a T-case, but it's a good amount of work, especially for a relatively junk transmission.

[motodh1983]

Crap I thought this would be as easy as a xj swap!!

[Geonovast]

It's identical to converting an XJ to 4wd, with the except of the rear driveshaft issues.

[NotMatt]

Yeah, it's all the same... the only difference is the rear driveline length. I used parts from a donor 88 Cherokee to do the 4wd swap in mine... trans, transfercase, front axle, driveline, etc. It was a bolt-in deal.

 

The 2wd AW4 is the same in the XJ's as it is in the MJ's... so there's no reason it would be any more difficult.

[Indy91mjElim]

I am doing the same project. Can I use trans/ t-case/ axles from an 01 XJ without any issues? I have a 91 auto as well.

[Geonovast]

Is the XJ an automatic? I believe the connectors and/or sensors are different for the 97+ XJs, but you might be able to get it to work.

 

Front axle will bolt in just fine, but it will be a low pinion.

[Indy91mjElim]

Yeah XJ is an auto. Would I be looking at a VSS versus mechanical speedo? What other sensors are there? Sorry for being a newb.

[Geonovast]

Your truck already has an electric speedo, but it doesn't matter anyway, the sender in the 01 is different. However, your current sender should go into the 01's T-case just fine.