Mixing and matching

[Eagle]

I have an '86 XJ with a 2.5L engine and a 5-speed. The engine was rebuilt (actually, I think it was replaced with a commercial rebuilt engine) about 30,000 miles ago. It wasn't running when I bought it, and it has been sitting for years. I'm thinking about trying to get it running, if the body isn't completely toast from sitting, for use either as a winter commuter or to donate to someone.

 

I have no problem driving a 5-speed, but the percentage of the population who can drive manual transmissions is small, and rapidly decreasing. So I'm thinking of converting it to automatic. I have a couple of XJs with AW4s behind 4.0L engines. I have a bell housing to mate an AW4 to the 2.5L. I don't think I have a 2.5L TCU.

 

Does anyone know if the TCU is the same for a 2.5L as for a 4.0L?

[89 MJ]

IMHO, anyone that would potentially want an 86 XJ would either know how to drive a manual, or would be open to learning. I'd also be concerned about it being a bit gutless having the auto behind it. To me, it doesn't seem worth the work, but I also do understand your intentions behind doing it. Sorry I'm no help on the TCU question.

[eaglescout526]

TCU’s are different. How different? Well part numbers are different I know that much. As for the internals? Well I’m not sure. Now I don’t see why a 4.0L TCU wouldn’t work, I’d just imagine it would have different shift points than what the AW4 would actually need for the 2.5L. 

[cruiser54]

Eagle, I would skip the auto. Too many unknowns and a lot of hassle. 

[pizzaman09]

For most enthusiast vehicles, manuals fetch more money.  In my 3 year search for my dream Comanche, a 4x4, 5 speed with a 4.0L, I found that the auto transmission Comanches were much slower to sell.  Manual ones generally sold very quickly.

 

I am also into 80s-90s vintage BMWs.  An automatic BMW of that vintage is typically a 20-50% value hit compared to a manual, there is an over abundance of auto ones and a short supply of manuals even though the original take rates for manual were very high on them back in the day.

 

The only place the auto is worth more is for people building highly capable off roaders.  It does make rock crawling easier.

[AZJeff]

I would agree.  Among MJ's, a 1986 is a bit more "collectable" than otehr years (except maybe a 1992).   Keeping the drivetrain original might be more attractive to someone who wants a bit of Jeep history.

 

I am thinking (hoping) someone who is savvy enough to be looking for an early MJ would be mechanically inclined enough to drive a stick.

 

Then again, I am an old guy, and learned to drive in the late 1960's on a stick.

[Eagle]

This is an XJ, not an MJ. I sold the 2.5L MJ to a fellow CC member earlier this year.

 

[gogmorgo]

I don’t think it’s worth the effort either unless you find someone who actually wants a 2.5/auto XJ. I’d be willing to bet that anyone interested in an XJ that old would either want it as original as possible or else would already be planning to pull the drivetrain out to put in something with more horsepower.
For what it’s worth, I’m finding that far more of gen Z than you’d expect are pretty keen to learn a manual transmission if they don’t already drive one.