convert to a 4 wheel drive

[mickeyd]

Hello comanche club members. MY name is Mickeyd, new to the form. Today i purchased a 1989 comanche eliminator, i believe the motor to be a little weak, it has the air filter box full of oil. The truck has 177,000 miles and i purchase it from the man that purchased it new. Now for some help, I want to convert it to a 4 wheel drive. I was thinking about buying a cherokee donor car for all the parts. This way i will have a spare motor to rebuild. What are the best years to buy or does it make a difference? Any help would be great. Thanks Mickeyd

[ExTrEmEmJ86]

Find a year close to yours and swap everything over :thumbsup:

[Pete M]

automatic or standard trans?

 

what size tires does it have now?

 

Oil in the airbox is very common and usually does not mean the engine is bad. :thumbsup: The typical cause is just a plugged vent line (the small line at the back of the valve cover).

[FrankTheDog]

For an 89 you'll want an XJ that was built between 1/89 and 5 or so 90.

That'll keep you with the renix operating system and give you the AX15

with 23 spline output if you have a 5 speed. If you get a 1990 model year

that'll get you the later 1990-98 brakes.

If it is a standard you can use any year past 1989 to 2001 for just the transmission and transfer case parts along with the front axle and front driveshaft.

 

But, most of all, search, for this subject comes up at least once a week and all your questions have been answered at least a hundred times.

 

Don't make us do all the work of typing and answering questions when with a little effort you can have all your ?'s answered and I can enjoy my vacation.

:smart:

[Pete M]

I actually prefer newcomers to ask their questions. :thumbsup:

[mickeyd]

Sorry to put you out so much frank the dog. Hope you are having a bad day and not like this all the time. My jeep is an automatic. I will be running a 31 or 32 tall tire. The truck came out with 215-75r-15 now has 235-75r-15. Pete m I will check the vent line thanks for the info.

[ParadiseMJ]

... I will check the vent line thanks for the info.

 

Blow out the line with some carb cleaner and compressed air...make sure you have the little plastic "metered orofice" on the engine end of the vac line. You can also modify the inside of the valve cover if it continues to be a problem.

[mickeyd]

So with my automatic transmission I can use 1989 to 1996 front diff and transfer case . What automatics transmission will be best. On my conversion to 4 wheel drive

[mvusse]

Front axle can come from definitely 87 through 01 Cherokee, probably all the way back to 84. Also 97 through 06 Wrangler and 93 through 98 Grand Cherokee. Of these only the 84 through 99 Cherokee are high pinion, 91 and newer did away with the problematic central axle disconnect and 97 (96? 95?) and newer will have stronger axle shaft u joints. Actually, older ones with ABS will have the stronger u joints also.

 

You cannot bolt a transfer case onto a 2wd transmission, so your transmission will need to be swapped out as well. With 2 possible spline counts and 3 possible lengths on the transfer case input shaft, it is best to get the transmission and transfer case out of the same vehicle. For plug and play install you want one from an 97 through 90 Cherokee or Comanche with the 4.0.

[relyt120]

:hijack:

 

I'm contemplating the same conversion in the future, same year and auto 4.0l, go figure.

So seeing this being said:

For plug and play install you want one from an 97 through 90 Cherokee or Comanche with the 4.0.

 

Does it matter about having a mechanical speedo cable for this year?

[Pete M]

The mechanical and electric speedos have the same port in the t-case. :thumbsup: but the 2wd cable might not be long enough to reach the t-case. might need a 4wd one.

 

 

try to nab the little speedo gear out of the donor jeep, as you might need to swap the little stub shaft it rides on.

 

[mickeyd]

Thanks mvusse and pete m for the info. I think this will make my job easier.

[Dadinator]

So, you will need to change or modify your driveshaft as well.

FYI, you don't have to stick with an auto unless you just want to.

 

I converted mine over to a 5 speed last year and couldn't be happier. More complicated than just converting to 4x4, but not impossible.

If you do stick with the auto, the AW4 is the tranny of choice and the one that is in most 4.0 cherokee's and comanche's.

 

I was lucky enough to get a donor cherokee that was the same year as my truck, so that made things a bit easier.

 

I was going to take the motor out of it, but I don't have a hoist and Igot tired of it sitting around and just junked the donor when I got everything I needed off of it.

 

Good Luck. You'll have fun. It's frustrating, but fun too.

Pay attention to all the little details and differences between the 2 trucks.

 

Check out my build thread in my signature to get some idea of what I did.

[mickeyd]

Found a 1994 jeep grand cherokee rollover today for 500.00 still run and drives. Has the 4.o engine four wheel drive with an automatic, will this make a good donor car? I know that it has cv axle instead of u-joints, is this better or worse? It's also has 4 wheel disc brakes, will they be a problem to used on my comanche? Thanks for the help.

[mvusse]

Front axle will be low pinion, rear axle will be D35, and I believe it will come with a 42RE transmission instead of the AW4. Supposedly the CV axles are about as strong as the smaller u joints. Rear Discs will work on a Comanche, but you will have to lengthen the rod for the load sensing valve as disc brakes need more pressure than drums.

[mickeyd]

Purchase a 1991 cherokee laredo today for my donor car. It has 4.0 4wheel drive and automatic. What problems can i expect to run in to when installing in my 1989 comanche. I am changing the transfer case, front axle, transmission and front driveshaft. I know the rear driveshaft will have to be made.

[mvusse]

Don't know if the 91 TCU can communicate with the Renix sensors, and I don't know if your 89 TCU can talk to the 91 transmission. At the very least be prepared for the possibility of splicing wires to and/or from the TCU.

 

91 has the 4.0 HO using a Chrysler computer and injection system with OBD I, 89 is the earlier 4.0 using a Renault/Bendix (Renix) computer and injection system which does not do OBD.

 

Any chance you can trade that 91 for an 87 through 90?

 

I'm pretty sure the 91 TCU does not have the provision for the power/comfort switch, but is always in power mode. That really is not a problem, though. The 91 transfer case will have an electronic vehicle speed sensor while your 89 uses a mechanical one. You should be able to fit your mechanical one in the 91 transfer case, but you will need a longer cable, and I don't know if the wires from the 91 just run the speedometer, or go to the TCU as well. If the TCU needs it as well, you'll have to use your 89 TCU which may or may not plug into the 91 transmission without splicing wires.

[Dadinator]

I have a 90 TCU if you're interested.

[mickeyd]

Thanks for the info mvusse maby some one will read this and know for sure if this will work or not. Dadinator not for sure if your 1990 TCU is different than my 1989 may be the same TCU.