1987 MJ Questions...

saybye

NAXJA Forum User
Location
Soddy Daisy TN
I've got the chance to buy a 1987 4 cylinder automatic Comanche from a friend of mine. Seems to be a descent truck, although I haven't seen it in person yet, plan on getting over there tonight. What's this thing worth? Currently it needs a new starter and the 4x4 doesn't work on the front end. With that said, what are my options on doing away with the vacuum setup on the front? Do I need to swap to a newer model XJ Dana 30 or is there some kind of vacuum delete kit someone sells? How under powered at these 4 cylinder MJ's?



Its got a lift and 33's under it now. Basically I would keep it at that, maybe add some steelies, 34" TSL's, a front locker, fender flares, etc.
 
Buy it, build it. vac disco failure is common. Do a search. Price? Very hard to answer. Location, availability, condition, infinite amount of factors. If you are really worried about it look it up on kbb. My advice is If its what you want and you can afford it then buy it. I got the short end of the stick on mine, but it was exactly what I wanted. Its never bothered me. 4 cyl power? lol. no. dead nuts reliable? yup. Run it till you need more. Toyota guys get away with it by swapping axle gears. Just my thoughts.
 
SkinnyRidge is right, location condition and availability by you will all make the price vary. Front 4x4 not working is most likely vacuum related and can easily be deleted by swapping in some 95+ shafts and a seal, relatively cheap. With proper gearing a 4cyl can work well. I see your in TN so rust won't be an issue and it doesn't look too molested.
 
It is possible it has 4.56 gears in it already. There were a few 4 bngr MJ's that came with factory 4.56's.

I've seen 1. Also check the rear end as there is a SLIGHT chance it's a AMC 20. Not the 2 piece shaft setup like in the CJ's but the 1 piece like in the FSJ's. They were more common rears in the '86's but I've seen 1 '87 (although it was a 4.0L).

I've wheeled 4 bngr MJ's, XJ's, and TJ's. It's all about gearing with them. Run at least 4.88's for up to 33's and if you go bigger than 33's run at least 5.13's. It will be slow but will go anywhere.
 
You can also "fix" the front axle by opening up the disconnect plate and just move the collar over and throw a Zip tie around the axle to keep the collar in place. That way it will stay in the locked position all of the time.
 
With it being an 87 you could pick up an 87-90 RENIX 4.0 XJ donor and do a swap pretty easy, too. The only different part between an XJ donor and an MJ donor would be the rear driveshaft iirc. Oh, the fuel pump is a silly 14psi one on the TBI 2.5L and a 30s/40s range one on the RENIX 4.0, but iirc the hangar is the same (MJ ones are special) and the pump itself is the only difference. Hopefully someone can confirm/deny that.

Could go junkyard shopping and/or use an HO donor but you will have a much easier time just buying a 4.0 XJ of the same vintage, parking them next to each other, and unbolting/installing things until it's all there.

Not that you need to do any of this, but a 4.0 with 4.56s for what amounts to a weekend or two of parts swapping is a powerful argument to me.
 
I'd just connect the pickup and the outlet on the sending unit and mount an external pump on the framerail.
it's easy to do on the renix system since the regulator just dumps extra fuel back.
 
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