1991 MJ build thoughts: 2wd->4wd, lift?

[scully]

hope hes ok,
and if you need help,let me know.
you WILL need the speedo cable from the 4wd also. 2wd mj one is too short.
im still in need of one because i messed mine up taking it out.

 

[kastein]

Will do, thanks for offering. He's fine, all the airbags went off and he got thrown around a bit but had his seatbelt on. I wonder how hard it'll be to find that speedo cable... or if it'll have to end up coming from mopardiscountparts.

 

[scully]

any from a 4wd xj will work, auto or manual iirc.
if you order one, let me know.ill get one too and split shipping.
actually, i think ill need one for both mj's.
so 2/3 of shipping?
ill have to make sure theres no difference from 90-91

 

[kastein]

yikes, looking in my parts catalog it depends on the engine, 4wd/2wd, year, and whether or not it has cruise control for a 90 - I wonder if the guy who converted yours from 4cyl to 6cyl actually swapped that cable? The 91 is lucky, it's the first year of the VSS and electronic signaling, so no speedo cable.

EDIT:
Part numbers for a 90:
With cruise control:

• part number 5300 9001 (part from cruise sensor to cluster) plus:
  • 4WD: 5300 9000 (engine does not matter)
  • 2WD:
    • 2.5L/diesel: 5300 9005
    • 4.0L: 5300 9006

Without cruise control:

• 4WD: 5300 9004 (engine does not matter)
• 2WD:
  • 2.5L/diesel: 5300 9002
  • 4.0L: 5300 9003

Confusing enough? :looney:

 

[scully]

right?
thanks ken.
ill get those ordered up after im settled into the new place!

 

[kastein]

Good news, pricing looks fairly reasonable on those cables - $47 total for with cruise, $32 without (I'm assuming 4wd because I forget if yours has it.) All prices from mopardiscountparts, so you might even be able to find cheaper if you get lucky.

 

[89eliminator]

* the front coil springs are sagged so badly it looks like my XJ did when I had installed my rear 2-3" lift but still had stock front springs. Easy to fix, I have a spare set of decent stock coils leftover from my lift, will install them along with the d30.

all MJs are like this. its called "rake". so when you load the bed, the truck is level. usually a 2" coil spacer will level it out.

 

[kastein]

:doh: I should have known that.

Updates: Still haven't finished the frame. I'm thinking that will take about another two hours now that I have a bit more practice. I have an hp d30 I'll be building up to swap into my XJ soon, so hopefully we'll be starting the 4wd swap on the MJ a bit after that. Still need to pick up a 4wd-equipped aw4 and an np231, etc.

 

[bpm4x4]

make sure you pull up the carpet on the driver's side floor, you may have a small hole there.

Here is a pic of my 4x2 to 4x4 conversion, it has a few more dents now.

dana 44 front
9" rear
RE 4.5 coils with ACOS
SOA rear
35" SX Swampers (15.5 wide!)

 

[kastein]

nice! I'm trying to harass him into lifting it (because I don't feel like dealing with putting a better rear axle in SUA!) Being in the northeast, the floors are pretty much rusted out. Not as bad as mine, but they're getting there... I figured we'd pull everything and patch that up after getting the rockers and frame squared away.

 

[kastein]

Spent 5 hours last night replacing almost all of the brake lines - we need to drop the fuel tank to get the brake lines in the back routed properly, so it's still using the ghetto gangly mess left by the previous owner, which, while perfectly functional, makes me want to scream. The lines are run perfectly, bent to almost exactly match factory lines from halfway along the gas tank and forward however!

While bleeding the brakes we discovered several things... some of which I already knew/suspected. The bleeders on all the calipers and drums are really rusty and pretty close to worthless due to the rubber caps having been left off. One of the bleeders on the drums at the back is snapped off, the other one is so rusted it's oval shaped and I couldn't get a wrench on it. We had to ghetto-bleed those by loosening the flare nuts on the new lines and pumping till it ran clean+no bubbles, then tightening them back down mid-pump. The brake booster has some sort of disgusting rusted mess along the bottom that I noted on our initial inspection, I figured it would need replacing soon. Well, it's making a sucking/gurgling noise and the brakes have to be pumped to get any useful brake function out of them, so I'm pretty sure the booster is shot.

New things added to to-do list:
* rear discs off a Grand Cherokee d35 (if I can find em, might as well get disc brakes out of the swap while solving the bad rust issue and broken/rusted bleeder valves!)
* new brake booster - probably not doing a Grand swap on this.

Stupid question - couldn't find any compatibility info on brake boosters other than doing Grand Cherokee swaps for some reason :roll: so... will an 89 OEM brake booster bolt in on a 91? My gut feeling is yes but I want to be sure, especially since it's his DD now.

 

[89xj]

Spent 5 hours last night replacing almost all of the brake lines - we need to drop the fuel tank to get the brake lines in the back routed properly, so it's still using the ghetto gangly mess left by the previous owner, which, while perfectly functional, makes me want to scream. The lines are run perfectly, bent to almost exactly match factory lines from halfway along the gas tank and forward however!

While bleeding the brakes we discovered several things... some of which I already knew/suspected. The bleeders on all the calipers and drums are really rusty and pretty close to worthless due to the rubber caps having been left off. One of the bleeders on the drums at the back is snapped off, the other one is so rusted it's oval shaped and I couldn't get a wrench on it. We had to ghetto-bleed those by loosening the flare nuts on the new lines and pumping till it ran clean+no bubbles, then tightening them back down mid-pump. The brake booster has some sort of disgusting rusted mess along the bottom that I noted on our initial inspection, I figured it would need replacing soon. Well, it's making a sucking/gurgling noise and the brakes have to be pumped to get any useful brake function out of them, so I'm pretty sure the booster is shot.

New things added to to-do list:
* rear discs off a Grand Cherokee d35 (if I can find em, might as well get disc brakes out of the swap while solving the bad rust issue and broken/rusted bleeder valves!)
* new brake booster - probably not doing a Grand swap on this.

Stupid question - couldn't find any compatibility info on brake boosters other than doing Grand Cherokee swaps for some reason :roll: so... will an 89 OEM brake booster bolt in on a 91? My gut feeling is yes but I want to be sure, especially since it's his DD now.

if you need to replace the booster(assuming its a single diaphram like my 89), it make no sense to replace it with another single diaphram booster. i would do a double diaphram from a newer xj or wj(99-04 grand). get a used booster and master and be done. i got a used wj booster and master for 70$ at a JY.

 

[Jeff in VA]

X2......I swapped a 96 XJ dualie into mine last year. Hands down one of the best mods I've ever done to my MJ.

Jeff

 

[kastein]

OK, good to know - will the pushrod need to be modified? My suspicion again is no. Looking at my parts catalog the PN for the booster for US/CA, Export, and w/ABS on a 96 XJ is the same, so I'll definitely suggest that if it ends up needing one. Need to figure out the bleeding issue first though, so I'm going to hit up the junkyard for a set of d35 discs this afternoon.

 

[kastein]

Another dumb question - the only MJ I have to look at is presently driving to New Jersey, and the gas tank hangar bolts are discontinued. Can anyone with an MJ take a quick look at their gas tank hangar bolts and tell me how long the unthreaded portion of the shank is, and whether it's 3/8 UNC thread or not? Trying to figure out if a standard XJ tank hangar bolt can be substituted.

 

[ehall]

While bleeding the brakes we discovered several things... some of which I already knew/suspected. The bleeders on all the calipers and drums are really rusty and pretty close to worthless due to the rubber caps having been left off. One of the bleeders on the drums at the back is snapped off, the other one is so rusted it's oval shaped and I couldn't get a wrench on it. We had to ghetto-bleed those by loosening the flare nuts on the new lines and pumping till it ran clean+no bubbles, then tightening them back down mid-pump. The brake booster has some sort of disgusting rusted mess along the bottom that I noted on our initial inspection, I figured it would need replacing soon. Well, it's making a sucking/gurgling noise and the brakes have to be pumped to get any useful brake function out of them, so I'm pretty sure the booster is shot.

The brake cylinders on the rear drums are approx $10 each and are easy to replace.

I've never heard a booster make a gurgling sound. Still a good idea to replace the booster/MC but I don't think the booster is the noise

 

[kastein]

Yeah, I picked up a spare set of cylinders at AutismZone, and I still have the set of complete backing plates RCman gave me (thanks!) back when I was intending to regear my 8.25 still, so I'm pretty sure this weekend is going to involve rebuilding the rear brakes and finishing the brake line replacement job. Also, fuel filter is leaking so badly it drips every few seconds, so that's getting replaced too.

The booster is definitely making the strange sound - there is a really gross corroded area on the housing directly below the master cylinder mounting area, so I think the PO overfilled the master cylinder, resulting in it splashing on the paint, then 18 years worth of northeastern road salt did its thing and ate away the housing. I'm pretty sure there is some brake fluid in there between the outside of the diaphragm and the housing, resulting in the gurgling/spluttering sound when the pedal is moved. It seems to operate fine though (as near as we can tell with the brakes not bled fully) so the cylinders are getting replaced, then we'll bleed the system and see if it works right or not.

The tranny lines blew out (excessively rusted, I knew it was gonna happen eventually, had a new set on hand already) when he drove it to NJ for thanksgiving, so it got stranded down there. We drove down last weekend and replaced the lines, had to patch one together from the (luckily) non rusted section of the old line and the non-smashed section of the new line, as the United States Postal Smashers lived up to their name and flattened+mangled about the last foot and a half of the new return line.

Discovered the radiator is in extremely marginal condition, not too surprised by this. Also the engine mounts look like they could use replacing. For some reason it's running at about 170 to 180 degrees instead of the normal 210 even with a very corroded radiator, I think the thermostat may be stuck open. It's getting nearly 18mpg though so I really am not sure, need to test the gauge.

Picked up a new front driveshaft, radiator, 4wd shift lever and linkage, and some other stuff it needed at Skreed's part-out (if you're in/around Phillipsburg NJ, definitely head over there. He got T-boned by some jackass who ran a red light, it really sucks, the thing was absolutely mint aside from the accident damage) so hopefully the 4wd conversion will be starting as soon as the new front axle is ready to go in.

It's still burning transmission fluid on the exhaust when it stops, so I think either we overfilled it after changing out the lines or the front seal on the tranny is burping it out when it gets hot. Either way, should be fixed when the new transmission goes in for the 4wd conversion.

 

[kastein]

*cough*

So he ended up buying an Audi, and sold me the MJ for a little more than he paid for it - I was OK with this since he did dump a fair amount into parts fixing it up, which I would have to do otherwise.

So far - it's got a new hood (old one was screamingly ghetto looking, dented/scratched/rusted to hell) and I am working on the headliner finally. New front fenders and new doors are going on soon (with power windows, locks, and power+heated 97+ mirrors), after that full frame stiffeners, still needs brake work, and got the J-bolts for re-installing the gas tank (after doing the remaining brake lines) in the mail. I'm getting suspicious that the gas tank is rotted due to the smell so I might buy a new one preemptively.

Stuff on the list still - 4wd swap (was held up due to the front axle out of my XJ not being available as fast as I wanted, got a shard of metal in my cornea at the end of my week-o-jeep rebuild and was unable to do stuff in the evenings), now needs a new windshield, LOTS of sheetmetal work on the roof/bed. Needs the rear brake cylinders replaced still, going to do that this weekend hopefully.

I've decided I'm not lifting it either, going to leave it as the backup DD / junkyard parts mobile and hopefully give it a full body/paint job once I get some more practice on the old body panels.

 

[kastein]

here we go... I've bought a grand total of 4 different HP D30s over the last 3 months now. One being rebuilt to maybe go into my XJ or maybe get sold. One with 4.10s in it to get new pinion bearings and probably go into the XJ at this point. Two junk ones for 120 bucks, one of them with 3.07s so rotted out I just pulled parts out of it and gave the housing to a scrapper to get rid of it, the other with 3.55s and badly tweaked inner Cs, checked the tubes with my angle finder and it seems to be a straight housing so I just BFHed it into submission.

The BFHed d30 is going into the MJ in 6 hours... pictures to follow. Doing UCAs, UCA bushings, WJ LCAs, a V8 ZJ tie rod, newer stock springs, new shocks, new brake pads/rotors/calipers/hoses, motor mounts, and a transmission mount at the same time.

If you're within driving distance of Worcester MA this evening and feel like standing around drinking beer and talking about random jeep stuff... feel free to show up.

 

[kastein]

And here's some pics...

The goods, minus the UCAs and axle:

I'm normally the last guy to reuse bolts, but when the LCA bolts come off the donor WJ looking like this, they're fair game:

won't be driving for a day or two...


Here's where the guys from the south and southwest should stop reading if they think their jeeps are rusty. Cover your eyes, this is going to hurt...

What's a little coil perch rust gonna do? This isn't structural, right?

A better shot. This here is supposed to be a piece of 1/8" plate, spot welded over another piece of 1/8" plate:

Shock mounts are also in excellent shape (huh, what's that hole doing there?):

more "northeastern speed holes"

up here even our coil springs rust!

(the driver side coil spring is suspiciously new looking compared to the passenger side. Based on the previous previous owner's other repair work, I suspect that it rusted until it BROKE IN HALF and then was replaced, but he didn't feel like paying to replace both.)

Rust horror pics stop here... for a bit...
Look ma! no arms!

What was that I said about rust? Nevermind! :spin1: This is what a castle nut looks like after 19 years of northeastern salt spray.

(It went from blistered with rust and too big to fit into the socket to roughly oval shaped and not grippable at all when I tried to turn it. The cotter pin was a lost cause. I ended up grinding into one side until I was nicking the threads on the TRE, then grabbing it with vice grips and twisting back and forth with everything I had until it snapped and could be unscrewed.)

Brakes were in surprisingly good condition. They're the old allen bolt slide pin type, anyone need 2WD beam disc brakes for a 91/earlier? Also, you know how everyone gets confused at first by the torx head on the sway bar links? Mine actually unscrewed because the splines had rusted off :shocked:, it was annoying because I had to use a breaker bar with a torx bit on it to hold onto that end while turning the nut.

The other side. Compare those coil springs...