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Building a MJ prerunner...

ren

NAXJA Forum User
Location
frenchburg, ky
Anybody know where to start looking for info? Tried JeepSpeed, only info really useful is for front axle. Wanting to make my '88 MJ BETTER at running fire-roads, and for trips out west, like maybe AZ, NM, Baja, etc...
Thanks in advance,
Ren
 
reinforce the uni-body (cage)
some sort of longarms up front
2wd beam axle trussed or sleeved inside
trussed and locked D44 or 9" rear
long-travel leaf springs left spring under axle
big shocks with proper valving and reseviors
air bumps
lose as much weight as possible
 
yeah, that is was I pretty much have in mind to start with. The front axle is already sleeved with, get this, 0.750" thick I/D tubing (Got to leave having a oil exploration company nearby), I am trying to find some body to cage the inside of the cab, plus bed bars,because I trust my welding for anything BUT a cage at this point in time (still learning to weld heavy stuff) considering the SkyJacker subframe/long arm kit for the front. What about using the rear D44 from a Scout II (mainly becasue I allready have it, AND it is 4.27 geared with a TIGHT L/S). What do you suggest for the rear springs? I am thinking something like National Spring or maybe Deaver. As for wieght loss, that is going to be the fun part, since this is also my DD. I am also going to re-enforce the the control arm brackets on the front axle BEFORE I go and bend them, like I did the last time that I tried to "sky" my MJ - ended up with the axle sitting about 2 inches to the passenger side. (lesson learned)
 
On the front axle: I am thinking about maybe getting a different one and then using a THINNER sleeve in it. The axle under the truck right now is HEAVY. It would probably survive a head-on wreck with a medium duty truck or a lightly loaded semi with only a few scratches on it.
 
ren said:
On the front axle: I am thinking about maybe getting a different one and then using a THINNER sleeve in it. The axle under the truck right now is HEAVY. It would probably survive a head-on wreck with a medium duty truck or a lightly loaded semi with only a few scratches on it.
any idea what the stock tube size is? I'd guess 2.75 .250 wall.... If that were the case I would add another .250 wall inside.
 
Don't know off-hand, but will check tomorrow. I think that may-be 3/16" might be a good size to start with. That other front axle is probably going to be used to make a trailer axle. What about the Scout II rear axle? Any thoughts on it?
 
ren said:
Don't know off-hand, but will check tomorrow. I think that may-be 3/16" might be a good size to start with. That other front axle is probably going to be used to make a trailer axle. What about the Scout II rear axle? Any thoughts on it?
does the bolt pattern match?
 
No, the ScoutII used the big pattern, but I amthinking about using some adapters to change the pattern, also, the Scout rear is a little narrower than the MJ, so the adapters would help that also. The brakes are 2 1/2" X 12" on the Scout rear, so stopping (at least the tire turning) should not be an issue.
 
personally, I wouldn't bother.

I'd get either an MJ D44, a Ford 9", Ford 8.8 or Toyota 8" with a bolt pattern matching the front.

OR, I'd grind the knuckles off a D44 front (just like if you were going to turn them) and get a piece DOM or even 4130 to put them on. It would be easy to add the brackets onto that tube since there's no diff in the way. Then with the D44 outers you can run 5on5.5, 6on5.5 or 8on6.5.
 
Took me a minute to realize that you were talking about the front axle. I could also throw on the inner "c's" from one of my CJ D30 axles, and then run the E/B 9" axle that I have stashed at the junkyard ( at least, I think it is from an E/B- it IS narrow and is a 9"). I know, I know, WHY did I not mention the 9" sooner? My wife is reading the thread with me, and asked about using it.
 
Any thoughts on how to make the UCA frame pockets stronger? Maybe plate them with some 3/16" or just redo them all together?
 
Well, I guess the DIET starts here, then. LOL Man this thing is going to be awhile in the build up, but IF it does what I want-WHOA, watch out! Where all do you think that I can strip extra weight from? I am going to end up building a stroker for this thing, too, I have a feeling. And yes, the BA 10/5 is going to be the FIRST thing to leave the truck.
 
Hey- my brain just woke up! If I change the knuckles or build a new axle, either way the brakes AND the bearings are going to be better. If I go with the big pattern wheels, then the postal Jeep in the back yard is going to loose its' front hub stuff, including the hub dust covers that BOLT on like a normal CJ hub. Not to mention the better parts availability. Man, Brett, I wish that you didn't live on the Left Coast, 'cause it would be nice to have another MJ driver to help me figure this thing out as I go.
 
18 posts in the thread, all but 3 are by the same guy...




this will be interesting...
 
If speed were my thing I would definitely upgrade both axles. The stock Jeep parts weren't really made for those kind of forces.
Jeep on!
--Pete

ComancheClub.com
 
BrettM said:
not only do you contribute nothing, you can't even count

exageration? (sp?)

my contribution would be this -


Switch the front suspention over to a double wishbone style with crossed lowers. This will allow for the minimal amount of wheel scrub (camber change) with articulation and allow much better center clearance and handling at high speeds.

i would also take a look at this thread here:
http://www.naxja.org/forum/showthread.php?t=25592

loose the bed (sell it for cash) and make something out of fiberglass to look nice and serve no function other than be there, colect stickers, and be light.

Longer - thinner(thickness of the metal) - flatter leaf springs with long shackles for better articulation in the rear. The toyota guys really like the so called "63 inch chevys" for this - and with as little weight in the back as you will have, maybe remove a leaf or two.

Id also look into some frame strengthening in the form of a beefy rear bumper (also a good place to mount thoes new shackles)

a long travel rear driveline would be a good addition

sleve the frame rails completely and have your cage and seat mount brackets welded to that.

for more weight savings - look into plexiglass windows (while they arent street legal in CA - i doubt anyone would notice - just dont let regestration lapse on the vehicle.

maybe move the batteries and anything that you can to the back of the truck to more evenly distribute the weight and get more weight over the powered axle. Also mount your spare tire above the rear axle.

i do like the above mentioned D44 hubs idea - maybe just go all out and get some Krane D44 knuckles for the front end (if you decide to keep a straight front axle)

make some 1/2 doors (4 door cherokee's of the 84-96 front door are the same IIRC) to save weight while out, but retain full doors to drive to work when it rains.

loose the front skid if you have one that has to be good for 35 lbs

If i were to chose axles for my jeep again - I would go with a Toy 8" with a factory e-locker in the rear, because they are one of the lightest strongest setups and have a drop out carrier. They also have more clearance than my Ford 9.

I would run aluminum wheels instead of steel and look into the lightest tire that i could find (in the size and type that i wanted)

if you have a bench seat, you could convert to bucket seats (dont know how that effects weight) and that would help to hold you in place while flying down the trail - though a 4-5 point harness attached to the cage would do nicely (dont think i have ever seen a harness that uses a bench seat)

make it what you want it really...

that is just the way that i would go...

(that better? :D)
 
Well, I just finished reading the thread about suspension/ mainly shock valving, and now have a better idea of how to set-up my MJs' chassis. I guess the next thing to do is start gathering the parts. Part of the challenge with this project is that the MJ is normally my work truck in the junkyard, and so, is my DD. Won't this be interesting to try and build?
 
You might want to re-asses building a Pre-runner/Daily driver. Most off-roaders or racers found out years ago that combination vehicles just don't do well in either mode.
You may have noticed that most of the hard core off roaders use a trail rig - it may be registered to get to the trails; but they don't NEED it to get to work on Monday!!

You can take 200 lbs out of a MJ with emissions and street equipment (wipers, heater, etc) but then you can't use it as a DD. Also you can remove the bed; but what are you going to do about tail lights, fenders, etc on the road?
 
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