Building a MJ prerunner...

[ren]

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

[BrettM]

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

[ren]

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)

[ren]

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.

[BrettM]

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.

[ren]

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?

[BrettM]

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?

[ren]

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.

[BrettM]

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.

[ren]

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.

[ren]

Any thoughts on how to make the UCA frame pockets stronger? Maybe plate them with some 3/16" or just redo them all together?

[BrettM]

are you going to use them? I don't think they're used with the Skyjacker subframe, and definitely not with all the longarm kits out there besides teraflex.

[ren]

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.

[ren]

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.

[XJ_ranger]

18 posts in the thread, all but 3 are by the same guy...




this will be interesting...

[Pete M]

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]

18 posts in the thread, all but 3 are by the same guy...




this will be interesting...
not only do you contribute nothing, you can't even count

[XJ_ranger]

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)

[ren]

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?

[rsalemi]

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?

[Deathrunner]

http://www.bajaconcepts.com/jeep.htm

http://www.kartek.com/products/truck/jeepspeed/jeepspeed.htm

http://hannemannfiberglass.com/Jeep_Commanche.html

http://www.deaverspring.com/

Here is the better place to get your questions answered. They were very helpful with me:

http://www.jeepspeed.com/forum/

I was turned onto the rubicon express kits from the jeepspeed guys. The stuff works nicely fror them.

If I were to build one up, I would get Rubicon coils and deaver leaf packs. I have also had great luck with Sway-away Racerunner shocks. The price and quality is unbeatable. I paid 600.00 a pair for 2.5" res shocks. I think you will discover that that is quite a fair price. What is nice is that they are already thready so if you decide to go coilover down the road, you just need to get the nut kit and brace accordingly.

[ren]

To Rsalmi: as for the bed being gone, here in this state (KY), as long as you have someway to keep down how much stuff is thrown up off of the roadway, whatever will fly. I was thinking that for the tail lights, that I could just run some L.E.D. strips on the tube frame for the bed area, and DOT reflector tape.
As for the DD/Prerunner thing, I am willing to go more for the Prerunner, since most of the roads I drive on around here are either 1) BADLY needing repair, 2) gravel, 3) dirt. Besides, when/if I get tried of being flogged to death by a suspension sytem still in the R&D period, I have other Jeeps to drive. That and I love playing truck polo. ( like normal polo, but with a truck and a passenger to swing the mallet. I guess that you can call it a game of trust also, since you can get some REALLY dumb@$$ people out there trying to drive.)

[BrettM]

have you ruled out going IFS up front? a lot of fab work, but really the best way to go for pre-runner

[magoo117]

18 posts in the thread, all but 3 are by the same guy...




this will be interesting...
thats the way he pads his post count... :wave:

[Ramsey]

really? does that work?





:D

[ren]

Okay, today has been crazy and productive. I found a set of rather recent vintage leaf springs on a '97 S-10 Blazer that are about 62 1/2" long and are mostly thin leaves with 8 in the pack. I also snagged the rear end out of 98-99 Toy Taco, but I may trade or sell it, since I already have the D 44 rear from the Scout II, which is about 63"flange/flange. I went and snatched the front tube axle out of a 2wd Scout II while I was at it. This gives me matching axle widths and bolt patterns.
I also went and stole the front springs (Rancho) from my wifes XJ, along with the Terra-Flex adj. upper and lower arms (the lowers actually "twist" when articulated). Got to start somewhere, right?
As for the IFS possibility, if anything, I would most likely use the front beam set-up from a Ford Ranger if I go that way.

[BrettM]

As for the IFS possibility, if anything, I would most likely use the front beam set-up from a Ford Ranger if I go that way.

either mimicking a Toyota front end or the Ranger TTB would be a great way to go.

using those Scout axles will be a lot easier though. does the front beam axle use D44 outers? you may need some sort of custom or aftermarket steering. Also, if this is a 2wd pre-runner, you don't need to worry much about breakover clearance, so building low hanging longarms or lower hangars for the leafs won't present a problem. Sounds like a good find on the leafs, run the SUA with a good long shackle.

start shopping for some good deals on some shocks, that's going to be a huge part of making this successful.

[ren]

Yes, the Scout front axle 2wd/4wd use D30 or D44 outers, so that opens a lot of steering options. I am thinking about using the outers from my '79 FSJ Cherokee front D44, since BOTH knuckles are flat tops, and use the GM brackets and calipers allready. Just use the Scout/CJ disks and hubs, works wonders as long as you watch your wheel b/s.
I am talking to Fox shock co. in the morning about what they suggest, so I may end up having to build this thing so that I can scale it, to get the right valving/pressures.
Ohyeah, IF any body cares, the ScoutII front D44 uses a 290 u-joint on a CJ splne and length stub axle. Just thought you'd like to know.

[xuv-this]

-just keep the 30 and truss/build it. you're not gonna break it unless you lock it.
-a good cage is manditory.
-8.8 rear is pretty cheap and tough. good brakes too.
-also, get your springs done before worrying too much on shocks. the valving is pretty dependant on spring rate.
-3-4" lift w/ 31-32's will be pretty good for fire roads. the key is "hard in front and soft in rear" you could prolly swing 12 or 13" travel in the rear.

[ren]

Yeah, I thought about the 8.8, but I already have the ScoutII D44 and it is 4.27 geared with a TIGHT L/S, so that is the reasoning with that. As for the Fox shocks, like I posted I still need to get this thing wieghed after I get the rest of it built and hopefully some run time, so I can better explain to the people how the MJ is acting/reacting. The 31" tires are about the biggest this thing will see, so no prob. with the lift height. I also like the width of the Scout axles, since they are only 1.25" wider per side than the stock junk, and since my MJ is a 2wd, the front TUBE axle from the scout should be fine, since it is about 3/8" thick. I plan on making my axle brackets out of 1/4" thick steel, with plates under the LCA mounts to help keep from snagging the LCA's.

[BrettM]

Yeah, I thought about the 8.8, but I already have the ScoutII D44 and it is 4.27 geared with a TIGHT L/S, so that is the reasoning with that. As for the Fox shocks, like I posted I still need to get this thing wieghed after I get the rest of it built and hopefully some run time, so I can better explain to the people how the MJ is acting/reacting. The 31" tires are about the biggest this thing will see, so no prob. with the lift height. I also like the width of the Scout axles, since they are only 1.25" wider per side than the stock junk, and since my MJ is a 2wd, the front TUBE axle from the scout should be fine, since it is about 3/8" thick. I plan on making my axle brackets out of 1/4" thick steel, with plates under the LCA mounts to help keep from snagging the LCA's.
since you're starting with a bare tube and adding brackets, and you're only going to need a couple (3-4) inches of lift; you should raise both the upper and lower mounts on the axle so that the lower mount is flush with the bottom of the tube and the geometry stays the same. This will increase clearance, and get pretty good control arm angles even with short arms.

[ren]

Actually, that is a VERY good point, since it would "clean up" the bottom of the tube, and help to keep the nose up just a little bit more than the rear, without having to run a taller spring. Makes me happy that the Terra-flex lower arms are adjustable. If I am not mistaken, if the lca brackets move up to be flush with the bottom of the tube, then that is roughly 2",yes?

[xuv-this]

i would try out some v8 grand coils or something. mabye cut. the only reason to lift the front is to give you more sprung uptravel.

[Pete M]

Sounds like a great opportunity to pick up a crap-tastic s-10/ranger for junkyard wanderings and focus the MJ on having fun. :D
Jeep on!
--Pete

[Dingo509]

I think if I was to do this I would start with a frame from either a ranger or toyota and then make the cab fit the frame. think about it, to do it right you should have a frame or sleeve the existing MJ "frame". You have to build coilover mounts in the front (if you go this way) and different shock mounts in the rear. Built different spring/shackle mounts. Build a roll cage. And you really should move the engine back for weight balance.

I would swap to fiberglass bedsides, fenders and hood. If you do all this you have basically completele redesigned to chassis anyway to be able to mount them, so you might as well start with something that has a real frame.

Or maybe better yet remove everthing from the chassis then cut of the fram ebehind the cab and unibody in front of the cab and go from there. Time to fire up the tubing bender. This way you have the choice of front and rear suspension, placement of the fuel cell, engine, radiator, and battery. I would go long arm IFS in front and 4 link in the rear.

But then again i'm a glutton for punishment.

Dingo

[ren]

Well, I ordered my 'glass parts today. The new rear quarters', hood, and front fenders should be here in about a month, hopefully. As for anybody griping about me whacking a good MJ short bed, I am using one that got smashed down the entire drivers' side, so relax, the almost mint bed is still in the same almost mint condition that it started this project in. I am think about starting the front/rear bumber fab tomorrow, and maybe starting to bracket the front tube axle, since the rear only needed the spring pads relocated (done). Will post pix next weekend of parts and installs, if any body wants to see them. Also will be posting pix of underhood going-ons.
Later,
Ren

[Pete M]

If you'd like to post them at www.comancheclub.com/forums , we'd love to see them! :D
Jeep on!
--Pete