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LJ Build

37K views 178 replies 26 participants last post by  stripe157 
#1 ·
I've been collecting parts for the past year, and figured I finally have enough parts to warrant tearing the Jeep down. The plan is to build a Ultra4 4600 legal Jeep that still has the ability to hold 2 adults and 2 kids. It will be "street legal". By no means will it be a daily driver, but I want to keep it close enough to street legal, that I could drive it to the local Sonic when the weather's nice.

I'm starting off with a 2006 Jeep LJ / 4.0 / Auto.

Parts list so far:

Rear Axle:
Shaved 14 bolt
Disc conversion with Eldorado calipers
Yukon spool
5.38 r&p turned to clear shave
stock shafts

Front Axle:
89 Ford KP 60
Yukon Zip locker
Reid knuckles
4wheelsupply high steer tied into knuckles
Artec truss and ram mount for TJ swap
Yukon drive slugs
stock inner, and 35 spline 4030 outers
3/4 ton Chevy brakes

Steering:
Modified Sweet servo.
Camara z28 12:1 steerng box converted to manual
PSC DE ram (still need)

Transfer case:
Dana 300 flipped and twin sticked

Fuel:
32 gallon RCI fuel cell with blades
Walbro pickups
Walbro intank pump (still need)
EVAP will still be functional to keep the computer and inspection guy happy.

Shocks:
2.5 x 14 King smoothies
2" x 2" King bumps

Engine:
Stock for now.

Trans:
Stock for now.

Safety:
Seats (still need)
Nets (still need)
Cage (still need)

I'm sure I'm missing a bunch but this is about where I stood when I pulled it in the garage 2 weeks ago and pulled it apart.

Here's what it looked like before I pulled it in the garage.





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#2 ·
14 bolt shave was fairly uneventful. I set the angle of the diff with my angle finder. Then I used a laser level to mark where to cut. After starting a cut with a grinder on each rib, it was easy to work my way around with a saws-all. I actually made it all the way through with one blade. I should have checked my junk yard housing before I started shaving it. I didn't realize that on of the tubes was bent until after I was done. I ended up ordering some alignment
pucks and straightening the tube myself. I got the shave kit and gears from ECGS. It went together well. One spot on the bottom plate required a little clearancing. Other than that it was smooth sailing.




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#4 ·
Before I tore the Jeep apart I pre-fabed most of the rear parts to link it. To get as much up travel as possible I ended up having to make my own 14 bolt truss. Class rules prohibit cutting into the tub, and a traditional truss limits clearance. This should get me about 6" of up travel with only a 4.5" spring. I'd like to get more travel in the rear but you run out out of real-estate for springs quickly. I also pre-fabed the upper link mounts, and spring pads.

So far the best spring I've found for the rear is a Rock Krawler 4.5" spring. It will give me about 12" of total travel. Metalcloak makes one that will give me 13.5" of travel, but it lifts the jeep almost 2" higher and most of that travel is down travel, not up. Also the have been completely useless with tech support. They refuse to release "their proprietary" spring rates.

**I'm open to ideas on springs. **

As of now this is where it sits. I will fab up crossmembers for the transmission and transfer case that are independent of the skid plate. Then have one flat skid from the oil pan to the rear links, that sits 2" below the frame rails.

With the 4.5" springs and a 35" tire the skid should be at 21"




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#6 ·
I'll be keeping an eye on this build, looks pretty sweet. Looks like you already started making the truss, but if the top of the diff is your limiting factor for up travel, have you considered shaving the top of the diff as well? That's what I'm planning on doing with the 14 bolt I'm putting in my TJ, but I haven't seen any others do it yet. Did you look at the Currie springs? I'm not sure if they call it an LJ spring, but it's 4.5" vs the normal 4" they sell. Part number CE-9131RH3 I believe, my number is a bit worn off. That's what I'm running right now with about 8" of uptravel in the back on 2.5 12s and it's pretty damn sweet lol
 
#12 ·
Thanks! If those numbers are current and they have a spring rate that will work I can get 7.5” up and 6.25 down. Even if I sag with fuel, etc I’d still be in the middle of my shock travel and gat almost a full 14”.

Even if I’m over compressing them and have to buy a new set every season, it’d be worth it.

I’ll hit Currie up tomorrow.


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#15 ·
No problem, let me know if you figure out the rates, all I could ever get them to tell me is they're progressive and the first inch is like 90 lbs to compress it or something, not very helpful. But mine work great, 7-8" of up is tits, I was jumping my TJ down at KOH and hitting some big shit the front 2.0s couldn't keep up with. Then I got about 3 feet of air and bent my front axle lol
 
#14 ·
You may also want to look at Teraflex. They make a 5" lift, single rate spring. I'm building a TJ that is headed towards a 4500 car, but not sure it will actually go all the way - so it's little steps. For the time being, I am going to be running coils on the rear w/ Fox smoothies. In talking to my shock tuner (Ryan @ AccuTune) he suggested going with a single rate spring as he felt most of the dual rate springs are really too stiff. I bought a pair of the Teraflex ones to try out. Tera didn't have the compressed height, but I believe the wire was around 0.625", but fewer turns. I'll try and get some measurements tonight to estimate the compressed height and report back.
 
#36 ·
Sorry for the delay on following up on this, but I did take a few measurements on the Teraflex 5" coils. The wire is 0.650" diameter and is 5 full turns with the upper and lower coils a smaller diameter so they will collapse into each other as the spring collapses so basically it looks like the compressed length would be ~ 3.25". Free length of the coil is 16". Teraflex part 1844500. Just got them installed today, so no experience on them yet.
 
#22 ·
Made a rookie mistake. I set up and installed my gears and Zip locker, not realizing that I had to preheat and weld the Artec truss to it. I read that a leading cause of gear failure was lack of preload. I assure you mine has no lack of preload. Ended up fabing up a crude ******* case spreader with scrap and a $30 trip to Home Depot. It works remarkably well.





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#23 ·
Started mapping out the front end.

One thing I’m not sure about is the fitment of the highsteer arms and tie ins. Am I missing something? When I line up the tube for the tie in it doesn’t seem to be on a section of the high steer arm where it will meet at 90 degrees.

Am I missing something or are the arms incorrect.






2 of the 3 bolts on my Saginaw box line up with the holes where my Mercedes box mounted. I’ll have to cut out and re-sleeve the 3rd hole.



I think the steering and panhard will have room. I’ll have to fab a pitman arm and double sheer point in my highsteer arm. I think the panhard will have room to squeeze between the pitman and diff cover.







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#25 ·
The Saginaw box is out of a Camara Iroc or Pontiac W56, it’s a 12:1 box instead of 15:1. It’s only 2.25 turns lock to lock, the instead of 3. I converted it to a manual box. The power steering will be handled by a Sweet valve.


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#28 ·
In a perfect world it’d have fabed 9”s front and rear with a bunch of trick parts...

In my world 14 bolt was dirt cheap, 69” WMS matches my front, 8 x 6.5” matches my front, shaved it has the same clearance as a Dana 44, and it’s super strong. I have 37”s for rec wheeling and this combo should be able to take anything I may want to throw at it in the future.


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#29 ·
Yep. I bought stinger bumps right before I saw the new rule book. Ended up having to sell those and hunt down some air bumps. Not being able to run coilovers really complicates things, but I guess that’s the point of the class. Finding coils that fit the bill is a PITA. So far the Curry 4” coils seem to be the best fit, but John Currie told me they would probably be a little stiff and that I might end up having to get a custom set made. I’m guessing my LJ will probably weigh a little more than the LJ Currie used to race, so hopefully they work out.


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#30 · (Edited)
I'd bet you'll be fine with the Currie coils, I've got them front and rear and my TJ gets after it pretty good. If I had bumps and 2.5s in the front itd be real fast. Do the rules allow you to run IBP's or no, those would be tits.

A friend of a friend had custom coilovers springs made for his powerwagon through H&R I think, might be worth a shot if that's the route you have to take
 
#33 ·
I think I figured out how to package the 2.5” x 14” shocks and still get 7” up travel in the front.

I had to ditch the Artec mounts. Pull out the CAD


And the plasma table. Lol


But I think I found a solution. I’ll have to use 1/2” cap screw instead of regular bolts for the bottom shock bolts, but that shouldn’t be an issue. The driver side will be a little harder to package, since there’s less tube.






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#34 ·
Looks good, I like that idea. I'm sure you know already, but I'd make the shocks as easy as possible to remove and install as possible for tuning purposes. When I redo my shock mounts next go around I'm going to make the lower mount holes slotted to try and decrease the time
spent dicking around with a gantry and chain hoist to get the bolt holes to line up
 
#38 ·
Part number is in my post 1844500. Just to be clear these are rear springs. I will get a pic when I get back in the shop later. They are already installed, so it won't be as clear. They have five wraps which are at the full diameter, but then have an additional 3/4 to full wrap at each end of the spring that leads into the pig tail at the end. The OD of these last wraps is smaller than the ID of the five full size wraps, so as it compresses fully they will basically collapse completely into the 5 wrap stack on each end. Hope that makes sense.
 
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