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CJ "not as limited" tube chassis build

42K views 145 replies 30 participants last post by  CJay 
#1 · (Edited)
The hardest part about starting a build thread is knowing where to begin…

I’ve been dreaming about tube chassis, full bodied crawlers for a while now. A quick look around here will tell you that I was not alone. Something about the challenge of building within the envelope of the body and a finished product which is not quite as it seems is either appealing, or as at least one friend proclaimed, stupid!

I’ve had this ’79 CJ-7 since 2001. I picked it up for the cost of a new gas tank (~$80) after the owner’s wife threatened to call the kidney foundation to pick up the “eyesore” in her driveway. I freed the stuck clutch, patched the floor pans, slapped in the new gas tank and drove the bone stock Jeep around for a while.



Soon after, I decided to sell off my TJ and transform the little stock CJ into a trail rig. 15 odd years and 2 motors, 2 transmissions, 2 t-cases, 3 sets of axles, 2 frames, 3 cages, and 3 tubs later, this is where I was at:



Specs were 104” wheelbase, 40” MT/R’s on Trailready’s, 5.0L Mustang motor, T-18, Atlas, full hydro, and leaf sprung D60/14bolt combo. Simple and worked relatively well, but was not without limitations. Regardless, I had the itch to rip into it yet again.

Plans went from just linking the front to linking front and rear, while retaining some portion of the YJ frame I had been running since around 2010. Figured that would keep a good chunk of the Jeep intact and speed the build along, but at the end of the day thoughts of a full tube chassis won out over the relatively simple, but compromised plan.

My goals became:
• Tubular chassis with structural integration of the cage, but still retaining a removable body tub
• 4 link with coilovers front and rear
• 110” wheelbase while retaining a balanced look in the front and without comp cutting the tub

With that decided, I got in a couple last runs in September of ’16 and started the teardown:

 
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#37 ·
Great looking build. I did mine a few years back and decided to run parallel uppers outside the frame rails, triangulate the lowers in the rear to keep it low and not cut into the rear seat floor.
 
#39 ·
Very cool build, If you think you had room issues try working with a 1974 Cj5 frame. Add an auto trans.......a doubler...........a Dana 300 t case.........dual 2 1/4 exhaust.......... Dodge D60 and a GM 14 in the rear, but I still feel your pain.:D
 
#41 ·
Cool build cJay! Keep the pics coming.
Thanks fellas! sgtdave--auto, doubler, and duals sounds real cozy in a CJ-5! I had my passenger header routed forward with exhaust around the front of the engine because there was simply no room with the Atlas clocked up flat. Always got odd looks on that one!

Jeepy2000--as noted earlier, your build was on constant rotation as I got going on this project. Looking forward to your next build--are you documenting it?
 
#42 ·
New build is coming along good. I got me a roller now and a ton of pics. Just been slacking on starting new a thread. I am focused on a few upgrades to BDR at the moment in preparation for koh this yr. not racing just heading down to do some wheeling and hang out with some buddies.
 
#44 ·
Nice! My original goal was to finish this in time to head cross country to KOH this year to crew for friends, and squeeze in some wheeling before or after the event. That didn't materialize unfortunately.

Anyway, looking forward to seeing pics when you get them up! Have a good time in JV.
 
#43 ·
At some point during this process, there was a bit of a lull in the build "tempo" due to some distractions...

For instance, new truck to replace my trusty '07 2500 with 5.9 and g56.

Old:

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New 3500 with old man package:

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My wife fired back by "rescuing" another dog:

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Between truck shopping and wiping dog slobber off my face, we did manage to get the front ARB installed. I had purchased this along with a hp gearset in preparation for getting a custom HP/pass drop housing, but I decided to stick with the Chevy housing. The Spartan lunchbox that I ran for 6+ years had served me well, but figured I had the ARB, so why not?

ARB installed:

Auto part Differential Tool accessory Machine Transmission part
 
#45 ·
Started on the cage next. The A pillar will go through the dash. We contemplated putting the lateral dash bar behind the dash as well but it was going to be needlessly cozy. The A pillars will have a tie in to the front shock hoops/engine cage.

Mounted the windshield and a borrowed full door (to nail the proper windshield angle.):

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Initial side "rail" bends and mockup using 2x4's for a support stucture:

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Not an exo-cage:D:

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#46 · (Edited)
"It that the pixies?", "How 'bout dat!", "Triple brutal (best Arnold voice)!", "Making Jay's Jeep great again (in best trump voice)!" Are just a few private jokes and sayings that have come about during this build.

PaulC
 
#48 ·
Time frame at this point in the build was Summer '17. Still spending plenty of time working on the CJ but lots of other stuff going on.

Ultra4 car "guest appearance" at the garage:

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And picked up this FJ40. Looks rough, but really is pretty solid! Slapped a new carb on the 350, added a little lift, swapped on some new tires/wheels, and put some new seats in it. Been a fun diversion from the Jeep and got me back out on some trails while the CJ project drags on:

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Between messing around with my new toy and Paul going wheeling out West (CO and Moab), progress was slow on the CJ for a bit. Next bit of work was mocking up position for the rear coilovers.

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#52 · (Edited)
Back to the cage/upper chassis. Got the side rails that we bent back in the spring mocked back up and started looking at B pillar options.

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Settled on a position and made the B pillars, B pillar spreader, the center a-b spreader, and harness bar:

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Added some triangulation for the b pillar:

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Tie-ins from the A pillar to the engine cage/front shock hoops:

Architecture Arch


Tube gussets at the A pillars:

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All the attachment points are using DIY 4x staked plates (DIY 4x :: Fabrication :: Staked Cage Floor Plates)

Definite concern about the base of the A pillar being staked, because it's in a different plane than the other plates and will likely be a pain in the ass to remove and install. Currently the A pillar stakes are cut really short, with little engagement, so we'll see how that works out. Might have to chamfer those two stakes, or even open the hole in the upper plate up some. That basically defeats the purpose, but the other 8 cage points will remain properly/tightly staked regardless.
 
#53 ·
Got some more parts in around this time.

Pair of PRP Premiere seats from CCOR. Got a great price and excellent service through CCOR and PRP got the custom color seats made and shipped cross country incredibly quickly:

Motor vehicle Car seat cover Car seat Car Vehicle


Sitting next to one of my old Corbeau Baja's I borrowed from my FJ40 for mockup:

Vehicle Car


Also got a shipment from Motobilt--Optima battery mount and corner blanks:

Floor Automotive exterior Bumper Table Plywood
 
#143 ·
Got some more parts in around this time.

Pair of PRP Premiere seats from CCOR. Got a great price and excellent service through CCOR and PRP got the custom color seats made and shipped cross country incredibly quickly:

View attachment 2796330

Sitting next to one of my old Corbeau Baja's I borrowed from my FJ40 for mockup:

View attachment 2796338

Also got a shipment from Motobilt--Optima battery mount and corner blanks:

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I’ll have to see if Moto built still sells the blanks. I’m building a 75 CJ6 and am in need of some.
 
#55 · (Edited)
Nice work! I really like the combo of Round/Square Tube frame along with the A pillar to engine bay tie ins. I have come to the conclusion that I need to loose most of the factory CJ frame and I really dig how yours is turning out.
 
#57 ·
Thanks! It's been nice not dealing with the constraints of the factory frame for sure.

Looks good, man. I really dig the fast back style cage.
Thanks, I like the "traditional" cage look too, and who needs more than one passenger:D?
 
#58 · (Edited)
The Motobilt corner guards blanks I ordered are swb length versions because, well, I'm cheap:D and LJ blanks will need trimming down to size anyway.

So obviously, that needed rectifying. Oops:


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8" section of 3/16" sheet mocked up and ready for welding and finishing. The mounting bolt spacing almost works out with an additional hole (which I haven't drilled/countersunk yet):

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After the armor stretch and with proposed spare tire position mock up:

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#59 ·
Back to the front with some radiator mounts...

I wonder if dimple dies will be perceived as the "diamond plate" of this generation of builds 20 years from now? This is going to be one dated pile if so:eek:

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Lower mounts in place on the crossmember:

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And upper mounts integrated into the removable shock tower brace:

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#60 ·
I'm almost caught up in the build thread to the current state of the CJ.

My original plan was to have it ready to take out to KOH this year to crew for some friends, spectate, and squeeze some wheeling in. That didn't end up happening so the new goal is April's Big Dogs Off Road Icebreaker event.

There's plenty left to do but I've been devoting a fair amount of time to it recently and in fact plan on taking all of next week to work on it. Accordingly, I hope the build thread won't stagnate in regards to meaningful updates. Wouldn't want to disappoint the 2-3 people watching!:p

So next up was some sheetmetal work to patch the inner rear tub back together. I mentioned early in this thread that I wasted a ton of time splicing in the 8" section all the way across the inner fenders and the load floor...All that work ended up as scrap on the shop floor!

Think this was pretty much the closest pic I got to the "zenith" of butchery in that department. Only thing missing in this pic is the hole I've since cut towards the rear to recess the fuel cell:

Vehicle Auto part Engine Metal


First step towards an intact rear of the tub were some new inner fenders. I picked up a set of the cheapest replacement inner fenders I could find, knowing that they would be little more than raw material. At $50 a pop, they saved me a little time cutting, breaking and bead rolling the top.

The new inner fenders needed to sit up higher than the originals for tire clearance, have cutouts for the shock towers, and have removable front panels for room to clear the cage b pillars during removal or installation (I believe Jeepyj2000 ran into a similar issue on his green TJ build.)

After some initial cutting and fitting:

Wood Floor


Circular saw Table saw Tool Tool accessory Table saws
 
#61 ·
Observant readers :D will have noted that the stock replacement inner fenders I was using were 8" too short for the application...So next up was fabricating the fill pieces for the rear corner.

Started with a break and some flanges:

Table Metal Steel


Added the corner radius:

Metal


Drilled a hole for the cage mount stake plate and gave her a test fit:

Wood Machine Table Floor Metal


The stock replacement inner fenders, of course, also had that same radius for the rear corners so I got rid of that:

Table Wood Paper Metal


Flanged the leading edge of the patch panel (Harbor Freight pneumatic flanging tool FTW!) so there was a decent transition between the two panels, and test fit the whole shooting match:

Machine Machine tool Metal


And wash, rinse, and repeat for the driver's side...
 
#62 · (Edited)
Just more sheetmetal progress, but I'm fairly happy with how it's turning out.

Got the second inner fender and rear corner bit fabbed and in place. Both sides tacked in place, and raised floor pan mocked up:

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Machine Metal


Hole in the back is for the recessed fuel cell:

Metal


Trimming and adding some flanges to the replacement floor pan section:

Table Machine Wheel Automotive wheel system Furniture
 
#68 ·
Thanks!

Fill panels adjacent to the sides of the fuel cell:

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Now, moving forward to clearing the rear upper links and mounts while still giving enough room for unimportant stuff like seats and cage removal/install:

Metal


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That's how I (bead) roll:

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