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A wolf in Jeeps clothing - Goatbuilt 1200 LJ/TJ Chassis build


Red Skull Member
May 19, 2020
Member Number
Milwaukee, WI
This is my journey of building my dream jeep. The project is starting off as a 1997 Jeep Wrangler, a Goatbuilt 1200 TJ/LJ Chassis, Fox shocks, Spidertrax axles, and a bunch of other badass parts. I am hoping to have it ready for KOH 2020, that's the goal anyway.

Description of the chassis from the Goatbuilt website:
The concept is to build an all-out no compromise buggy that will use TJ/LJ doors, windshield, Top etc. This will be fully enclosed with functional doors and a top and all the amenities of a TJ jeep.

You will need to cut up a TJ/LJ tub and use the cowl, door surrounds, tub top rail and tail gate surround. You would also use the windshield, tailgate, hood and grill. We have fiberglass cowls, hood and grills available.

Our initial design will be based on an LJ tub length with 110″ wheel base. This uses the same proven suspension geometry with the subframe and all the suspension brackets we use on our Ibex buggy kits. The rear suspension uses 36″ trailing arms for packaging. We plan on making optional rear configurations that are TJ tub length and a comp cut version, but that will not fit a full top.

The main frame is constructed of 2 x 3 x .120 steel tube, the rear fenders are 2 x 2 x .120 tube and the main cage is 2 x .120 DOM tube. The front tubes and other tubes are 1-3/4 x .120 DOM. This will be a full CNC cut and mandrel bent weld it yourself kit, or we can weld it for you.

I started building parts for this chassis while the final design work was taking place, so I have a little bit of catching up to do. Let's start with the rear axle.

Please note, I am transferring everything from a previous build thread. I am not copying all the replies or discussions, it might not make total sense, but most of the pictures are here.
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Just look at it, would ya....

Just look at it.




First order of business was cutting the housing to length. I wanted a centered housing and slightly offset pinion, I used the Spidertrax Calculator and got everything laid out. I used a hose clamp and some Dykem blue to scribe a line on the housing to indicate the cut mark.



Once the housing was cut to length, I needed to fit the unit bearing end cups. I used a magnets to get it close enough to tack, then used a digital angle finder to get it square.




Next was to get the end cups and seal housings welded.



The truss a Goatbuilt part, Part No. 1132-263. Description from the website:

• Universal design fits 3 to 3-1/2″ axle tube diameter
• Provides optimum upper control arm geometry with the subframe.
• Laser cut and formed from our exclusive 3/16 100ksi high strength steel
• Integral lower bump stop strike pad for optional air bump mounting kit
• Designed to use 2-5/8″ wide x 5/8″ suspension joint, holes can be drill out for larger bolts, truss can be modified to use the smaller 2″ wide suspension joints.







The rear axle is about buttoned up. Just to be totally upfront, if the welds look perfect, uniform, and robotic, I DIDN'T DO THEM. Ha-ha. I have a good friend that works at the Roadster Shop, and has a motorcycle building business out of his home shop. He is an amazing fabricator and welder. I buy the beer and food, and he lays down the dimes. Check him out at FyrehillFabrications.com and @fyrehill on instagram. Onto the pictures.







Rear axle shafts, 300m, 35 spline, made by Cone industries.


Big thanks to Mike H from Wilwood. He killed it on some custom blue powdercoat for the calipers.



I am very pleased with how the rear axle turned out. However, I did notice one glaring issue that will need to be addressed. I wanted the fill cap centered on the housing, and centered on the plate it is welded to. After it was burned in, I realized it would be the first thing to hit if I was to back into a rock or obstacle. I have a few solutions in mind, but that will happen later down the road.

That is it for today. I will try to update every few days. Thanks for checking it out and following along, if not something something bleach, something something blender.....:laughing:

Spidertrax just released a few new products for their Spider9 housings. They introduced a new skid plate system and a knuckle gusset kit. I fit one of the skid plates to the rear housing. Like all Spidertrax products the fit and finish was great.





Since I had it on the table, I wanted to address the fill cap issue. I came up with a design and plotted it on a piece of .25" Domex100. I scored the material and bent it in position. Once the bends were even and I had the part fit to the housing, I welded the slot closed.










I wanted to know the weight of the axle for future reference:

Hub: 21.5 lbs
Rotor: 10.5 lbs
Caliper and bracket: 7.5 lbs
Third member: 77 lbs
Axle shafts: 27.5 lbs
Housing with link bolts: 128 lbs
Misc. plumbing: 3 lbs (estimated)
Oil: 7 lbs (estimated)
Limit strap tabs: 1 lbs (estimated)
Sway bar tabs: 2 lbs (estimated)

TOTAL REAR AXLE WEIGHT: 324.5 lbs :smokin:
The next thing I started working on was the trailing arms for the rear suspension. They are a Goatbuilt part, Part No. 4316-2-36. Description from the website:

Universal dual shock trailing arm kit. Perfect way to add dual shock mounted trailing arms to your rock crawler, Ultra4 race car or pre-runner. Our unique design keeps the lower shock mounting bolts below the center-line of the link yet maintains ground clearance under the shocks. Mounting the shocks below the link center-line forces the trailing arm upright, this lets us use a bearing on each end and not a bushing that will wear out. The laser cut box tube design simplifies the fitting and welding time for much easier assembly than our competitors.

Includes all the precision laser cut parts to build 2 trailing arms. The main component is a laser cut 2x4x .250 wall rectangular steel tube, just bend the bottom up and weld the side seam. The inner shock pocket is laser cut and formed out of 3/16 100XF steel and the side gusset plates are 1/8 100XF steel. The front bearing is a 1″ ID uniball, rear rod end is a 1″ ID X 1-1/4 RH thread. The rear rod end receiver incorporates a pinch bolt and is made of 4140 chromoly.

These are available in 2 different lengths, 36″ and 52″ center to center of the rod ends and they can be easily cut down to shorter lengths.



This is how the laser cut rectangular tube as it comes off the laser.

After cleaning and prepping the arm, I bent and tacked it in position. I took an angle grinder and a grinding wheel and made a nice v groove for the weld.





At this point I fired up my little easy bake oven and started pre-heating the square rod end receivers. Once up to temp, we welded them to the tube. While everything was still hot (keeping our interpass temps up) I quickly fit the side plates and burned them on. At this point, all the welding on the chromoly rod end receiver was complete, and they slow cooled in welding blankets overnight. A few days later I had my buddy over and he welded them out.




I worked on the front axle next.




In the same fashion as the rear axle, I marked the tubes where I wanted them cut, set it up in the band saw and cut the housing to length.

Set the pinion angle caster, squared up the inner cs and tacked them in position. I also opted to install the outboard oil seal kit as a preventative measure, I didn't want the axle tubes to get full of dirt and debris. I had Brandon from Fyrehill Fab come over and burn them in, and he did a stellar job!





Once the front truss was welded, I started getting the steering ram mounted and made some quick end links. Getting the steering ram set in a position where I could use all four clamps, use all of the ram stroke, and close to the high steer arms took a few attempts. I initially thought I would use the middle hole on the arm, and even made double shear arms, until I realized the last hole would work better. I am planning on running RCV shafts, and there is no need to have the ram/knuckle assembly capable of 50 degrees of steering, when the axle shaft will not tolerate that. Once I reamed out the high steer holes to .75", I squared everything up and tacked it in position.






Finishing the ram mount, and fitting the skid plate kit.



I used a 1/8 NPT to schrader valve to help mock up the caliper and caliper brackets. I threaded the valve in the caliper, pressurized the caliper, and made sure it was square on the rotor. Once I got them in position, we welded them on.



I am in a predicament. When I was building the blue TJ, I was never intending it to be near as hard core as this build is turning out to be. I was planning on a modest 4.8 LS, 4l60E, and an atlas transfer case with 37s. I purchased a junkyard 4.8 and 4l60 and had the trans rebuilt by a reputable builder in the area. Here is my dilemma, do I keep the 4l60 or upgrade to a 4l80 or TH400? I am not planning on having over 500 horsepower, but am planning on a healthy 6.0/6.2 or something of that nature. Am I asking for trouble with the 4l60, 40" sticky tires, 3.8 atlas and 5.13 gears in the diffs? I feel if I am ever going to upgrade, now is the time before I make all the mounts and have driveshafts made. What are your thoughts?

Long story short, I decided on a 4L80.

To give you a small update quick, a few weeks ago I was part of the FNLC, and I spent way to many hours at the lathe with sandpaper and polish. I put a quick shine on my links. The lowers are 2.25" 7075, and the uppers are 2.00".

As received vs. polishing




Jeebus... that is some serious fabrication. Even with getting laser cut parts!

I'd aspire to make as nice as an axle STAND as nice as that but the rest. 8)

Oh, and I hope the caliper paint match looks closer in person. :flipoff2: That is literally all. Well done!
I used a 1/8 NPT to schrader valve to help mock up the caliper and caliper brackets. I threaded the valve in the caliper, pressurized the caliper, and made sure it was square on the rotor. Once I got them in position, we welded them on.


I had always thought this would be a good way to hold a caliper in place, but had never seen anyone do it. Maybe it's just another common knowledge thing I had no clue of. I'm glad you posted it.