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My TJ-6 conversion from a 99 Sahara

35329 Views 50 Replies 10 Participants Last post by  chop110
This project started three years ago and was originally documented in the "Builder's Corner" forum...

Well, I have decided to follow in the footsteps of a few talented individuals before me and stretch my TJ tub and frame by 15”. A couple examples of my inspiration can be found on the following links (Thank you, 'Ziptie' Jason and ‘Kelowna’ Mike).

bctj's 108" TJ. the TJ6

Ziptie's Tj-6 build

I don’t know who coined the “TJ-6” moniker first, but I like the whole CJ-6 theme… and with their permission, I am going to run with it. Here are a couple of other 15” stretches I came across in my research.

Truth is, I always wanted an LJ. The advantages of the larger wheelbase and extra interior room can’t be denied. At one point, I was seriously considering trading my TJ for an LJ but the cost of this trade up always got in the way of this plan. It seems like LJ’s are hard to come by in general (I can’t say I blame people for wanting to keep them). Whenever one popped up, they were either high mileage Jeeps with a minimum $12K price tag or just too close to $20K. Considering that at best I can only get 6K for my 99 Sahara with almost 200K miles in the odometer, I knew I was going to pay dearly for it. Then there is the issue of the $6K I had already spent on mods over the years. I was going to have to start all over again (I just put on an AEV highline, I was not about to just give that away!!)

I then came across Mike and Jason’s impressive TJ-6 builds and others like them. As I looked into to it further, it dawned on me that this was something that was definitely within my fabrication abilities and budget.

I am licensed structural engineer by trade but do have some basic know how on metalworking and welding. Plus, I have recently dabbled in bodywork and automotive painting when I did my highline install.

Like Mike, I will use frame sections from a wrecked TJ for the frame extensions and will borrow ideas from the AEV Brute frame extension conversion. I will attempt to repair the 15” tub gaps with 18 gauge sheet metal and body filler (Some creativity will be required to effectively hide the splice seams). I will remove the soft top belt rail on the driver’s side and transplant the excess material to belt rail gap in the passenger side. I will then use a new LJ belt rail for the driver’s side.

Here is a digital previsualization of the finished product:

I will tally up all the material costs at the end along with any money I gained from selling my current soft top and frame from my TJ. So far, the biggest expense has been a new Bestop LJ top and soft top frame ($1000).

Along the way, I will incorporate upgrades to the roll cage, skid plate, suspension, and drivetrain that I would have already done on my SWB TJ anyway.
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Nothing too exciting to report. I finished all of the electrical splices, fuel line and brake line extensions. BTW, the 5/16" stock fuel line is a pain to flare. I have a bunch of leftover 5/16" and 3/16" steel flare line fittings if anyone is in need of some.

Also, redid the exhaust piping and installed a new muffler.

And here is the completed suspension and drivetrain.

Now all I need is a buddy to help me pick up the rear tub section and place it back on the frame mounts for some sheet metal work.
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I pulled my exhaust to complete the welds. I will media blast the joints and paint them for rust protection. Here is a view of the assembled exhaust system after the cat connection:

I also finally got around to putting the tub back on the frame.

The wheel well spaces look huge with the highline and the 33" tires on the OME 2.5 inch lift. I eventually want to go to 35's.

The build is getting pretty exciting now!
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More progress:

To attach the rollbar extensions, I used 6 inch long 2" diameter inserts with the same wall thickness as the factory rollbar. I also drilled some plug weld holes for additional hold.

Clamped things down, measured and remeasured to confirm the extension sections are straight and true...

Other side...

Once my extensions are welded in, it becomes pretty obvious that my earlier goof with the frame is messing with the tub alignment.

The cheap option is to shim the body mounts and get on with my life. Unfortunately, this will bug me and gnaw away inside of me for many years. If only I hade been a perfectionist back when it really counted; when the frame was being put together.

So I decided to go with the more expensive option and take the Jeep to the frame shop. Luckily the frame shop is only five minutes away from my house and is run by a trusted shop owner. It is the perfect opportunity to test drive the Jeep after one and a half years of sitting idle.
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To make it easy on the folks at the frame shop to remove the rear portion of the tub while still having functional brake lights, I used a six pin Deutch connector to tie in the extended electrical rail.

After charging the battery overnight, I placed it back on the Heep and what do you know? It drives! Drove it right out of the garage! There were no exhaust leaks but one of the fuel line connections had a slight leak. I tightened it up some more and it ran like a champ. Huge milestone.

The drive was mostly uneventful, except for the big gap on the floor and the temporary cardboard sides threatened to blow away. Brakes are functional, no wobbles from the track bar, I do need a serious steering alignment after putting in the OME lift... Drove slow the whole way, I am surprised I didn't get pulled over by the fuzz... Yes, I did put the driver's seat and seat belt back in.
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While the frame is getting fixed, I took the opportunity to cut some sheet metal for the sides of the tub.

I can't wait to ge my Jeep back. There is still quite a lot to do, but it does feel like I am getting closer to completing this. To add to my excitement, the Olive Drab Monstaliner arrived today!! Woohoo!!


I was able to take advantage of the long Memorial Day weekend to get a lot done...

The support frame for the floor extension (made from channel and L1.5x1.5x1/8" angle):

Installed... Note the welded nuts for the relocated rear seat brackets!

Once I got the tub squared with adjustable scissor jacks at four corners and measured 100 times, I welded on some rail extension supports to hold everything in place.

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Time for sheet metal work!! After seeing another Jeeper's TJ-6 build, I could not in good conscience leave the floor completely flat as I originally intended to. So, I kicked some ideas around and decided to make use of the available space for some storage compartments that will continue off from the wheel wells. It will take a lot more work, but... what the heck! It is going to be so sweet!

First, I made my templates out of posterboard material. Then, working with 18 gauge sheet metal and using a homemade press brake, various cutting tools, and a heck of a lot of hammering, I made this support bulkhead. I started out painting everything with weld though primer, later I just stopped doing this because of the time it took to get the stuff to dry and for some reason, I could not get good spot welds that held together.

Welded it in place with one half of the floor panel...

Then came the actual compartments... with some posterboard mock up work first...

Spot welded it in place...

I was running short of time and the air was feeling kind of damp. I knew it would be a while before I picked this up again so I painted the interior with primer for rust protection:

Just for kicks, I decided to test fit the side panel:

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I bent some more sheet metal for the driver side storage compartment:

And then installed it...

Now the floor panels are starting to look like something. I still need to grind down all of those spot welds.

I made a few fitting adjustments to the passenger side panel, drilled a couple of holes for the AEV flare connections and proceeded to weld it in place. This will be a slow, careful process; we don't want excessive heat to burn through the sheet metal or warp it.

Finished welding in the passenger side panel, cleaned it up, and slapped on a coat of primer to combat rust from the Houston humidity (It really takes a few hours for bare metal to start turning).

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Continuing with the interior of the side panels... I fabricated the tops of the storage compartments. In order to attach the lid hinges, I needed to weld some nuts on the insides.

I knew that creating the belt rail supports at the top of the tub gaps would be a challange. Ideally, I would have liked to have found some donor sections from a wrecked TJ tub. However, this proved to be a difficult errand. It was tough finding two unblemished 15" sections and the few that I did find, the sellers wanted me to buy the whole tub. Trying to fabricate some of my own would only result in some ugly bends (I am not that skilled).

In my search, I came across this weld-on TJ repair panel from NOR/AM that just happened to have the sloped bends that I was looking for. The sheet metal was thin (21 gauge) and felt flimsy, but in short sections, it was stiff enough to work. Best of all, it was only $60.

Look how perfectly the bends match the factory tub! :)

Passenger side welded:

After grinding everything flat, it was important to hit the top of the tub edges with some weld through primer. Once the belt rails are in place, any exposed metal in the interior gaps would be exposed to rust.

I bought a new LJ rail on the driver's side which I had no problem welding on.

For the passenger side, I fabricated one extended belt rail from the removed pieces.

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I then completed the roll bar connections using the same interior-sleeve method with plug weld holes as before:

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With major welding out of the way, I drove the TJ-6 out of the garage to hose off all of the grinding dust that had piled up in there over the last year.

After a thorough wash, it is now time to prep the exterior for bondo, primer, and painting. This next set of steps cannot be rushed.

Here are some shots of the cleaned interior.

The side compartments are not done. I am mulling starting the sheet metal work for these and then welding them on prior to applying monstaliner at a later date. It all depends on how much free time I am going to have over the next three weeks.


In preparation for the body filler, I deep cleaned the exterior, scuffed the old paint, and applied a coat of epoxy primer. The paint on the windshield frame is starting to get old and discolored so I am going to repaint it as well.

The interior is all going to be covered in olive drab Monstaliner. I need to do more sheetmetal work and welding before I can fully apply primer to the inside of the tub. Therefore, I only sprayed primer on the bare metal for rust protection.

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Application of body filler takes a lot of work. It took a lot of block sanding, reapplication of body filler, and more sanding to get everything just flat enough.

For anyone wanting to try their hand at body filler work for the first time, I have to recommend the following two products that will make your experience less painful.

Evercoat Rage Gold - This stuff rocks! Don't waste your time and money on "Bondo" brand filler (They su[k). It spreads really well and is much easier to work with.

Onion Board - A disposable mixing paper palette makes cleanup so much simpler and there is less of a chance from getting bits of dried body filler trash in your finish. Totally worth it.

The real test of your body filler skills is that layer of high build 2K primer on it. I surprised myseld with how little wet sanding I will need to do on the body panel extensions. This will really look good when the paint and clear coat are applied.

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With the arrival of some needed metal working tools, I continued my work with interior storage compartments. As before, I mocked everything up in posterboard. I then used the pieces of posterboard for my sheet metal templates. This work will take some time. In the interest of expediency, I will only work on those parts that need to be welded to the tub (I am itching to apply the Monstaliner already!


I completed fabrication of the storage compartments and set out some time to make last minute prep work before painting the interior. I removed the rollbar cage, relocated seat/seat belt attachment holes, laid out some seam sealer, and scuffed the fire out of the interior.

I then hit everything with epoxy primer.

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Next came spraying in the olive drab Monstaliner:

I can't say enough good things about this stuff. After just four days, it is tough as rock. You are supposed to let it cure for a full seven days. I'll start bolting hardware back in then. I am regretting not coating the tub rails and other bits. I ordered a touch up kit to take care of this.

With the arctic front here, I may have to wait a while for conditions to be just right to paint the exterior. In the mean time, there are still a whole bunch of other little miscellaneous details to address (Haha, this was on December of 2014... last year).
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I did some upgrade work on my original bolted OR-Fab sport cage. I made all the bolted connections welded ones. I added Poison Spyder floor stanchions. I also added additional bracing to the rear factory roll bars.

Next, I sprayed white Monstaliner on the roll cage:

Several weeks later, the weather was nice enough to paint the whole thing once and for all (Low humidity!)

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All in all, it came out great. A little drip here and there and some orange peel in the clear coat, but all of it ended up being sanded/buffed off:

"Mostly Finished" product:

I say "Mostly Finished", because there are still a whole bunch loose ends to tie up. Namely, the modified AtoZ rockers, the lids for the interior compartments, the split rear bench I am still fabricating, monstalining the plastic tan dash trim pieces, 35" tires, etc, etc... Will it ever end?!!!!
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Got some AtoZ LJ rockers. I modified them a bit with some help on the runner bar placement from Zach and his crew (Great folks to work with).


Gasket placement:

Rockers installed:

As of today (November 28, 2015), this is where my build currently stands. Interior details like the split fold and tumble seats, interior compartment lids, trim updates, and other miscellaneous mini projects are underway.
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Wow! That looks great, I wish I had the talent to do something like that. I'm looking forward to seeing the finished project.
Excellent work! It looks really good! Thanks for all the pictures and details. I am sure you have helped others who are thinking of undertaking something like this (not me). I can appreciate all the time and efforts you went through. Inspired me to practice my welding skills as I need a lot of help in that area.
Incredible work. I'm in awe.
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