7 Seater, Rock Crawler, Street Legal on a Budget?

[Mike DeChristopher]

I recently "finished" my second jeep build project and thought I would share some of the experience to drum up some forum activity, share lessons learned, and generally open myself up to rig building critism.

Starting platform:
1994 YJ, 4.0L, 5sp 166K, SOA with 2.5" BSD springs, shackle reversal, high steering kit, 4:56, Super 35 with a Detroit, trashed Dana 30 and ARB, 36 x 12.50 Swampers, on board air, optima, ragged soft top, bestop seats, no frame or body rust.

Goals:
Seating for 7,
+100 crawl ratio
Skid plates on all sides
Flat belly
DVD player
Wife drivable
Fun

to be continued....

[Jeepnharleymomma]

Cool can't wait to see some pics

[HANGMAN]

Cool can't wait to see some pics

I like pictures to.

[Mike DeChristopher]

Step 1: How long do we need?
After some reading and measuring of seats we determined pretty quickly that a scrambler length is perfect. However we didn't think the scrambler was a good fit because the extra length is all reduced width (between the fenders). Also I was concerned about the rear overhang. We decided the better route was to cut a YJ just infront of the rear axle and add to create the scrambler length. The added length would be full width and you could pass between the seats to get to the third row. After reading the bestop manual for a scrambler top, we determined the magic number to be 23.25".

[Mike DeChristopher]

https://goo.gl/photos/AV5BkmazUtSEDpkJ8

[Mike DeChristopher]

A YJ frame is a rectangular tube 4" x 2.5". There is a short straight section just in front of the rear axle front spring hanger. This is where I've seen most others have stretched the frame. I bought the same size rectangular tube for my patch. I wanted my extension to be undetectable so I chose to make a long tappered wedge cut for my butt joint. The long wedge increases the weld length significantly and should result in less stress concentration. I can always add more metal later if needed. I carefully jigged up the sections and welded it together. I added another factory looking body mount and some rustoleum and you can hardly tell that its not original.

https://goo.gl/photos/XgUinET8vcPgYwcF9

[Mike DeChristopher]

Drive line:
The YJ I bought had a 4.0L to an AX-15 with a 231 t-case with 4:56 rears. My yellow CJ has a 90:1 crawl ratio which I really enjoy, so my goal was to at least match that. I considered the following combinations:
AX-15 + NP231 with 4:1 kit gives me 70:1 for $1400
NP 235 + NP 231 gives me 82.5 for $750
NP235 + NP231 with 4:1 kit gives me 122.2 for $2000
SM420 + NP231 gives me 86.6 for $700
SM420 + NP231 with 4:1 kit gives me 128.2 for $2000
AX-15 + Atlas 2 gives me 87:1 for $2400
AX-15 + Atlas 4 gives me 204:1 for $3500
NP 235 + Dana 300 with 4:1 gives me 122.2 for $1900
AX-15 + NP231 + NP231 (doubler) gives me 127:1 for $800
AX-15 + NP205 + NP231 (doubler) gives me 92:1 for $1000

Prices are approximate but include buying used gearbox from craigslist etc (except I already have an SM420) and all new kits/adapters from AA or Novak.

Based on this matrix, I chose the NP231 doubler from Behemoth Drivetrain. The "strong box" mounts between the AX-15 and NP231. It uses the input shaft, bearing and planetary gear set from a donor NP231. It's a little over 8" long and is indexable. I rotated my t-case clock-wise until I achieved a flat belly.

[Mike DeChristopher]

With the frame stretch, addition of the t-case double, and tucking the drivetrain up I needed to cut and reweld the spring perches for both rears. The rear axle needed a 31" driveshaft and a CV joint. This was a perfect application for a Cherokee front driveshaft (no length adjustment required).  For the front shaft, I needed 51". This length requires a 3" tube. I shopped around and landed on Tom's Wood. MShar was the same price but Tom's offered a 4" slip yoke. Because I have the shackle reversal I was happy to have the added travel.

[Mike DeChristopher]

Putting body back together. I ended up using all of a 4 x 8 sheet of steel to build the floor and sides. The floor is supported by 1" square tube and angle.

https://goo.gl/photos/JrXefiP6TDA4z36F9

[Death Wobble]

Did you get any inspiration from someone else's buildup, or is this all your own concept?  Good luck with it, sounds like it'll be a real attention-getter when it's done.

[Mike DeChristopher]

I've seen a lot of jeeps over the last 13 years.

After the body work was finished I moved on to fenders. I had about 6" of tire extending beyond the existing fenders. I had a set of plastic flares but my experience has been that they get damaged/ripped off. I knew that with the extra length turning would be a challenge so I wanted to be able to slide along rocks or trees on the fenders. For the front I made an 1 1/2 pipe hoop attached to the frame that goes over the fan. Then i punched holes in the fenders for 1" pipe that would tie to the flare. I borrowed a tubing notcher which worked awesome. I also borrowed  HF pipe bender which also worked well for forminh. The flares are capped with 3/16" plate that I formed with c-clamps and a dead blow hammer.

For rock rails I used 4" x 4" x .25 angle. The rear fenders are the same concept. I bend sections of the 4" angle for rear body corner protection. The fender flares and rock rails bolt on thru the body and between the body and the body mounts on the frame.


https://goo.gl/photos/RHDPjVAh1Uwbs8B28

[Mike DeChristopher]

Since the tube fenders turned out pretty sweet (IMO). I figured I would jump right into the roll bar. I used the same tube notcher and pipe bender to fab three main hoops and 8 spreader bars. The hole saws in the tube notcher held up really well. I used the same two cutters for the whole project (+50 notches). The roll cage ties into the 4" rock rail and the body. While I was at it I added mounting plates for 6 speakers, the CB radio, and the fold down DVD player monitor. The scrambler top I bought on CL was a great fit. I only problem was that it didn't fit through the garage door!  I ended up making a telescopic mount for the main bow of the soft top with pull pins that allow the bow to drop so I can fit through the door.

https://goo.gl/photos/FJeHE3QDJV9bhp8A6

[Mike DeChristopher]

I also bent and welded up an exo-cage. A couple years ago I made one for my CJ and fell in love with the luxury of not worring about my soft top. The upper hoop for the YJ is 20 ft long. The front bolts to the roll cage around the door.

Other misc:
I swapped tail lights for flush mounted LEDs including side markers
I added a homemade truss and anti-spring wrap bar to the Dana 35.
The hoops and spreaders of the roll cage were drilled before welding so that the roll cage is my air tank.
I swapped the front shafts for ones with 297 U joints. The passenger side is now one piece. I replaced the blown ARB with a lock rite.
Added a conical K&N air filter.
Added homemade differential and gas tank skid plates.
Replaced the exhaust manifold with one with flex sections.

https://goo.gl/photos/UQHGdEvjesz9sdg28

[Keith]

Mike, That is going to be one awesome rig. I was wondering how you were going to keep the family together as they grew. This should do it. With this wheel base, you'll be keeping the front wheels planted on some of those uphill rocky climbs. I'm thinking about the time you had the front end off the ground numberous times and you finally handed the kids out before trying again. That was a great day and you put on a heck of a show.

[Mike DeChristopher]

For the seats, I installed a fold and flip bench in the rear. I had to move it back 3" for leg room. For the middle row, I used the two Bestop front seats that came with the jeep. For the front I used two Wrangler front seats that I bought on CL. The seventh seat is a child seat that's mounted between the two front seats. The front passenger seat still has room to flip forward.
I welded up a small heater box and fan setup for under the right middle row seat to provide a boost to the heating system. Its plumbed in parallel with the stock heater core. For under the other middle row seat, I built a wooden box that has a 10" subwoofer.

https://goo.gl/photos/2EFWtoCrDLfNJifCA