TJ CHEAP TONS
With a budget of $4000, some free scrap steel, a 4 1/2 inch angle grinder, welder and a back yard mud hole to work in, this is what I managed to accomplish.
Jeep TJ stretched 10 inches on 39s with a welded hp Dana 60 up front and sterling 10.25 rear, 4.10 gears, 4340 axle shafts. Custom axle trusses and long arm suspension including single radius arm up front and triangulated 3 link rear with out-boarded shocks. Np231 slip yoke eliminator, custom drive shafts, custom steering linkage, 1/2 inch skid plate, solid diff covers.........
I started the build by blocking the jeep up and making sure it was as level as I could and high enough so I could do all the work without having to move it any more. Next I removed all the stuff that wont be needed, stock axles, steering linkage, lower control arm frame mounts, rear upper coil mounts, tcase skid, making sure to support the tranny and t case. I also removed the gas tank. I found a 2 1/2 square tube long enough for the control arm mounts and tcase lowering bracket.
I measured the wheel base I wanted around 103 this is a 10 inch stretch in the rear, and came up with roughly 36 inches for control arms and 31 inches for the square tube that will be the lower frame mounts and skid lowering bracket. The 31 inch long 2.5x.250 square tubes were notched and a hole was drilled at each end to accept the rod ends with high misalignment spacers for the front and rear lower control arms. I used .750 chromoly rod ends for the lower control arms at one end and YJ poly bushings on the other, I used 1 inch ID schedule 80, 21 feet for $20 from the local plumbing shop, cut 4 pieces 32 inches long, notched one end and tacked the bushing sleeve into place, then I installed the tube insert in the other end and assembled the control arms.
The 1 ton axles I found on Kijiji, came with 4.10 gears, grinded all the brackets off except for the leaf spring perches, these gave me an idea of the caster angle on the front. I made control arm axle mounts from scrap 3/16 plate and the axle trusses from an old set of 3/16 rock sliders.
I blocked up the rear axle into place, level and at ride height with good pinion angle, then assembled the lower rear control arms to the frame and axle mounts and clamped the assembly into place on the bottom of the frame rail. I marked the holes for the bolts that hold the tcase skid and then drilled the frame mounts and bolted them onto the frame rails. Set the rear axle truss on and measured from the stock rear upper control arm mounts to the top center of the axle truss. The upper triangulated third link I made from a scrap piece of seamless tube 2x.250, on the frame end I used .750 chromoly rod ends and the axle end a 1.25 creepy crawler joint. Next I tacked the axle mounts and the truss into place making sure not to melt the bushings. Then I cycled the suspension
through the entire range looking at pinion angle and for any binding in the links. I made lower spring perches and tacked them into place on the axle and then modified the stock upper spring mount (that I removed from the frame earlier) centered it with the lower mount and tacked it. I used a set of TJ stock front coils in the rear, gave me the ride height I needed to clear the 39 inch tires.
For the front, I blocked up the hp Dana 60, level, square, at ride height, caster close, didn't worry about pinion angle too much because of the high pinion. Next I assembled the front lower control arms to the axle mounts, bolted them to the frame mounts then tacked the axle mounts into place. The front axle truss I made with a coil bucket on one side, because I didn't want to grind the webbing from the top of the pumpkin. It ended up giving close to 4 inches of lift over stock. I made a coil tower for the opposite side to match the height, centered them to the upper factory coil mounts and tacked them into position. Measured the distance between the top center of the axle truss to the lower control arm on the drivers side and tacked together a 21 inch link with .750 rod end on one end and poly bushing on the other. Assembled the link to the axle mount and control arm mount and tacked it in place.
I measured the length of the stock drag link on the steering since the panhard link and drag link need to be the same length and parallel to avoid bumpsteer. Made tacked up a 36 inch link with .750 rod end at each end bolted it to the stock panhard frame mount and realized I needed 2 bends in the link. I put the link between 2 trees and slid a 10 foot pipe over the link and bent it into shape then bolted it back on. I was able to use the stock panhard axle mount from the dana 60 that I removed earlier and tack it to the passenger side lower coil tower. Now that all the mounts were tacked into place I cycled the suspension, checked pinion angles and looked for any binding in the links. I had to reposition the axle control arm mounts a couple of times on the front to get maximum flex without binding. I used V8 ZJ front coils with 1 inch coil spacers, and added 2 inches to the factory bumpstops on top and 2 inches to the bottom. Once I was sure the whole suspension moved bind free, I disassembled and welded all my tack welds solid then I sleeved all my 1 inch ID suspension links with 1.5 ID schedule 80.
I used 14 inch shocks all around, for the front I made an adapter to mate the new shock to the factory upper mount and tacked a lower mount on the controlarm 2 inches from the bushing. In the rear I made a set of shock towers and frenched them into the frame behind the coil mounts, made the lower mount and tacked it into place. Then I cycled the suspension to check for shock binding and clearance issues, then welded solid. The rear axle was 4 inches narrower than the front so I added 2 inch wheel spacers to give me the same width as the front.
T-CASE AND DRIVESHAFTS
I installed a slip yoke eliminator in the tcase. Shortened an XJ front drive shaft to 21 inches. To shorten it I marked a line down the center including the yoke, to make sure it went back together correctly. I Grinded off the weld that attaches the double cardan yoke to the shaft body and gently tapped the yoke out of the tube with a hammer. I cut the drive shaft body to length and pressed the double cardan yoke back into the tube, making sure to line up my marks and that it was as square as I could get by eye. I used a 1350 to 1310 conversion ujoint to adapt the XJ shaft to fit the rear axle pinion yoke and the other end bolted on to the tcase output yoke. Once in place I used a dial indicator and mallet to get the shaft to .003 run out, 3 inches from the cut. I tacked the yoke and checked the run out again, then I welded 1 inch beads on the four opposing sides and then filled in between, to make sure the shaft didnt distort from the heat. The front drive shaft I pulled the slip shaft apart, cut one or two inches off the splined shaft and used a 1310 to 1330 conversion ujoint to mate it to the front axle pinion yoke.
For the tcase skid I used a piece off an old transport loading dock .5 inch thick plate, cut it to size, drilled mounting holes and bolted into place
using 4 inch 10.9 bolts. Since I dropped the tcase skid with the control arm frame mount, I didn't need to do a body lift to have a flat belly pan, and with 39 inch tires there is roughly 22 inches under the center of the Jeep.
My steering box had excessive play and was leaking, so I tried a 1998 v8 durango 4x4 box. The two lower mounting holes on the box fit the frame mount, however since my TJ is 2003, the top mounting hole didnt line up. I took a 1 inch hole saw and cut the welds around the top frame insert, marked where the new hole goes, drilled the frame with the 1 inch hole saw and welded the insert into place, filling in the holes left behind with a small plate. I installed a high pressure power steering line from a 2002 TJ and installed a pitman arm from a ZJ to give a 3 inch drop.
For the steering linkage I measured the stock tie rod and made a sleeved link just like the control arms but with .750 rod ends on each end. The Drag link I made the same way but only 36 inches long, the same length as the panhard link. I made a mount to weld to the tie rod, made sure the tires were pointed strait ahead and the steering box was in the center of its turning radius. I bolted the mount onto the drag link and bolted the other end of the drag link to the pitman arm. Then I tacked the mount to the tie rod and checked the steering lock to lock. It was ok so I welded it solid.
The tires and rims I bought off Kijiji, a tire shop managed to balance them for me so my first ride at least. If I had a vibration or something I knew it wouldn't be the tires. Since I stretched the rear wheel base and have 39s I needed to open the rear wheel openings. I used masking tape to mark the cuts for the comp corners, removed the evaporator and all the wires from behind the rear passenger side quarter and used an angle grinder to make the cuts. To make the curved cuts I used a cutting wheel that was almost finished, this made it easier to make the turns.