I cut off my ‘94 Toyota pickup’s IFS and replaced it with an ‘85 axle and 4” springs, using the All-Pro Off Road kit. They provide some sparse instructions, but that left a lot up to trial-and-error. This page documents some of what I learned the hard way. The swap took me a bit over 5 days, done completely by myself.
First question–what axle should you use? It’s probably easiest to go for an axle off of an older Toyota truck. You’ll want to get an ‘84 or ‘85 axle, since they have extra trussing for added strength.
Or you might consider a Dana 44, but you’ll end up spending three times more on that axle compared to the Toyota.
After hearing about all the busted birfield joints in the Toyota axles, I was considering a Dana 44. But now there’s a new “longfield” joint that is much tougher than the birfield. (And recently I heard about a “marfield” also.) So ultimately the Toyota axle looked like the best bet to me. It’s light, it’s strong, and it’s cheap.
Finding a Toyota axle can be tough, at least if you want one in good shape. I live in Utah (the four-wheeling capital of the world, it’s said) so these things seem to be in demand. I paid $300 for one that needed to be rebuilt (from Penguin Auto Wrecking in SLC).
Unless your axle is in great condition already, you’ll want to replace all the seals and bearings. All Pro has a good knuckle rebuild kit. It comes with the knuckle bearings, but not the hub bearings. While you have it torn down anyway, you might want to replace those also.
A good guide for rebuilding a Toyota axle is
First, some prep work:
I didn’t bother disassembling the IFS; I just unbolted it as one big piece. That saved me a lot of time.
Drag the IFS carcass out of the way, and cut/grind off the old IFS brackets.
The IFS engages 4WD by means of vaccuum hoses. The hoses run from the differential up to the rear/passenger corner of the engine compartment. I pulled off the hoses, cut off 2 two-inch lengths, and plugged one end of each with gasket sealer, and put the plugged hose stubs back over the nipples to seal them off.
Remove the 3 bolts at the top of each A arm, that hold the A arm onto the frame rail. On the other end of the tortion bar, pull off the lever. You need to get this off, to get the tortion bar out past the brake lines. (Mine was 9 years old, but the lever easily slipped off the end.) Now the A arm and tortion bar can be wiggled out by pulling it towards the front of the truck.
The engine mount was hidden by the A arm; it is now exposed and can be cut back.
To cut the holes for the shackle sleeves, I strongly recommend the use of a keyhole saw, rather than a torch. The frame has a diagonal brace internally; cleanly cutting through all three layers could be difficult with a torch. It was almost easy with the keyhole saw.
Get a 1-3⁄4” keyhole saw, and a drill or two that you don’t mind destroying. (My drill overheated and the bearings seized.) Use the jigs provided with the kit to position the drill. Drill from the outside of the frame. I couldn’t drill from the inside at all–not enough room, because of the transmission and exhaust. Hopefully your keyhole saw and chuck are long enough to drill all the way through, from the outside. Beware of your angle; it’s easy to get angled slightly wrong and therefore place the inside hole incorrectly. Don’t ask me how I know.
The fuel line for my truck wasn’t in the way of the hole, but be aware.
Slip the sleeves through the holes, but don’t weld them into place yet. I didn’t even tack weld them yet.
Hang the front spring hanger bracket, and tack weld it in place.
I found it useful to hang the springs next, even though the sleeves for the shackles weren’t welded in place. My truck has had a rough life, so the frame isn’t perfectly square. The only way I knew to get the springs parallel to each other was to hang them, and then adjust the sleeves.
This works especially well because the weight of the springs hold the sleeves steady while you tack weld. Once they’re tack welded in place, unbolt the springs and remove the bushings before finish-welding the sleeves.
I was a little nervous welding the passenger-side sleeve, due to the location of the fuel line. I fashioned a shield out of some very light sheet metal I had lying about, and wrapped it around the fuel line. I managed to finish welding with no problems this way.
The end is in sight! From here on, it’s all easy…
Weld the pad onto the driver’s side spring perch on the axle, so both that perches are the same height.
Bolt up the axle.
Steering is pretty simple.
The only alignment possible on this axle is to set toe-in. Toe-in should be set between 1⁄8” and 3⁄16”. Use white-out to mark a spot on the inside of each tire. Measure the distance between the two, then roll the tires half a turn, and measure between the white marks from the back side. This second measurement should be 1⁄8” to 3⁄16” greater. Adjust the tie rod until this is the case.
Of course, this measurement probably varies based on your tire size. I used the 1⁄8” - 3⁄16” spec for 35” tires.
Replace the old rubber brake lines with the steel braided lines.
The IFS brake calipers are bigger than the ‘85 brake calipers. To get the larger calipers to fit, you’ll need to grind a bit off of the shield around the rotor.
I cut off, modified, and welded back the brackets that hold the brake line to the frame.
Welding the braces for the shock hoops was difficult. On the driver’s side, I was able to weld it more easily because I already had the radiator and steering shaft out.
I got mine through Six States.