Tendonitis in both elbows got me looking at adding power steering to my 74 FJ40 F155 engine. Already replaced the smog pump with an a/c compressor and didn't want to use a ps pump bracket on the head bolts so electric assist looked to be the best option.
To figure out how much assist torque I needed, I hung weights on the steering wheel rim and came out to be 20 ft lbs (dry park steer on brushed concrete, 235/85R16 BFG mud terrains). Saw the EZ electric column which was over $1000 and figured I could fab up something for less. Found a Kartek KTKETG electric assist which was rated at 28 ft lbs ( wanted something with mtg bolts on both sides of the unit and wanted some rough dimensions to estimate if it would fit ). Looks like this is the same assist unit in the Flaming River and DCE electronics Micro Steer kits. I created an Autodesk Inventor model of the assist unit and the stock 74 FJ40 steering column and steering shaft to figure out the rework. I uploaded a .stp file of the finished steering column assembly to GrabCad for anyone with access to a solid modeler or you can view and measure through the GrabCad 3d viewer. (note: might have stepped out the file with units set to mm cause the 3d viewer was showing super tiny inch dimensions and what looked to be the correct inch dimensions labeled as mm) Search for "FJ40 electric steering assist".
Fabrication is pretty simple with a metal lathe, welder, plasma or cutoff wheel, drill, press brake or big hammer and vise. (Note: the hole pattern on the mounting plate that comes in the Kartek kit does not have the center hole concentric to the mtg hole pattern.)
Other than fabricating the column, needed to grind about 1/8" - 3/16" clearance to the left side of the brake/clutch pedal bracket behind the dash to make sure the torque sensor wires didn't rub and added a hole and L-bracket to offset the brake pedal return spring so it didn't rub on the assist unit. Also added a stand off for the dash harness so I could off the existing tabs holding the harness which were in the area that needed the 1/8" clearance. Mounted the Ecu behind the dash on top of the brake/clutch pedal bracket. Used the flasher mounting bolt and brake pedal pivot bolt with some mounting straps I had from an electric cooling fan kit. Could also use some high temp 3m mounting tape ipo bolting. There is a diagnostic led on the harness that plugs into the ECU which is too short to reach the dash so I tie strapped it so I could see it under the dash. The assist uses a switched 12V input to turn it on and I didn't want it operating at highway speed so used the red/blue wire at the emissions VSV to ground a relay coil and disconnect the 12v input when the truck is moving. It switches off above 15mph and switches back on below 9mph which was alarming the first time I drove it and slowed down to turn into a parking lot. It felt like the steering came apart with the big decrease in steering effort. I added a manual override switch and indicator light so I would know when the electric assist was on.
