By Glenn Davis
This article is intended to help owners of 1967 through mid of 1977 F250 4wd’s (commonly referred to as "Factory Highboys") convert their current manual steering / power assist steering setup to an integrated power steering system. I chose to utilize the power steering sector (power steering box) form an early 70′s F250 two wheel drive truck. This sector has been used by Ford on the two wheel drive trucks for many years / models – It can be identified by the three tapped mounting holes in the body (vs. the 1978-1979 F250 4wd box that had 4 mounting holes and are becoming very hard to find and expensive). On a side note, if you can find / afford the ’78-’79 4wd sector definitely go this route with the conversion, as it is almost a direct bolt on to the Highboy.
I will walk you through all the steps I took to install this on my 1972 F250 4wd. This procedure is not gospel, you may choose to do it differently, but these are the steps that worked best for me.
I bought an early 70′s two wheel drive F250 truck and robbed the steering box, pitman arm, pump and lines from it. I removed some steering components from my ’72 Highboy, namely the manual steering sector and pitman arm, intermediate shaft (this is the shaft from the end of the steering column to the steering sector), the drag link (this is the shaft from the pitman arm to the steering arm on the axle) and the drivers’ front wheel.
I cut a 3/8" plate 6" wide by 7-1/2" long (note: one corner of this plate will need to be cut at 45° x 2" to clear the engine front cross member)
Test fit the plate on the inside of the mainframe, where the old steering sector use to reside. (I actually tack welded the plate to the frame temporarily. Note that this plate will need to be removed later and match drilled) You will notice that the top flange (inner lip) of the mainframe is bent upward, I mounted my plate flush against this and set the bottom of the plate on the lower mainframe flange.
Install the pitman arm to the steering sector; orient the arm so that it points to the back of the box. Note: when installed on the truck the steering box will be oriented on the inside of the mainframe and the pitman arm will be pointing outward, under the driver side frame rail and above the leaf spring. Note: the pitman arm will need to be rotated 90° from original to work. It can be stubborn to remove since it’s a spline- taper fit. I used a small hand held propane torch and a large gear puller to remove mine.
Have a buddy help you lift the sector into place and C-clamp it against the plate. Alignment is critical, the sector must be located so that the pitman arm just clears under the mainframe and has enough room for articulation to clear above the leaf springs. I actually had to trim some sheet metal from the radiator mount to get the box in the proper location.
Once the sector is in the proper location, use a marker to transfer the mounting hole locations to the plate. Now mark the location of the plate to the mainframe.
Remove the sector, and the plate. Center punch the plate and drill three holes 15/32" for 7/16" bolts.
Take the steering sector and drill out the three tapped holes in the box to 15/32" diameter. Also you might want to take a small hand grinder / die grinder and or Dremel to grind down the area on the front of the sector so the lock washers and nuts will sit flat. Mount the plate to the back of the sector using three 7/16"-14UNC x 2" LG grade 8 bolts, jam nuts and lock washers. Orient the heads of the bolts to the backside of the plate. This in essence makes the bolts mounting studs. (Note: I used these longer bolts as ‘studs’ because it makes it easier for removal and installation of the heavy steering sector.) Once the plate is bolted tightly to the sector, skip weld the bolt heads to the backside of the plate.
Keeping the sector bolted to the plate, install the assembly to the mainframe once again. Check all clearances and articulation of the pitman arm. Tack weld the plate to the mainframe. Remove the three jam nuts, lock washers and steering sector.
Final weld the plate to the frame.
Reinstall the steering sector to the plate using the jam nuts and lock washers.
Measure from the base of the splined input shaft of the sector to the base of the output steering column shaft. Shorten the intermediated shaft to this dimension, re-weld and install. I shortened mine approximately 4".
Using the steering wheel, center the pitman arm to mid stroke. Straighten wheels to center (normal driving position) and measure from center of pitman arm hole (the hole where the tie rod/drag link bolts through) to the center of the steering arm hole.
Cut the drag link in half, shorten to the proper dimension from above. Rotate the ball joints to the corresponding angles (Note: the pitman arm is angled slightly upward on the end, approximately 25°). Weld prep both cut ends of the drag link and tack weld together. Do a quick fit-up with the drag link to ensure is will work properly and take it to a certified welder to have it finished welded. The drag link is made out of some hard material, I’m guessing, but it’s something like 1045 and needs a proper certified weld due to the forces in undergoes.
Re-install the drag link with new cotter pins on the castle nuts. Bolt drivers front wheel on and mount the corresponding pump bracket for your engine. Install pump, belt, hoses and fill with power steering fluid.
Jack-up the front end of truck so that tires are off the ground, start truck and turn the wheel fully from side to side several times to purge the system of any air. Check fluid level and repeat as necessary.