Power Assist To Power Steering Conversion On An F250 4×4

By Vaughn McCabe

Disclaimer:The author assumes no liability for any direct or indirect damage, injury, loss of property or life resulting from the use of these instructions. The author assumes no liability for the contents of this document or its accuracy. Follow these procedures at your own risk.

At minimum you will require the following items:
a) 77-79 power steering box and mounting bolts/nuts
b) 77-79 pitman arm
c) 77-79 power steering lines- one each of fluid pressure and fluid return
d) 77-79 draglink or 2 tie rod ends and an adjuster (max 16" in length should be enough)
e) 1 piece of 1/4" steel plate approx 5 1/4" x 8"
f) 2 pieces of 1/4" wall 2 1/2" square steel tubing approx 7 1/2" long each
g) 1 litre of ATF fluid type Dexron III/ Mercon, as suggested by the local Ford Dealer
h) a welder capable of handling 1/4" steel
i) ball joint removeal fork
j) assorted wrenches, a right angle grinder and/or cutting torch, wire brush, drill, etc etc etc
k) a machine shop to shorten your old steering shaft

Extra stuff
a) 77-79 power steering pump, the old power assist pump should work if you want to reuse it.
b) new power steering belt
c) grease gun for ball joints
d) cotter pins for ball joint nuts
e) rust paint to cover welds
f) at least a dozen beer per day
g) a few days of "free time" and a place to work on your truck
h) a friend to help and/or heckle you as mine did :)

This is the procedure as I remember it. It might not be the best way but it is the way I did it. Feel free to adjust the "instructions" as you see fit. Oh yeah I am not liable for any damages to anything or anyone caused by this conversion. Mine works hope yours does also :) :) :)

1. Find a donor vehicle, it must be an F250 with the same axle as your truck, mine has a straight front axle with leaf springs so if yours isnt this swap might not work. Remove the required parts and take a good look at the system as it is setup on the donor truck, this is how yours will look when you are done, hopefully :) The donor draglink can be used, but I find it to be a little short. I plan on getting 2 tie rod ends and an adjuster to make a new adjustable draglink in the near future. The only problem I found was that I can turn harder to the left than the right with the temporary draglink.

2. Place your truck on jack stands of course, and remove the drivers wheel. Then remove the rubber/plastic inner fender, if you have one. Next remove all the power assist stuff. The steering shaft, steering box,pitman arm, draglink, power cylinder, power steering pump, bracket and all associated hoses etc. Place all this stuff carefully in a box, except the pump and bracket if you intend on reusing them, and seal the box. Then find a dumpster or better yet a cliff to throw it over :) You will need a balljoint removeal tool to split the draglink at the drivers wheel, of course you also needed one to get the stuff off the donor truck too.

3. Separate the new steering box from everything, I left the pitman arm installed to check clearances during installation. Empty all the fluid out of the steering box, invert it over a container and cycle the pitman arm back and forth. This will result in less mess when you install the box. I found out the hard way :^ (

4. On top of the frame where the new steering box will sit, on my truck anyway, the frame isnt flat it kind of bent upwards. Cut that part off so the frame is flat on top, I used a cutting wheel. Then clean the inside of the frame up remove all the dirt/grease. Cut two pieces of 2.5" square 1/4" steel tubing to fit inside the frame between the crossmember and the rad support, I used pieces 7.5" long. You will have to "adjust them with a few cuts and grinds to fit, they go one on top of the other to make a flat surface to mount the new box to.

5. Tac-weld the square tubing in place temporarily then fit the steering box in. This is where you might have to notch the crossmember and rad support and the metal inner fender a little to get the box to fit flat and straight against the frame. You will also have to remove your rad fan shroud, if you have one I didnt. You want to get the box installed in relatively the same position as it was installed in the donor truck.

6. After the box is fitting nicely in place, this took me a few hours of cutting and adjusting as I didnt want to cut off too much :), Clamp the box in place, I used a big "C’ clamp, and mark the mounting holes on to the square tubing, you may have to adjust the tubing up and down a little to get the holes to hit on the tubing only and not on the joint between them. I got lucky and it worked the first time. Cycle the pitman arm back and forth to ensure there is adequate clearance between it and the frame and the leaf spring. It should also travel in a fairly straight line or (as I remember from High School the same geometric plane).

7. Remove the box and then the square tubing, of course remembering which one is the top and which one is the bottom. You can leave them installed to drill the mount holes but I used a drill press to get the holes straight. Drill the mount holes for the bolts, mine were 9/16", in the square tubing.Then place the tubing back in the place and mark the frame where the bolts will pass through. It is real important to get the tubing back in the exact place where it was tac-welded before or the pitman arm might hit on the frame or the leaf spring. Remove the tubing and drill the holes through the frame. These frame holes dont have to be neat or a real tight fit as you will be welding a support plate over them.

8. Manufacture a flat backing plate out of 1/4" steel to go on the outside of the frame. This will cover the old box’s mounting holes, give the frame some added strength and serve as an anchor point for the steering box bolts. You will have to measure carefully to get the holes through the plate in the correct position. Oh yeah the plate is approx 5 1/4" x 8" , but use what fits of course.

9. Re-install the tubing, and bolt it through the frame to the backing plate, make sure it is straight and tight as possible against the frame, the plate will probably bend to the contour of the frame this is good. Again ensure that the tubing is in the original position.

10. Weld the tubing in place every where they touch the frame or each other. Then weld the backing plate securly to the frame. Remove the bolts and grind the weld smooth so it wont interfere with the steering box sitting flat, unless you are a better welder than I am and you dont have to grind :) Install the steering box and mounting bolts and nuts for the last time.

11. Measure the distance from the steering box to the steering shaft out of the firewall. Cut your old steering shaft to fit ( I had to cut off 4 1/4" inches). You will have to disassemble the joint on the steering box end. Then press out the "guide pin". Drill a new hole for it the proper distance and press it back in.. Install the shortened shaft in place. Good time to make sure your steering wheel is centred, looks better that way :) Also be sure and measure the hole right. Measure from centre of old hole to the desired centre of the new hole.

12. Install the "new" draglink. As I said before I used this one temporarily it wasnt quite the right length, a little short, but it works fine. I just cant make as tight right turns as I can left. You could always get the 2 tie rods and an adjuster when you are gathering parts, that way you wouldnt have to buy the 77-79 draglink at the scrapper.

13. Install your power steering pump, bracket and lines. I used the new pump but the old one should work also. Install the power steering belt and tighten it. Fill the pump with fluid.

14. With the front wheels still off the ground, as truck is still on jackstands, turn the steering wheel from stop to stop to bleed all the air out of the system check the fluid level often and top up as required. It helps to have the truck running :)

15. Replace the inner fender, if you had one to take off :), and replace the drivers wheel. Once again turn the wheel from stop to stop to ensure nothing is rubbing. Reinstall your rad fan shroud if you had one to remove.

16. Lower the truck to the ground and enjoy the "new steering feeling".

I hope these "instructions" are fairly clear. I am sure you will understand as you are doing the conversion what I mean. You will probably even see a better way to complete it. Good luck, email me any questions you might have Sparky@*spamremove*mail.island.net

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